Difference between revisions of "Platypus" - New World Encyclopedia

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| range_map_caption = Platypus range (indicated by darker shading)<ref name="APC">Australian Platypus Conservancy, [http://www.platypus.asn.au/ "Platypus facts file,"] ''Australian Platypus Conservancy''. Retrieved September 25, 2008.</ref>
 
| range_map_caption = Platypus range (indicated by darker shading)<ref name="APC">Australian Platypus Conservancy, [http://www.platypus.asn.au/ "Platypus facts file,"] ''Australian Platypus Conservancy''. Retrieved September 25, 2008.</ref>
 
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'''Platypus''' is the common name for a semi-[[Aquatic animal|aquatic]], [[egg (biology)|egg]]-laying [[mammal]], '''''Ornithorhynchus anatinus''''', [[Endemic (ecology)|endemic]] to eastern [[Australia]], including [[Tasmania]], and uniquely characterized by a snout like a [[duck]]'s bill, a broad and flat [[beaver]]-like tail, and webbed feet like an [[otter]]. It is one of only five extant species of [[monotreme]]s (order [[Monotremata]]), the only mammals that lay eggs instead of giving birth to live young. Also known as the '''duck-billed platypus''' and the '''duckbill''', it is the sole living representative of its [[Family (biology)|family]] ([[Ornithorhynchidae]]) and [[genus]] (''Ornithorhynchus''), though a number of [[Monotreme#Fossil monotremes|related species]] have been found in the fossil record. The platypus is one of the few venomous mammals; the male platypus has a spur on the hind foot that delivers a venom capable of causing severe pain to humans.  
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'''Platypus''' is the common name for a semi-[[Aquatic animal|aquatic]], [[egg (biology)|egg]]-laying [[mammal]], '''''Ornithorhynchus anatinus''''', [[Endemic (ecology)|endemic]] to eastern [[Australia]], including [[Tasmania]], and uniquely characterized by a snout like a [[duck]]'s bill, a broad and flat [[beaver]]-like tail, and webbed feet like an [[otter]]. It is one of only five extant species of [[monotreme]]s (order [[Monotremata]]), the only mammals that lay eggs instead of giving birth to live young. Also known as the '''duck-billed platypus''' and the '''duckbill''', it is the sole living representative of its [[Family (biology)|family]] ([[Ornithorhynchidae]]) and [[genus]] ''(Ornithorhynchus),'' though a number of [[Monotreme#Fossil monotremes|related species]] have been found in the fossil record. The platypus is one of the few venomous mammals; the male platypus has a spur on the hind foot that delivers a [[venom]] capable of causing severe pain to humans.  
  
The bizarre appearance of this egg-laying, venomous, duck-billed, beaver-tailed, otter-footed mammal baffled European naturalists when they first encountered descriptions and a pelt, with some considering it an elaborate hoax. The unique features of the platypus make it an important subject in the study of evolutionary biology and a recognizable and iconic symbol of [[Australia]].
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The bizarre appearance of this egg-laying, venomous, duck-billed, beaver-tailed, otter-footed mammal baffled European naturalists when they first encountered descriptions and a pelt, with some considering it an elaborate hoax. Despite a limited distribution, it is one of the more well-known animals worldwide given its unique features, and it is a recognizable and iconic symbol of Australia. Its singular characteristics also make the platypus an important subject in the study of evolutionary biology. Ecologically, it has an important role in [[food chain]]s, feeding on freshwater [[shrimp]], [[crayfish]], [[annelid]]s, and insect larvae, and being consumed by [[snake]]s, birds of prey, crocodiles, and other predators.
 
 
Until the early 20th century it was hunted for its fur, but it is now protected throughout its range. Although captive breeding programs have had only limited success and the Platypus is vulnerable to the effects of pollution, it is not under any immediate threat.
 
  
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Until the early twentieth century, the platypus was hunted for its [[fur]], but it is now protected throughout its range. Although captive breeding programs have had only limited success and the Platypus is vulnerable to the effects of [[pollution]], it is not under any immediate threat.
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{{toc}}
 
The plural usually is formed as either platypuses or platypus, with either correct, although platypi also appears on occasion.
 
The plural usually is formed as either platypuses or platypus, with either correct, although platypi also appears on occasion.
  
 
==Overview and description==
 
==Overview and description==
[[Image:platypus-sketch.jpg|left|200px|thumb|A color print of platypuses from 1863]]<!--[[Image:Platypus.jpg|left|thumb|250px|A platypus in [[Sydney Aquarium]] in 2004]]—>
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[[Image:platypus-sketch.jpg|right|250px|thumb|A color print of platypuses from 1863]]
The platypus and four species of echidnas ("spiny anteaters") comprise the only extant species of monotremes, the egg-laying mammals of the order ''Monotremata'', the only order in subclass Monotremata (or Prototheria). Monotremes are one of three subdivisions of mammals, the other two being the [[placental]]s (Placentalia or Eutheria) and the [[marsupial]]s (Marsupialia or Metatheria), both of which give birth to live young. The key [[physiology|physiological]] difference between monotremes and other mammals is that in monotremes the [[urinary system|urinary]], defecatory, and [[reproductive system]]s all open into a single duct, the cloaca. Other mammal females have separate openings for reproduction, urination, and defecation. Monotremes are placed in two families, with the platypus belonging to Ornithorhynchidae and the four species of echidnas in the Tachyglossidae family. Echidnas also are found in Australia, as well as [[New Guinea]].
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The platypus and four species of echidnas ("spiny anteaters") comprise the only extant species of monotremes, the egg-laying mammals of the order ''Monotremata,'' the only order in subclass Monotremata (or Prototheria). Monotremes are one of three subdivisions of mammals, the other two being the [[placental]]s (Placentalia or Eutheria) and the [[marsupial]]s (Marsupialia or Metatheria), both of which give birth to live young. The key [[physiology|physiological]] difference between monotremes and other mammals is that in monotremes the [[urinary system|urinary]], defecatory, and [[reproductive system]]s all open into a single duct, the cloaca. Other mammal females have separate openings for reproduction, urination, and defecation. Monotremes are placed in two families, with the platypus belonging to Ornithorhynchidae and the four species of echidnas in the Tachyglossidae family. Echidnas also are found in [[Australia]], as well as [[New Guinea]].
  
The squat body and the broad, flat tail of the platypus are covered with dense brown [[fur]] that traps a layer of insulating air to keep the animal warm.<ref name="APC" /><ref name="ABRS" /> The platypus uses its tail for storage of fat reserves (an adaptation also found in animals such as the [[Tasmanian devil]]<ref name="Guiler">E. R. Guiler, E.R., "Tasmanian devil," pages 27 to 28 in R. Strahan, ed., ''The Australian Museum Complete Book of Australian Mammals'' (Angus & Robertson 1983). ISBN 0207144540.</ref> and [[fat-tailed sheep]]). It has webbed feet and a large, rubbery snout; these are features that appear closer to those of a duck than to those of any known mammal. Unlike a [[bird]]'s [[beak]] (in which the upper and lower parts separate to reveal the mouth), the snout of the platypus is a sensory organ with the mouth on the underside. The nostrils are located on the dorsal surface of the snout, while the eyes and ears are located in a groove set just back from it; this groove is closed when swimming.<ref name="ABRS" /> The webbing is more significant on the front feet and is folded back when walking on land.<ref name="ABRS" />   
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The squat body and the broad, flat tail of the platypus are covered with dense brown [[fur]] that traps a layer of insulating air to keep the animal warm.<ref name="APC" /><ref name="ABRS" /> The platypus uses its tail for storage of fat reserves (an adaptation also found in animals such as the [[Tasmanian devil]]<ref name="Guiler">E. R. Guiler, "Tasmanian devil," pages 27 to 28 in R. Strahan, (ed.), ''The Australian Museum Complete Book of Australian Mammals.'' (Angus & Robertson 1983). ISBN 0207144540.</ref> and [[fat-tailed sheep]]). It has webbed feet and a large, rubbery snout; these are features that appear closer to those of a duck than to those of any known mammal. Unlike a [[bird]]'s [[beak]] (in which the upper and lower parts separate to reveal the mouth), the snout of the platypus is a sensory organ with the mouth on the underside. The nostrils are located on the dorsal surface of the snout, while the eyes and ears are located in a groove set just back from it; this groove is closed when swimming.<ref name="ABRS" /> The webbing is more significant on the front feet and is folded back when walking on land.<ref name="ABRS" />   
  
 
Weight varies considerably from 0.7 to 2.4 kilograms (1.5 to 5.3 pounds), with males being larger than females: males average 50 centimeters (20 inches) in total length while females average 43 centimeters (17 inches)<ref name="ABRS" /> There is substantial variation in average size from one region to another, and this pattern does not seem to follow any particular climatic rule and may be due to other environmental factors, such as predation and human encroachment.<ref name="Workshop">S. Munks, and S. Nicol, [http://www.medicine.utas.edu.au/research/mono/Taspaper.html "Current research on the platypus, ''Ornithorhynchus anatinus'' in Tasmania: Abstracts from the 1999 'Tasmanian Platypus WORKSHOP',"] ''University of Tasmania'' (1999). Retrieved September 25, 2008. </ref>
 
Weight varies considerably from 0.7 to 2.4 kilograms (1.5 to 5.3 pounds), with males being larger than females: males average 50 centimeters (20 inches) in total length while females average 43 centimeters (17 inches)<ref name="ABRS" /> There is substantial variation in average size from one region to another, and this pattern does not seem to follow any particular climatic rule and may be due to other environmental factors, such as predation and human encroachment.<ref name="Workshop">S. Munks, and S. Nicol, [http://www.medicine.utas.edu.au/research/mono/Taspaper.html "Current research on the platypus, ''Ornithorhynchus anatinus'' in Tasmania: Abstracts from the 1999 'Tasmanian Platypus WORKSHOP',"] ''University of Tasmania'' (1999). Retrieved September 25, 2008. </ref>
  
The Platypus has an average [[Core temperature|body temperature]] of about of about 32°C (90°F), rather than the 37°C (99°F) typical of [[placentalia|placental mammals]].<ref name="DC">Department of Biology, Davidson College, ["http://www.bio.davidson.edu/courses/anphys/1999/White/thermal.htm "Thermal biology of the platypus,"] ''Davidson College'' (1999). Retrieved September 25, 2008.</ref> Research suggests this has been a gradual adaptation to harsh environmental conditions on the part of the small number of surviving monotreme species rather than a historical characteristic of monotremes.<ref name="temp">J. M. Watson, and J. A. M. Graves, [http://www.publish.csiro.au/?paper=ZO9880573 "Monotreme cell-cycles and the evolution of homeothermy,"] ''Australian Journal of Zoology'' 36(1988)(issue 5): 573–584. Retrieved September 25, 2008.</ref><ref name="temp2">T. J. Dawson, T. R. Grant, and D. Fanning, [http://www.publish.csiro.au/?paper=ZO9790511 "Standard metabolism of monotremes and the evolution of homeothermy,"] ''Australian Journal of Zoology'' 27(1979)(issue 4): 511–515. Retrieved September 25, 2008. </ref>
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The platypus has an average [[Core temperature|body temperature]] of about of about 32°C (90°F), rather than the 37°C (99°F) typical of [[placentalia|placental mammals]].<ref name="DC">Department of Biology, Davidson College, ["http://www.bio.davidson.edu/courses/anphys/1999/White/thermal.htm "Thermal biology of the platypus,"] ''Davidson College'' (1999). Retrieved September 25, 2008.</ref> Research suggests this has been a gradual adaptation to harsh environmental conditions on the part of the small number of surviving monotreme species rather than a historical characteristic of monotremes.<ref name="temp">J. M. Watson, and J. A. M. Graves, [http://www.publish.csiro.au/?paper=ZO9880573 "Monotreme cell-cycles and the evolution of homeothermy,"] ''Australian Journal of Zoology'' 36(1988)(issue 5): 573–584. Retrieved September 25, 2008.</ref><ref name="temp2">T. J. Dawson, T. R. Grant, and D. Fanning, [http://www.publish.csiro.au/?paper=ZO9790511 "Standard metabolism of monotremes and the evolution of homeothermy,"] ''Australian Journal of Zoology'' 27 (4)(1979): 511–515. Retrieved September 25, 2008. </ref>
  
The modern Platypus young have three-cusped [[Molar (tooth)|molars]] which they lose before or just after leaving the breeding burrow;<ref name="MS">R. Pascual, F. J. Goin, L. Balarino, and D. E. Udrizar Sauthier, "New data on the Paleocene monotreme ''Monotrematum sudamericanum'', and the convergent evolution of triangulate molars," ''Acta Palaeontologica Polonica'' 47(2002)(issue 3): 487–492.</ref><ref name="geowords">{{cite web|url=http://geowords.com/histbooknetscape/f01.htm|title=Living mammals are placentals (eutheria), marsupials, and monotremes|publisher=Geowords|author=Hugh Race| accessdate = 2006-09-19}}</ref> adults have heavily keratinised pads in their place.<ref name="ABRS" /> The Platypus [[jaw]] is constructed differently from that of other mammals, and the jaw-opening muscle is different.<ref name="ABRS" /> As in all true mammals, the tiny bones that conduct sound in the [[middle ear]] are fully incorporated into the skull, rather than lying in the jaw as in [[cynodont]]s and other pre-mammalian [[synapsid]]s. However, the external opening of the ear still lies at the base of the jaw.<ref name="ABRS" /> The Platypus has extra bones in the shoulder girdle, including an [[interclavicle]], which is not found in other mammals.<ref name="ABRS" /> It has a [[Reptile|reptilian]] gait, with legs that are on the sides of the body, rather than underneath.<ref name="ABRS" />
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The modern platypus young have three-cusped [[Molar (tooth)|molars]] which they lose before or just after leaving the breeding burrow;<ref name="MS">R. Pascual, F. J. Goin, L. Balarino, and D. E. Udrizar Sauthier, "New data on the Paleocene monotreme ''Monotrematum sudamericanum'', and the convergent evolution of triangulate molars," ''Acta Palaeontologica Polonica'' 47(3) (2002): 487–492.</ref><ref name="geowords">H. Rance, "Living mammals are placentals (eutheria), marsupials, and monotremes," pages 304-306 in ''The Age of Mammals''. </ref> adults have heavily keratinized pads in their place.<ref name="ABRS" /> The platypus [[jaw]] is constructed differently from that of other mammals, and the jaw-opening muscle is different.<ref name="ABRS" /> As in all true mammals, the tiny bones that conduct sound in the [[middle ear]] are fully incorporated into the skull, rather than lying in the jaw as in [[cynodont]]s and other pre-mammalian [[synapsid]]s. However, the external opening of the ear still lies at the base of the jaw.<ref name="ABRS" /> The platypus has extra bones in the shoulder girdle, including an [[interclavicle]], which is not found in other mammals.<ref name="ABRS" /> It has a [[Reptile|reptilian]] gait, with legs that are on the sides of the body, rather than underneath.<ref name="ABRS" />
  
 
=== Venom ===
 
=== Venom ===
 
{{main|Platypus venom}}
 
 
[[Image:Platypus spur.JPG|right|thumb|The calcaneus spur found on the male's hind limb is used to deliver venom.]]
 
[[Image:Platypus spur.JPG|right|thumb|The calcaneus spur found on the male's hind limb is used to deliver venom.]]
  
The male Platypus has ankle spurs which produce a cocktail of venom,<ref>[http://www.australianfauna.com/platypus.php Australian Fauna]</ref><ref>[http://www.usyd.edu.au/news/84.html?newsstoryid=2267 The University of Sydney] </ref><ref>[http://rainforest-australia.com/platypus_poison.htm Rainforest Australia]</ref>
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The male platypus has ankle spurs that produce a cocktail of venom,<ref>Australian Fauna, [http://www.australianfauna.com/platypus.php "Platypus ''(Ornithorhynchus anatinus)'',"] ''Australianfauna.com'' (2006). Retrieved September 25, 2008.</ref><ref>University of Sydney, [http://www.usyd.edu.au/news/84.html?newsstoryid=2267 "Platypus venom linked to pain relief,"] ''University of Sydney'' (2008). Retrieved September 25, 2008.</ref><ref>Rainforest Australia, "Platypus poison,". ''Rainforest Australia''. </ref> composed largely of [[defensin]]-like [[protein]]s (DLPs); the venom is unique to the platypus.<ref name="PS">V. B. Gerritsen, [http://www.expasy.org/spotlight/back_issues/sptlt029.shtml "Platypus poison,"] ''Protein Spotlight'' 29(2002). Retrieved September 25, 2008.</ref> Although powerful enough to kill smaller animals,<ref name="PS" /> the venom is not lethal to humans, but is so excruciating that the victim may be incapacitated. [[Edema|Oedema]] rapidly develops around the wound and gradually spreads throughout the affected limb. Information obtained from [[Case study|case histories]] and anecdotal evidence indicates that the pain develops into a long-lasting [[hyperalgesia]] that persists for days or even months.<ref name="JN">G. M. de Plater, P. J. Milburn, and R. L. Martin, [http://jn.physiology.org/cgi/reprint/85/3/1340 "Venom from the platypus, ''Ornithorhynchus anatinus'', induces a calcium-dependent current in cultured dorsal root ganglion cells,"] ''Journal of Neurophysiology'' 85(2001)(issue 3): 1340–1345. Retrieved September 25, 2008.</ref><ref name="venom">B. G. Frey, "The venom of the platypus ''(Ornithorhynchus anatinus)'', ''Kingsnake.com''. </ref> Venom is produced in the crural glands of the male, which are [[kidney]]-shaped [[alveolar gland]]s connected by a thin-walled duct to a [[calcaneus]] spur on each hind limb. The female platypus, in common with [[echidna]]s, has rudimentary spur buds that do not develop (dropping off before the end of their first year) and lack functional crural glands.<ref name="ABRS" />
composed largely of [[defensin]]-like [[protein]]s (DLPs), which is unique to the Platypus.<ref name="PS">{{cite journal| last = Gerritsen| first = Vivienne Baillie | title = Platypus poison| journal = Protein Spotlight| issue = 29| date = 2002-12| url = http://www.expasy.org/spotlight/back_issues/sptlt029.shtml| accessdate = 14 September|accessyear=2006 }}</ref> Although powerful enough to kill smaller animals,<ref name="PS" /> the venom is not lethal to humans, but is so excruciating that the victim may be incapacitated. [[Edema|Oedema]] rapidly develops around the wound and gradually spreads throughout the affected limb. Information obtained from [[Case study|case histories]] and anecdotal evidence indicates that the pain develops into a long-lasting [[hyperalgesia]] that persists for days or even months.<ref name="JN">{{cite journal|journal= Journal of Neurophysiology|title=Venom From the Platypus, ''Ornithorhynchus anatinus'', Induces a Calcium-Dependent Current in Cultured Dorsal Root Ganglion Cells|author=G. M. de Plater, P. J. Milburn and R. L. Martin|volume=85|issue=3|pages=1340–1345|date=2001-3|publisher=American Physiological Society|url=http://jn.physiology.org/cgi/reprint/85/3/1340}}</ref><ref name="venom">{{cite web|url=http://www.kingsnake.com/toxinology/old/mammals/platypus.html|title=The venom of the platypus (Ornithorhynchus anatinus)| accessdate = 2006-09-13}}</ref> Venom is produced in the [[wiktionary:crural|crural]] glands of the male, which are kidney-shaped [[alveolar gland]]s connected by a thin-walled duct to a [[calcaneus]] spur on each hind limb. The female Platypus, in common with echidnas, has rudimentary spur buds which do not develop (dropping off before the end of their first year) and lack functional crural glands.<ref name="ABRS" />
 
  
The venom appears to have a different function from those produced by non-mammalian species: its effects are not life-threatening but nevertheless powerful enough to seriously impair the victim. Since only males produce venom and production rises during the breeding season, it is theorised that it is used as an offensive weapon to assert dominance during this period.<ref name="PS" />
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The venom appears to have a different function from those produced by non-mammalian species: Its effects are not life-threatening but nevertheless powerful enough to seriously impair the victim. Since only males produce venom and production rises during the breeding season, it is theorized that it is used as an offensive weapon to assert dominance during this period.<ref name="PS" />
  
 
=== Electrolocation ===
 
=== Electrolocation ===
  
Monotremes (see also [[echidna]] for the other species) are the only mammals known to have a sense of [[electroreception]]: they locate their prey in part by detecting electric fields generated by muscular contractions. The Platypus' electroreception is the most sensitive of any monotreme.<ref name="Electro1">{{cite journal| last = Pettigrew| first = John D.| title = Electroreception in Monotremes| journal = The Journal of Experimental Biology|pages=1447–1454| issue = 202| date = 1999| url = http://jeb.biologists.org/cgi/reprint/202/10/1447.pdf| accessdate = 19 September|accessyear=2006 |format=PDF}}</ref>
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Monotremes are the only mammals known to have a sense of [[electroreception]]: They locate their prey in part by detecting electric fields generated by muscular contractions. The platypus' electroreception is the most sensitive of any monotreme.<ref name="Electro1">J. D. Pettigrew, [http://jeb.biologists.org/cgi/reprint/202/10/1447.pdf "Electroreception in monotremes,"] ''The Journal of Experimental Biology'' 202(1999): 1447–1454. Retrieved September 25, 2008. </ref>
  
The [[electroreceptor]]s are located in rostro-caudal rows in the skin of the bill, while [[mechanoreceptor]]s (which detect touch) are uniformly distributed across the bill. The electrosensory area of the [[cerebral cortex]] is contained within the tactile [[somatosensory]] area, and some cortical cells receive input from both electroreceptors and mechanoreceptors, suggesting a close association between the tactile and electric senses. Both electroreceptors and mechanoreceptors in the bill dominate the [[somatotopic map]] of the platypus brain, in the same way human hands dominate the [[Cortical homunculus|Penfield homunculus map]].<ref name="sensory_platypus">{{cite journal
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The [[electroreceptor]]s are located in rostro-caudal rows in the skin of the bill, while [[mechanoreceptor]]s (which detect touch) are uniformly distributed across the bill. The electrosensory area of the [[cerebral cortex]] is contained within the tactile [[somatosensory]] area, and some cortical cells receive input from both electroreceptors and mechanoreceptors, suggesting a close association between the tactile and electric senses. Both electroreceptors and mechanoreceptors in the bill dominate the [[somatotopic map]] of the platypus brain, in the same way human hands dominate the [[Cortical homunculus|Penfield homunculus map]].<ref name="sensory_platypus">J. D. Pettigrew, P. R. Manger, and S. L. Fine, [http://www.pubmedcentral.nih.gov/picrender.fcgi?artid=1692312&blobtype=pdf "The sensory world of the platypus,"] ''Philosophical Transactions of the Royal Society of London'' 353(1998): 1199–1210. Retrieved September 25, 2008.</ref><ref name="Ancestors_Tale">R. Dawkins, ''The Ancestor's Tale, A Pilgrimage to the Dawn of Life'' (Boston: Houghton Mifflin Company, 2004). ISBN 0618005838.</ref>
| last = Pettigrew
 
| first = John D.
 
| coauthors = P R Manger, and S L Fine
 
| title = The sensory world of the platypus
 
| journal = Philosophical Transactions of the Royal Society of London
 
| pages = 1199–1210
 
| issue = 353
 
| date = 1998
 
| url = http://www.pubmedcentral.nih.gov/picrender.fcgi?artid=1692312&blobtype=pdf
 
| accessdate = 8 August
 
| accessyear = 2007
 
}}</ref><ref name="Ancestors_Tale">{{cite book
 
| first = Richard
 
| last = Dawkins
 
| authorlink = Richard Dawkins
 
| title = [[The Ancestor's Tale|The Ancestor's Tale, A Pilgrimage to the Dawn of Life]]
 
| chapter = The Duckbill's Tale
 
| publisher = Houghton Mifflin Company
 
| location = Boston
 
| year = 2004
 
| id = ISBN 0-618-00583-8 }}</ref>
 
  
The Platypus can determine the direction of an electric source, perhaps by comparing differences in [[signal strength]] across the sheet of electroreceptors. This would explain the animal's characteristic side-to-side motion of its head while hunting. The cortical convergence of electrosensory and tactile inputs suggests a mechanism for determining the distance of prey items which, when they move, emit both electrical signals and mechanical pressure pulses, which would also allow for computation of distance from the difference in time of arrival of the two signals.<ref name="Electro1" />
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The platypus can determine the direction of an electric source, perhaps by comparing differences in [[signal strength]] across the sheet of electroreceptors. This would explain the animal's characteristic side-to-side motion of its head while hunting. The cortical convergence of electrosensory and tactile inputs suggests a mechanism for determining the distance of prey items which, when they move, emit both electrical signals and mechanical pressure pulses, which would also allow for computation of distance from the difference in time of arrival of the two signals.<ref name="Electro1" />
  
The Platypus feeds by digging in the bottom of streams with its bill. The electroreceptors could be used to distinguish animate and inanimate objects in this situation (in which the mechanoreceptors would be continuously stimulated).<ref name="Electro1" /> When disturbed, its prey would generate tiny electrical currents in their muscular contractions which the sensitive electroreceptors of the Platypus could detect. Experiments have shown that the Platypus will even react to an "artificial shrimp" if a small electrical current is passed through it.<ref name=Manning>{{cite book | author = Manning, A & Dawkins, M.S. |title = An Introduction to Animal Behaviour Fifth Edition | publisher = Cambridge University Press | year = 1998}}</ref>
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The platypus feeds by digging in the bottom of streams with its bill. The electroreceptors could be used to distinguish animate and inanimate objects in this situation (in which the mechanoreceptors would be continuously stimulated).<ref name="Electro1" /> When disturbed, its prey would generate tiny electrical currents in their muscular contractions, which the sensitive electroreceptors of the platypus could detect. Experiments have shown that the platypus will even react to an "artificial shrimp" if a small electrical current is passed through it.<ref name=Manning>A. Manning, and M. S. Dawkins, ''An Introduction to Animal Behavior'', 5th edition. (Cambridge University Press, 1998). ISBN 0521570247</ref>
  
== Ecology and behaviour ==
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== Ecology and behavior ==
  
[[Image:Platipus-on-the-surface.jpg|thumb|The platypus is very difficult to spot even on the surface of a river.]]
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[[Image:Platipus-on-the-surface.jpg|thumb|300px|The platypus is very difficult to spot even on the surface of a river.]]
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The platypus is semi-aquatic, inhabiting small streams and rivers over an extensive range from the cold highlands of [[Tasmania]] and the [[Australian Alps]] to the [[tropical rainforest]]s of coastal [[Queensland]] as far north as the base of the [[Cape York Peninsula]].<ref name="DPIW">Department of Primary Industries and Water (DPIW), Tasmania, [http://www.dpiw.tas.gov.au/inter.nsf/WebPages/BHAN-53573T?open "Platypus,"] ''Department of Primary Industries and Water, Tasmania''. Retrieved September 25, 2008.</ref> Inland, its distribution is not well known: it is extinct in [[South Australia]] (barring an introduced population on [[Kangaroo Island]]) and is no longer found in the main part of the [[Murray-Darling Basin]], possibly due to the declining [[water quality]] brought about by extensive land clearing and [[irrigation]] schemes.<ref name="CSIRO">A. Scott and T. Grant, "Impacts of water management in the Murray-Darling Basin on the platypus ''(Ornithorhynchus anatinus)'' and the water rat ''(Hydromus chrysogaster)''," ''CSIRO Australia Technical Report 23/97'' (1997). </ref> Along the coastal river systems, its distribution is unpredictable; it appears to be absent from some relatively healthy rivers, and yet maintains a presence in others that are quite degraded (the lower [[Maribyrnong River|Maribyrnong]], for example).<ref name="APC2">Australian Platypus Conservancy, [http://www.platypus.asn.au/platypus_in_country_areas.html "Platypus in country areas,"] ''Australian Platypus Conservancy''. Retrieved September 25, 2008.</ref>
  
The Platypus is semi-aquatic, inhabiting small streams and rivers over an extensive range from the cold highlands of [[Tasmania]] and the [[Australian Alps]] to the [[tropical rainforest]]s of coastal [[Queensland]] as far north as the base of the [[Cape York Peninsula]].<ref name="DPIW">{{cite web|url=http://www.dpiw.tas.gov.au/inter.nsf/WebPages/BHAN-53573T?open|title=Platypus|publisher = Department of Primary Industries and Water, Tasmania|date=2006-08-31| accessdate = 2006-10-12}}</ref> Inland, its distribution is not well known: it is extinct in [[South Australia]] (barring an introduced population on [[Kangaroo Island]])<ref name="RKI">{{cite web|url=http://web.archive.org/web/www.ees.adelaide.edu.au/research/fbp/ki_res/|title=Research on Kangaroo Island|publisher=University of Adelaide|date=2006-07-04| accessdate = 2006-10-23}}</ref> and is no longer found in the main part of the [[Murray-Darling Basin]], possibly due to the declining [[water quality]] brought about by extensive land clearing and [[irrigation]] schemes.<ref name="CSIRO">{{cite web|
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Its habitat bridges [[river]]s and the [[riparian zone]] for both a food supply of prey species and banks where it can dig resting and nesting burrows.<ref name="HCP" /> It may have a range of up to 7 kilometers (4.3 miles), with male's home ranges overlapping with those of 3 or 4 females.<ref name="AJZ4">J. L. Gardner and M. Serena, [http://www.publish.csiro.au/?paper=ZO9950091 "Spatial-organization and movement patterns of adult male platypus, ''Ornithorhynchus anatinus'' (Monotremata, Ornithorhynchidae),"] ''Australian Journal of Zoology'' 43(1995)(issue 1): 91–103. Retrieved September 26, 2008.</ref>
url=http://www.clw.csiro.au/publications/technical97/tr23-97.pdf|
 
title=Impacts of water management in the Murray-Darling Basin on the platypus (''Ornithorhynchus anatinus'') and the water rat (''Hydromus chrysogaster'')|author=Anthony Scott and Tom Grant|publisher=CSIRO Australia|date=1997-11| accessdate = 2006-10-23|format=PDF}}</ref> Along the coastal river systems, its distribution is unpredictable; it appears to be absent from some relatively healthy rivers, and yet maintains a presence in others that are quite degraded (the lower [[Maribyrnong River|Maribyrnong]], for example).<ref name="APC2">{{cite web|url=http://www.platypus.asn.au/platypus_in_country_areas.html|title=Platypus in Country Areas|publisher=Australian Platypus Conservancy| accessdate = 2006-10-23}}</ref>
 
  
Platypuses have been heard to emit a low growl when disturbed and a range of other vocalizations have been reported in captive specimens.<ref name="APC" />
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The platypus is generally regarded as [[nocturnal]] and [[crepuscular]], but individuals are also active during the day, particularly when the sky is overcast.<ref name="HCP">T. G. Grant, and P. D. Temple-Smith, [http://journals.royalsociety.org/content/vlw4fua59muvy46x/ "Field biology of the platypus ''(Ornithorhynchus Anatinus)'': Historical and current perspectives,"] ''Philosophical Transactions: Biological Sciences'' 353(1998)(issue 1372): 1081–1091. Retrieved September 26, 2008.</ref>
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The platypus is an excellent swimmer and spends much of its time in the water foraging for food. When swimming, it can be distinguished from other Australian mammals by the absence of visible ears.<ref name="parks">Parks and Wildlife Service, Tasmania, [http://www.parks.tas.gov.au/index.aspx?base=4789 "Platypus, ''Ornithorhynchus anatinus'',"] ''Parks and Wildlife Service, Tasmania''. Retrieved September 26, 2008.</ref> Uniquely among mammals, it propels itself when swimming by alternate rowing motion with the front two feet; although all four feet of the Platypus are webbed, the hind feet (which are held against the body) do not assist in propulsion, but are used for steering in combination with the tail.<ref name="Rowing">F. E. Fish, R. V. Baudinette, P. B. Frappell, and M. P. Sarre, [http://jeb.biologists.org/cgi/reprint/200/20/2647.pdf "Energetics of swimming by the platypus ''Ornithorhynchus Anatinus'': Metabolic effort associated with rowing,"] ''The Journal of Experimental Biology'' 200(1997)(issue 20): 2647–2652. Retrieved September 26, 2008.</ref> Dives normally last around 30 seconds, but can last longer although few exceed the estimated aerobic limit of 40 seconds. Ten to twenty seconds are commonly spent in recovery at the surface.<ref name="Bethge">P. Bethge, "Energetics and foraging behavior of the platypus," ''University of Tasmania'' (2002). </ref><ref>H. Kruuk,  "The diving behaviour of the platypus ''(Ornithorhynchus anatinus)'' in waters with different trophic status," ''The Journal of Applied Ecology'' 30(1993)(issue 4): 592–598.</ref> The species is [[Warm-blooded|endothermic]], maintaining its body temperature about 32°C (90°F), lower than most mammals, even while foraging for hours in water below 5°C (41°F).<ref name="ABRS" />
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The platypus is a [[carnivore]]. It feeds on [[annelid]] worms and [[Larva|insect larvae]], freshwater [[shrimp]]s, and [[yabbie]]s (freshwater crayfish) that it digs out of the riverbed with its snout or catches while swimming. It utilizes cheek-pouches to carry prey to the surface where they are eaten.<ref name="parks" /> The platypus needs to eat about twenty percent of its own weight each day. This requires the platypus to spend an average of 12 hours each day looking for food.<ref name="Bethge" /> When not in the water, the platypus retires to a short, straight resting burrow of oval cross-section, nearly always in the riverbank not far above water level, and often [[Camouflage|hidden]] under a protective tangle of roots.<ref name="parks" />
  
In captivity, Platypuses have survived to seventeen years of age and wild specimens have been recaptured at eleven years old. [[Mortality rate]]s for adults in the wild appear to be low.<ref name="ABRS" /> Natural predators include [[snake]]s, [[water rat]]s, [[goanna]]s, [[hawk]]s, [[owl]]s and [[eagle]]s. Low Platypus numbers in northern Australia are possibly due to predation by [[crocodile]]s.<ref name="EPA">{{cite web|url=http://www.epa.qld.gov.au/nature_conservation/wildlife/native_animals/platypus/| title=Platypus|publisher=Environmental Protection Agency/Queensland Parks and Wildlife Service|date=2006| accessdate = 2006-10-24}}</ref> The introduction of [[red fox]]es as a predator for [[rabbit]]s may have had some impact on its numbers on the mainland.<ref name="Workshop" /> The Platypus is generally regarded as [[nocturnal]] and [[crepuscular]], but individuals are also active during the day, particularly when the sky is overcast.<ref name="EC">{{cite web|url=http://www.biology.iastate.edu/intop/1Australia/04papers/CromerMonotrRepro.htm|title=Monotreme Reproductive Biology and Behavior|publisher=Iowa State University|author=Erica Cromer|date=2004-04-14| accessdate = 2006-10-23}}</ref><ref name="HCP">{{cite journal|journal=Philosophical Transactions: Biological Sciences|title=Field Biology of the Platypus (Ornithorhynchus Anatinus): Historical and Current Perspectives|publisher=The Royal Society|volume=353|issue=1372|author=T.G. Grant and P. D. Temple-Smith|date=1998-07-29|pages=1081–1091 | doi = 10.1098/rstb.1998.0267 <!--Retrieved from CrossRef by DOI bot—>}}</ref> Its habitat bridges [[rivers]] and the [[riparian zone]] for both a food supply of prey species and banks where it can dig resting and nesting burrows.<ref name="HCP" /> It may have a range of up to {{convert|7|km|mi|abbr=on}}, with male's home ranges overlapping with those of 3 or 4 females.<ref name="AJZ4">{{cite journal|journal=Australian Journal of Zoology|title=Spatial-Organization and Movement Patterns of Adult Male Platypus, Ornithorhynchus-Anatinus (Monotremata, Ornithorhynchidae)
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Natural predators include [[snake]]s, [[water rat]]s, [[goanna]]s, [[hawk]]s, [[owl]]s, and [[eagle]]s. Low platypus numbers in northern Australia are possibly due to predation by [[crocodile]]s.<ref name="EPA">Environmental Protection Agency, [http://www.epa.qld.gov.au/nature_conservation/wildlife/native_animals/platypus/ "Platypus ''(Ornithorhynchus anatinus)'',"] ''Environmental Protection Agency/Queensland Parks and Wildlife Service'' (2008). Retrieved September 25, 2008.</ref> The introduction of [[red fox]]es as a predator for [[rabbit]]s may have had some impact on its numbers on the mainland.<ref name="Workshop" />  
|publisher=CSIRO|volume=43|issue=1|author= J.L. Gardner and M. Serena |date=1995|pages=91–103 | doi = 10.1071/ZO9950091 <!--Retrieved from CrossRef by DOI bot—>
 
}}</ref>
 
  
The Platypus is an excellent swimmer and spends much of its time in the water foraging for food. When swimming it can be distinguished from other Australian mammals by the absence of visible ears.<ref name="parks">{{cite web|url=http://www.parks.tas.gov.au/factsheets/wildlife/Platypus.pdf|title =Platypus|publisher=Parks and Wildlife Service Tasmania|date=2003-12| accessdate = 2006-10-23|format=PDF}}</ref> Uniquely among mammals it propels itself when swimming by alternate rowing motion with the front two feet; although all four feet of the Platypus are webbed, the hind feet (which are held against the body) do not assist in propulsion, but are used for steering in combination with the tail.<ref name="Rowing">{{cite journal|journal=The Journal of Experimental Biology|volume=200|issue=20|pages=2647–2652|title=Energetics of Swimming by the Platypus ''Ornithorhynchus Anatinus'': Metabolic Effort Associated with Rowing|publisher=The Company of Biologists Limited|author=F.E. Fish, R.V. Baudinette, P.B. Frappell, and M.P. Sarre|date=1997-07-28|url=http://jeb.biologists.org/cgi/reprint/200/20/2647.pdf}}</ref> The species is [[Warm-blooded|endothermic]], maintaining its body temperature about {{convert|32|°C|°F}}, lower than most mammals, even while foraging for hours in water below {{convert|5|°C|°F}}.<ref name="ABRS" />
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Platypuses have been heard to emit a low growl when disturbed and a range of other vocalizations have been reported in captive specimens.<ref name="APC" />
  
Dives normally last around 30 seconds, but can last longer although few exceed the estimated aerobic limit of 40 seconds. 10 to 20 seconds are commonly spent in recovery at the surface.<ref name="Bethge">{{cite web|url=http://www.bethge.org/BethgePhD.pdf|title=Energetics and foraging behaviour of the platypus|publisher = University of Tasmania|author=Philip Bethge|date=2002-04| accessdate = 2006-10-23|format=PDF}}</ref><ref>{{cite journal|journal=The Journal of Applied Ecology|title=The Diving Behaviour of the Platypus (''Ornithorhynchus anatinus'') in Waters with Different Trophic Status|author=H. Kruuk|volume=30|issue=4|date=1993|pages=592–598 | doi = 10.2307/2404239 <!--Retrieved from CrossRef by DOI bot—>}}</ref> The Platypus is a [[carnivore]]: it feeds on [[annelid]] worms and [[Larva|insect larvae]], freshwater [[shrimp]]s, and [[yabbie]]s (freshwater crayfish) that it digs out of the riverbed with its snout or catches while swimming. It utilises cheek-pouches to carry prey to the surface where they are eaten.<ref name="parks" /> The Platypus needs to eat about 20% of its own weight each day. This requires the Platypus to spend an average of 12 hours each day looking for food.<ref name="Bethge" /> When not in the water, the Platypus retires to a short, straight resting burrow of oval cross-section, nearly always in the riverbank not far above water level, and often [[Camouflage|hidden]] under a protective tangle of roots.<ref name="parks" />
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=== Reproduction and life cycle===
  
=== Reproduction ===
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When the platypus was first discovered, scientists were divided over whether the female laid eggs. This was not confirmed until 1884 when [[W. H. Caldwell]] was sent to Australia where, after extensive searching assisted by a team of 150 Aborigines, he managed to discover a few eggs.<ref name="ABRS"/><ref name="PS"/> Mindful of the high cost of wiring England based on the cost per word, Caldwell famously, but tersely, wired [[London]], "Monotremes oviparous, ovum meroblastic." That is, monotremes lay eggs, and the eggs are similar to those of reptiles in that only part of the egg divides as it develops.
  
When the Platypus was first discovered, scientists were divided over whether the female laid eggs. This was not confirmed until 1884 when [[W. H. Caldwell]] was sent to Australia where, after extensive searching assisted by a team of 150 Aborigines, he managed to discover a few eggs.<ref name="ABRS"/><ref name="PS"/> Mindful of the high cost of wiring England based on the cost per word, Caldwell famously but tersely wired [[London]], "Monotremes oviparous, ovum meroblastic". That is, monotremes lay eggs, and the eggs are similar to those of reptiles in that only part of the egg divides as it develops. <!--Suggest moving this to article on Caldwell when written. A bit of historical footnote that better belongs to zoology or a person—>
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The species exhibits a single [[breeding season]]; mating occurs between June and October, with some local variation taking place in populations across the extent of its range.<ref name="EPA" /> Historical observation, mark and recapture studies, and preliminary investigations of population genetics indicate the possibility of resident and transient members of populations and suggest a [[Polygyny|polygynous]] mating system.<ref name="AJZ2">T. R. Grant, M. Griffiths, and R.M.C. Leckie, [http://www.publish.csiro.au/?paper=ZO9830881 "Aspects of lactation in the platypus, ''Ornithorhynchus anatinus'' (Monotremata), in waters of Eastern New South Wales,"] ''Australian Journal of Zoology'' 31(1983)(issue 6): 881–889. Retrieved September 26, 2008. </ref> Females are thought likely to become sexually mature in their second year, with breeding confirmed to still take place in animals over nine years old.<ref name="AJZ2"/>
  
The species exhibits a single [[breeding season]]; mating occurs between June and October, with some local variation taking place in populations across the extent of its range.<ref name="EPA" /> Historical observation, mark and recapture studies, and preliminary investigations of population genetics indicate the possibility of resident and transient members of populations and suggest a [[Polygyny|polygynous]] mating system.<ref name="AJZ2">{{cite journal|journal=Australian Journal of Zoology|title=Aspects of Lactation in the Platypus, ''Ornithorhynchus anatinus'' (Monotremata), in Waters of Eastern New South Wales|author=T.R. Grant, M. Griffiths and R.M.C. Leckie|volume=31|issue=6|pages=881–889|publisher=1983|doi=10.1071/ZO9830881|year=1983}}</ref> Females are thought likely to become sexually mature in their second year, with breeding confirmed to still take place in animals over nine years old.<ref name="AJZ2"/>
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Outside the mating season, the platypus lives in a simple ground burrow whose entrance is about 30 centimeters (12 inches) above the water level. After mating, the female constructs a deeper, more elaborate burrow up to 20 meters (66 feet) long and blocked with plugs at intervals (which may act as a safeguard against rising waters or predators, or as a method of regulating humidity and temperature).<ref name="ADW">A. B. Sorin and P. Myers, [http://animaldiversity.ummz.umich.edu/site/accounts/information/Ornithorhynchidae.html "Family Ornithorhynchidae (platypus),"] ''Animal Diversity Web'' (2001). Retrieved September 26, 2008.</ref>  
  
Outside the mating season, the Platypus lives in a simple ground burrow whose entrance is about {{convert|30|cm|in|abbr=on}} above the water level. After mating, the female constructs a deeper, more elaborate burrow up to {{convert|20|m|ft|abbr=on}} long and blocked with plugs at intervals (which may act as a safeguard against rising waters or predators, or as a method of regulating humidity and temperature).<ref name="ADW">{{cite web | url=http://animaldiversity.ummz.umich.edu/site/accounts/information/Ornithorhynchidae.html | title=Family Ornithorhynchidae (platypus) | author = Anna Bess Sorin and Phil Myers |publisher = University of Michigan Museum of Zoology|date=2001|accessdate=2006-10-24}}</ref> The male takes no part in caring for its young, and retreats to its yearlong burrow. The female softens the ground in the burrow with dead, folded, wet leaves and she fills the nest at the end of the tunnel with fallen leaves and reeds for bedding material. This material is dragged to the nest by tucking it underneath her curled tail.<ref name="APC" />
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The male takes no part in caring for its young, and retreats to its yearlong burrow. The female softens the ground in the burrow with dead, folded, wet leaves and she fills the nest at the end of the tunnel with fallen leaves and reeds for bedding material. This material is dragged to the nest by tucking it underneath her curled tail.<ref name="APC" />
  
The female Platypus has a pair of [[Ovary|ovaries]] but only the left one is functional.<ref name="EC" /> It lays one to three (usually two) small, leathery eggs (similar to those of reptiles), that are about {{convert|11|mm|in|abbr=on}} in diameter and slightly rounder than bird eggs.<ref name="BSED">{{cite journal|journal= Philosophical Transactions of the Royal Society B: Biological Sciences|title=Early development and embryology of the platypus|author=R. L. Hughes and L. S. Hall|volume=353|issue=1372|pages=1101–1114|publisher=The Royal Society|date=1998-07-29 | doi = 10.1098/rstb.1998.0269 <!--Retrieved from CrossRef by DOI bot—>}}</ref> The eggs develop ''[[in utero]]'' for about 28 days with only about 10 days of external [[Incubate|incubation]] (in contrast to a chicken egg, which spends about 1 day in tract and 21 days externally).<ref name="EC" /> After laying her eggs, the female curls around them. The incubation period is separated into three parts. In the first, the [[embryo]] has no functional organs and relies on the [[yolk sac]] for sustenance. The yolk is absorbed by the developing young.<ref>{{cite web|title=Ockhams Razor|work=The Puzzling Platypus|url=http://www.abc.net.au/rn/science/ockham/stories/s332655.htm|accessdate=2006-12-02}}</ref> During the second, the digits develop, and in the last, the [[egg tooth]] appears.<ref name="RS2">{{cite journal|journal=Philosophical Transactions: Biological Sciences|title =The Development of the External Features of the Platypus (''Ornithorhynchus Anatinus'')|author=Paul R. Manger, Leslie S. Hall, John D. Pettigrew|volume=353|issue=1372|pages=1115–1125|date=1998-07-29|publisher=The Royal Society|doi =10.1098/rstb.1998.0270}}</ref>
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The female platypus has a pair of [[Ovary|ovaries]] but only the left one is functional. It lays one to three (usually two) small, leathery eggs (similar to those of reptiles), that are about 11 millimeters (0.43 inches) in diameter and slightly rounder than bird eggs.<ref name="BSED">R. L. Hughes, and L. S. Hall, [http://journals.royalsociety.org/content/0qwmu5q0ut5jnp8p/ "Early development and embryology of the platypus,"] ''Philosophical Transactions of the Royal Society B: Biological Sciences'' 353(1998)(issue 1372): 1101–1114. Retrieved September 26, 2008. </ref> The eggs develop ''[[in utero]]'' for about 28 days with only about 10 days of external [[Incubate|incubation]] (in contrast to a chicken egg, which spends about 1 day in tract and 21 days externally). After laying her eggs, the female curls around them. The incubation period is separated into three parts. In the first, the [[embryo]] has no functional organs and relies on the [[yolk sac]] for sustenance. The yolk is absorbed by the developing young.<ref>A. Moyal, "The puzzling platypus," ''Ockhams Razor'' July 22, 2001. Radio National (Australia). </ref> During the second, the digits develop, and in the last, the [[egg tooth]] appears.<ref name="RS2">P. R. Manger, L. S. Hall, and J. D. Pettigrew, [http://journals.royalsociety.org/content/6lvgj7juvffateun/ "The development of the external features of the platypus ''(Ornithorhynchus anatinus)'',"] ''Philosophical Transactions: Biological Sciences'' 353(1998)(issue 1372): 1115–1125. Retrieved September 26, 2008. </ref>
  
The newly hatched young are vulnerable, blind, and hairless, and are fed by the mother's milk. Although possessing [[mammary gland]]s, the Platypus lacks teats. Instead, milk is released through pores in the skin. There are grooves on her abdomen that form pools of milk, allowing the young to lap it up.<ref name="APC" /><ref name="EPA" /> After they hatch, the offspring are suckled for three to four months. During incubation and weaning, the mother initially only leaves the burrow for short periods to forage. When doing so, she creates a number of thin soil plugs along the length of burrow possibly to protect the young from predators; pushing past these on her return forces water from her fur and allows the burrow to remain dry.<ref name="QM">{{cite web|url=http://www.qm.qld.gov.au/inquiry/leaflets/leaflet0010.pdf|title=Egg-laying mammals|publisher=Queensland Museum|date=2000-11| accessdate = 2006-10-24|format=PDF}}</ref> After about five weeks, the mother begins to spend more time away from her young and at around four months the young emerge from the burrow.<ref name="EPA" />
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The newly hatched young are vulnerable, blind, and hairless, and are fed by the mother's milk. Although possessing [[mammary gland]]s, the platypus lacks teats. Instead, milk is released through pores in the skin. There are grooves on the mother's abdomen that form pools of milk, allowing the young to lap it up.<ref name="APC" /><ref name="EPA" /> After they hatch, the offspring are suckled for three to four months. During incubation and weaning, the mother initially only leaves the burrow for short periods to forage. When doing so, she creates a number of thin soil plugs along the length of burrow, possibly to protect the young from predators; pushing past these on her return forces water from her fur and allows the burrow to remain dry.<ref name="QM">Queensland Museum, [http://www.qm.qld.gov.au/inquiry/factsheets/leaflet0010.pdf "Egg-laying mammals,"] ''Queensland Museum''. Retrieved September 26, 2008.</ref> After about five weeks, the mother begins to spend more time away from her young and at around four months the young emerge from the burrow.<ref name="EPA" />
  
== Taxonomy and etymology ==
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In captivity, platypuses have survived to 17 years of age and tagged wild specimens have been recaptured at 11 years old. [[Mortality rate]]s for adults in the wild appear to be low.<ref name="ABRS" />
  
When the Platypus was first discovered by Europeans in 1798, a [[Pelage|pelt]] and sketch were sent back to the [[Kingdom of Great Britain|United Kingdom]] by [[John Hunter (New South Wales)|Captain John Hunter]], the second Governor of [[New South Wales]].<ref name="Paradox">{{cite journal|journal=BioScience|title=The Paradoxical Platypus|author=Brian K. Hall|volume=49|issue=3|pages=211–218|publisher=American Institute of Biological Sciences|date=1999-03|doi=10.2307/1313511}}</ref> The British scientists were at first convinced that the attributes must have been a hoax.<ref name="APC" /> [[George Shaw]], who produced the first description of the animal in the ''Naturalist's Miscellany'' in 1799 stated that it was impossible not to entertain doubts as to its genuine nature, and [[Robert Knox]] believed it may have been produced by some Asian [[Taxidermy|taxidermist]].<ref name="hoax">{{cite web|url=http://www.museumofhoaxes.com/hoax/Hoaxipedia/Duckbilled_Platypus/|title= Duck-billed Platypus|publisher =Museum of hoaxes| accessdate = 2008-04-02}}</ref> It was thought that somebody had sewn a duck's beak onto the body of a beaver-like animal. Shaw even took a pair of scissors to the dried skin to check for stitches.<ref name="APC" />
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== History, taxonomy, and etymology ==
  
The common name, ''Platypus'', is Latin derived from the Greek words πλατύς ("platys", flat, broad) and πους ("pous", foot), meaning "flat foot".<ref> {{cite book|author=Liddell & Scott|year=1980|title=Greek-English Lexicon, Abridged Edition |publisher=Oxford University Press, Oxford, UK|id=ISBN 0-19-910207-4}}</ref> Shaw assigned it as a [[Linnaean taxonomy|Linnaean]] genus name when he initially described it, but the term was quickly discovered to already belong to the wood-boring [[ambrosia beetle]] (genus ''Platypus'').<ref name="ABRS">{{cite web|url=http://www.deh.gov.au/biodiversity/abrs/publications/fauna-of-australia/pubs/volume1b/16-ind.pdf#search=%22platypus%20pelt%201700%22|title=Fauna of Australia chap.16 vol.1b|author=J.R.Grant|publisher=Australian Biological Resources Study (ABRS)| accessdate = 2006-09-13}}</ref> It was independently described as ''Ornithorhynchus paradoxus'' by [[Johann Blumenbach]] in 1800 (from a specimen given to him by [[Sir Joseph Banks]])<ref name="NLA">{{cite web|url=http://www.nla.gov.au/pub/gateways/archive/52/p16a01.html|title=Platypus Paradoxes|publisher=National Library of Australia|date=2001–08| accessdate = 2006-09-14}}</ref> and following the rules of priority of nomenclature it was later officially recognised as ''Ornithorhynchus anatinus''.<ref name="ABRS"/>
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When the platypus was first discovered by Europeans in 1798, a [[Pelage|pelt]] and sketch were sent back to the [[Kingdom of Great Britain|United Kingdom]] by [[John Hunter (New South Wales)|Captain John Hunter]], the second Governor of [[New South Wales]].<ref name="Paradox">B. K. Hall, "The paradoxical platypus," ''BioScience'' 49 (3) (1999): 211–218.</ref> The British scientists were at first convinced that the attributes must have been a hoax.<ref name="APC" /> [[George Shaw]], who in 1799 produced the first description of the animal in the ''Naturalist's Miscellany,'' stated that it was impossible not to entertain doubts as to its genuine nature, and [[Robert Knox]] believed it may have been produced by some Asian [[Taxidermy|taxidermist]].<ref name="hoax">A. Boese, [http://www.museumofhoaxes.com/hoax/Hoaxipedia/Duckbilled_Platypus/ "Duck-billed platypus,"] ''Museum of Hoaxes''. Retrieved September 26, 2008.</ref> It was thought that somebody had sewn a duck's beak onto the body of a beaver-like animal. Shaw even took a pair of scissors to the dried skin to check for stitches.<ref name="APC" />
The scientific name ''Ornithorhynchus'' is derived from ''ορνιθόρυνχος'' ("ornithorhynkhos"), which literally means "bird snout" in [[Greek language|Greek]], and ''anatinus'', which means "duck-like" in [[Latin]].
 
  
There is no universally agreed upon plural of "platypus" in the English language. Scientists generally use "platypuses" or simply "platypus". Colloquially, "platypi" is also used for the plural, although this is [[pseudo-Latin]];<ref name="APC" /> the Greek plural would be "platypodes". Early [[United Kingdom|British]] [[settler]]s called it by many names, such as '''watermole''', '''duckbill''', and '''duckmole'''.<ref name="APC" /> The name "Platypus" is often prefixed with the adjective "duck-billed" to form '''Duck-billed Platypus''', despite there being only one species of Platypus.<ref name="UT">{{cite web|url=http://www.medicine.utas.edu.au/research/mono/Platpage.html|title=The Platypus|publisher=Department of Anatomy & Physiology, University of Tasmania|date=1997-07-03| accessdate = 2006-09-14}}</ref>
+
The common name, ''platypus,'' is Latin derived from the Greek words πλατύς or ''platys,'' meaning "flat" or "broad," and πους or ''pous,'' meaning "foot,"&mdash;in other words, ""flat foot."<ref>H. G. Liddell, and R. Scott. 1987. ''A Lexicon Abridged From Liddell and Scott's Greek-English Lexicon.'' (Oxford: Clarendon Press. ISBN 0199102074)</ref> Shaw assigned it as a [[Linnaean taxonomy|Linnaean]] genus name when he initially described it, but the term was quickly discovered to already belong to the wood-boring [[ambrosia beetle]] (genus ''Platypus'').<ref name="ABRS">J. R. Grant, [http://www.deh.gov.au/biodiversity/abrs/publications/fauna-of-australia/pubs/volume1b/16-ind.pdf#search=%22platypus%20pelt%201700%22 "Chapter 16, Ornithorhynchidae,"], in D. Walton, and B. J. Richardson, (eds.), ''Fauna of Australia. Volume 1B, Mammalia.'' (Canberra: Australian Govt. Pub. Service. 1989. ISBN 0644060565). Retrieved September 26, 2008.</ref> It was independently described as ''Ornithorhynchus paradoxus'' by [[Johann Blumenbach]] in 1800 (from a specimen given to him by [[Sir Joseph Banks]])<ref name="NLA">W. Horky, [http://www.nla.gov.au/pub/gateways/archive/52/p16a01.html "Platypus paradoxes,"] ''National Library of Australia'' 52 (2001). Retrieved September 26, 2008.</ref> and following the rules of priority of nomenclature, it was later officially recognize as ''Ornithorhynchus anatinus.''<ref name="ABRS"/>
 +
The scientific name ''Ornithorhynchus'' is derived from ''ορνιθόρυνχος'' ("ornithorhynkhos"), which literally means "bird snout" in [[Greek language|Greek]], and ''anatinus,'' which means "duck-like" in [[Latin]].
  
 +
There is no universally agreed upon plural of "platypus" in the English language. Scientists generally use "platypuses" or simply "platypus." Colloquially, "platypi" is also used for the plural, although this is [[pseudo-Latin]];<ref name="APC" /> the Greek plural would be "platypodes." Early [[United Kingdom|British]] [[settler]]s called it by many names, such as watermole, duckbill, and duckmole.<ref name="APC" /> The name "platypus" is often prefixed with the adjective "duck-billed" to form duck-billed platypus, despite there being only one species of platypus.<ref name="UT">P. Bethge, [http://www.medicine.utas.edu.au/research/mono/Platpage.html "Platypus,"] ''Department of Anatomy & Physiology, University of Tasmania'' (1997). Retrieved September 26, 2008.</ref>
  
 
== Evolution ==
 
== Evolution ==
  
 
[[Image:Platypus skeleton Pengo.jpg|left|thumb|200px|Platypus skeleton]]
 
[[Image:Platypus skeleton Pengo.jpg|left|thumb|200px|Platypus skeleton]]
 +
The platypus and other monotremes were very poorly understood and some of the nineteenth century myths that grew up around them&mdash;for example, that the monotremes were "inferior" or quasi-[[Reptile|reptilian]]&mdash;still endure.<ref name="Rodent">J. A. W. Kirsch, and G. C. Mayer, [http://journals.royalsociety.org/content/hdd4bxyt0dxx5ph1/ "The platypus is not a rodent: DNA hybridization, amniote phylogeny and the palimpsest theory,"] ''Philosophical Transactions of the Royal Society: Biological Sciences'' 353 (1372) (1998): 1221–1237. Retrieved September 26, 2008.</ref> In fact, modern monotremes are the survivors of an early branching of the mammal tree; a later branching is thought to have led to the [[marsupial]] and placental groups.<ref name="JME">
 +
M. Messer, A. S. Weiss, D. C. Shaw, and M. Westerman, [http://www.springerlink.com/content/j528128pt8546711/ "Evolution of the monotremes: Phylogenetic relationship to marsupials and eutherians, and estimation of divergence dates based on α-lactalbumin amino acid sequences,"] ''Journal of Mammalian Evolution'' 5(1)(1998): 95–105. Retrieved September 26, 2008.</ref><ref name="Rodent" /> Although in 1947, [[William King Gregory]] had theorized that placental mammals and marsupials may have diverged earlier and a subsequent branching divided the monotremes and marsupials, later research and fossil discoveries have suggested this is incorrect.<ref name="Rodent" /><ref name="JM">O. W. M. Rauhut, T. Martin, E. Ortiz-Jaureguizar, and P. Puerta, [http://www.nature.com/nature/journal/v416/n6877/extref/416165a-s1.doc "The first Jurassic mammal from South America,"] ''Nature''. Retrieved September 26, 2008.</ref>
  
The Platypus and other monotremes were very poorly understood and some of the 19th century myths that grew up around them — for example, that the monotremes were "inferior" or quasi-[[Reptile|reptilian]] — still endure.<ref name="Rodent">{{cite journal|journal=Philosophical Transactions: Biological Sciences|title=The Platypus is not a Rodent: DNA Hybridization, Amniote Phylogeny and the Palimpsest Theory|author=John A. W. Kirsch and Gregory C. Mayer|volume=353|issue=1372|pages=1221–1237|date=1998-07-29|doi=10.1098/rstb.1998.0278}}</ref> In fact, modern monotremes are the survivors of an early branching of the mammal tree; a later branching is thought to have led to the [[marsupial]] and placental groups.<ref name="JME">{{cite journal|journal=Journal of Mammalian Evolution|publisher=Springer Netherlands|title=Evolution of the Monotremes: Phylogenetic Relationship to Marsupials and Eutherians, and Estimation of Divergence Dates Based on α-Lactalbumin Amino Acid Sequences|author=M. Messer, A.S. Weiss, D.C. Shaw and M. Westerman|volume=5|issue=1|pages=95–105|date=1998-03 | doi = 10.1023/A:1020523120739 <!--Retrieved from CrossRef by DOI bot—>}}</ref><ref name="Rodent" /> Although in 1947, [[William King Gregory]] had theorised that placental mammals and marsupials may have diverged earlier and a subsequent branching divided the monotremes and marsupials, later research and fossil discoveries have suggested this is incorrect.<ref name="Rodent" /><ref name="JM">{{cite web|url=http://www.nature.com/nature/journal/v416/n6877/extref/416165a-s1.doc|title=The first Jurassic mammal from South America|author=O. W. M. Rauhut, T. Martin, E. Ortiz-Jaureguizar and P. Puerta|publisher=Nature| accessdate = 2006-10-24|date=2001-12-11|format=DOC}}</ref>
+
The oldest discovered fossil of the modern platypus dates back to about 100,000 years ago, during the [[Quaternary]] period. The extinct monotremes (''[[Teinolophos]]'' and ''[[Steropodon]]'') were closely related to the modern platypus.<ref name="JM" /> The fossilized ''Steropodon'' was discovered in [[New South Wales]] and is composed of an opalised lower jawbone with three molar teeth (whereas the adult contemporary platypus is toothless). The molar teeth were initially thought to be [[Tribosphenic molar|tribosphenic]], which would have supported a variation of Gregory's theory, but later research has suggested that, while they have three cusps, they evolved under a separate process.<ref name="MS" /> The fossil is thought to be about 110 million years old, which means that the platypus-like animal was alive during the [[Cretaceous]] period, making it the oldest mammal fossil found in Australia. ''[[Monotrematum sudamericanum]],'' another fossil relative of the Platypus, has been found in [[Argentina]], indicating that monotremes were present in the supercontinent of [[Gondwana]] when the continents of [[South America]] and Australia were joined via [[Antarctica]] (up to about 167 million years ago).<ref name="MS" /><ref name="patagonia">T. Folger, [http://www.findarticles.com/p/articles/mi_m1511/is_n1_v14/ai_13670058 "A platypus in Patagonia: Ancient life,"] ''Discover'' (1993). Retrieved September 26, 2008. </ref>
  
The oldest discovered fossil of the modern Platypus dates back to about 100,000 years ago, during the [[Quaternary]] period. The extinct monotremes (''[[Teinolophos]]'' and ''[[Steropodon]]'') were closely related to the modern Platypus.<ref name="JM" /> The fossilised ''Steropodon'' was discovered in [[New South Wales]] and is composed of an opalised lower jawbone with three molar teeth (whereas the adult contemporary Platypus is toothless). The molar teeth were initially thought to be [[Tribosphenic molar|tribosphenic]], which would have supported a variation of Gregory's theory, but later research has suggested that, while they have three cusps, they evolved under a separate process.<ref name="MS" /> The fossil is thought to be about 110 million years old, which means that the Platypus-like animal was alive during the [[Cretaceous]] period, making it the oldest mammal fossil found in Australia. ''[[Monotrematum sudamericanum]]'', another fossil relative of the Platypus, has been found in [[Argentina]], indicating that monotremes were present in the supercontinent of [[Gondwana]] when the continents of [[South America]] and Australia were joined via [[Antarctica]] (up to about 167 million years ago).<ref name="MS" /><ref name="patagonia">{{cite web|url=http://www.findarticles.com/p/articles/mi_m1511/is_n1_v14/ai_13670058|title=A platypus in Patagonia — Ancient life|author=Tim Folger|publisher=Discover|date=1993-01| accessdate = 2006-10-17}}</ref>
+
Because of the early divergence from the [[Theria|therian mammals]] and the low numbers of extant monotreme species, it is a frequent subject of research in evolutionary biology. In 2004, [[research]]ers at the [[Australian National University]] discovered the platypus has ten [[sex chromosome]]s, compared with two (XY) in most other mammals (for instance, a male platypus is always XYXYXYXYXY).<ref name="discover">J. Selim, [http://discovermagazine.com/2005/apr/sex-ys-platypuses0425/ "Sex, Ys, and platypuses,"] ''Discover'' April 25, 2005. Retrieved September 26, 2008.</ref> Although given the XY designation of mammals, the sex chromosomes of the platypus is more similar to the ZZ/ZW sex chromosomes found in [[bird]]s.<ref name="draft_genome">W. C. Warren, [http://www.nature.com/nature/journal/v453/n7192/abs/nature06936.html "Genome analysis of the platypus reveals unique signatures of evolution,"] ''Nature'' 453(2008)(issue 7192): 175–183. Retrieved September 26, 2008.</ref> It also lacks the mammalian sex-determining gene [[SRY]], meaning that the process of sex determination in the platypus remains unknown.<ref>Wellcome Trust Sanger Institute (WTSI) and European Bioinformatics Institute (EBI), [http://pre.ensembl.org/Ornithorhynchus_anatinus/index.html "Explore the platypus genome,"] ''Ensembl''. September 26, 2008. </ref>  
  
Because of the early divergence from the [[Theria|therian mammals]] and the low numbers of extant monotreme species, it is a frequent subject of research in evolutionary biology. In 2004, [[research]]ers at the [[Australian National University]] discovered the Platypus has ten [[sex chromosome]]s, compared with two (XY) in most other mammals (for instance, a male Platypus is always XYXYXYXYXY).<ref name="discover">{{cite web|url=http://discovermagazine.com/2005/apr/sex-ys-platypuses0425/|title=Sex, Ys, and Platypuses|publisher=Discover|author=Jocelyn Selim|date=2005-04-25| accessdate = 2008-05-07}}</ref> Although given the XY designation of mammals, the sex chromosomes of the Platypus are more similar to the ZZ/ZW sex chromosomes found in [[bird]]s.<ref name="draft_genome">{{cite journal| journal = Nature| volume = 453| issue = 7192| pages = 175–183| title = Genome analysis of the platypus reveals unique signatures of evolution| date = 2008-05-08| doi = 10.1038/nature06936| author = Warren, Wesley C.}}</ref> It also lacks the mammalian sex-determining gene [[SRY]], meaning that the process of sex determination in the Platypus remains unknown.<ref>{{cite web|url=http://pre.ensembl.org/Ornithorhynchus_anatinus/index.html|title=Explore the Platypus genome|publisher=Ensembl|date=2006-11| accessdate = 2007-01-19}}</ref> A draft version of the platypus genome sequence was published in ''[[Nature (journal)|Nature]]'' on 8 May 2008, revealing both reptilian and mammalian elements, as well as two genes found previously only in birds, amphibians and fish.<ref name="draft_genome" /> More than 80% of the Platypus' genes are common to the other mammals whose genomes have been sequenced.
+
A draft version of the platypus genome sequence was published in ''[[Nature (journal)|Nature]]'' on May 8, 2008, revealing both reptilian and mammalian elements, as well as two genes found previously only in birds, amphibians, and fish.<ref name="draft_genome" /> More than 80 percent of the platypus' genes are common to the other mammals whose genomes have been sequenced.
  
 
== Conservation status ==
 
== Conservation status ==
 +
[[Image:platypus-plate.jpg|right|200px|thumb|A depiction of a platypus from a book for children published in Germany in 1798]]
 +
Except for its loss from the state of South Australia, the platypus occupies the same general distribution as it did prior to European settlement of [[Australia]]. However, local changes and fragmentation of distribution due to human modification of its habitat are documented.
  
Except for its loss from the state of South Australia, the Platypus occupies the same general distribution as it did prior to European settlement of Australia. However, local changes and fragmentation of distribution due to human modification of its habitat are documented. Its current and historical abundance, however, is less well-known and it has probably declined in numbers, although still being considered as common over most of its current range.<ref name="HCP" /> The species was extensively hunted for its fur until the early years of the 20th century and, although protected throughout Australia in 1905,<ref name="QM" /> up until about 1950 it was still at risk of drowning in the nets of inland fisheries.<ref name="CSIRO" /> The Platypus does not appear to be in immediate danger of extinction thanks to conservation measures, but it could be impacted by habitat disruption caused by dams, irrigation, pollution, netting and trapping.<ref name="IUCN" /> The [[IUCN]] lists the Platypus on its [[Red List]] as Least Concern.<ref name="IUCN" />
+
The current and historical abundance of the platypus, however, is less well-known and it has probably declined in numbers, although still being considered as "common" over most of its current range.<ref name="HCP" /> The species was extensively hunted for its fur until the early years of the twentieth century and, although protected throughout Australia in 1905,<ref name="QM" /> up until about 1950 it was still at risk of [[drowning]] in the nets of inland [[fisheries]].<ref name="CSIRO" /> The platypus does not appear to be in immediate danger of [[extinction]] thanks to conservation measures, but it could be impacted by habitat disruption caused by [[dam]]s, [[irrigation]], [[pollution]], netting, and trapping.<ref name="IUCN" /> The [[IUCN]] lists the Platypus on its [[Red List]] as Least Concern.<ref name="IUCN" />
 
 
[[Image:platypus-plate.jpg|right|200px|thumb|A depiction of a Platypus from a book for children published in Germany in 1798]]
 
 
 
Platypuses generally suffer from few diseases in the wild; however, there is widespread public concern in Tasmania about the potential impacts of a disease caused by the fungus ''[[Mucor amphibiorum]]''. The disease (termed ''[[Mucormycosis]]'') only affects Tasmanian platypuses, and has not been observed in platypuses in mainland Australia. Affected platypuses can develop ugly skin lesions or ulcers on various parts of the body, including their backs, tails and legs. Mucormycosis can kill platypuses, death arising from secondary infection and by affecting the animals' ability to maintain body temperature and forage efficiency. The Biodiversity Conservation Branch at the Department of Primary Industries and Water are collaborating with NRM north and [[University of Tasmania]] researchers to determine the impacts of the disease on Tasmanian Platypus, as well as the mechanism of transmission and current spread of the disease.<ref name="DPIW2">{{cite web|url=http://www.dpiw.tas.gov.au/inter.nsf/WebPages/SSKA-7AH66E?open|title=Platypus Fungal Disease |publisher = Department of Primary Industries and Water, Tasmania|date=2008-08-29| accessdate = 2008-02-29}}</ref> Until recently, the introduced [[Red Fox]] (''Vulpes vulpes'') was confined to mainland Australia, but growing evidence now indicates that it is present in low numbers in Tasmania.<ref>http://www.dpiw.tas.gov.au/inter.nsf/ThemeNodes/LBUN-5K438G?open.</ref>
 
 
 
Much of the world was introduced to the Platypus in 1939 when ''[[National Geographic Magazine]]'' published an article on the Platypus and the efforts to study and raise it in captivity. This is a difficult task, and only a few young have been successfully raised since — notably at [[Healesville Sanctuary]] in [[Victoria (Australia)|Victoria]]. The leading figure in these efforts was [[David Fleay]], who established a platypussary — a simulated stream in a tank — at the Healesville Sanctuary and had a successful breeding in 1943. In 1972, he found a dead baby of about 50 days old, which had presumably been born in captivity, at his [[David Fleay Wildlife Park|wildlife park]] at [[Burleigh Heads, Queensland|Burleigh Heads]] on the [[Gold Coast, Queensland|Gold Coast]], Queensland.<ref name="DF">{{cite web|url=http://www.epa.qld.gov.au/nature_conservation/wildlife/david_fleay_wildlife_park/50_years_wild/david_fleays_achievements/|title= David Fleay's achievements|publisher=Queensland Government|date=2003-11-23| accessdate = 2006-09-13}}</ref> Healesville repeated its success in 1998 and again in 2000 with a similar stream tank. [[Taronga Zoo]] in [[Sydney]] bred twins in 2003, and had another birth in 2006.<ref name="catalyst">{{cite web|url=http://www.abc.net.au/catalyst/stories/s988946.htm|title=Platypus|publisher=Catalyst|date=2003-11-13| accessdate = 2006-09-13}}</ref>
 
 
 
== Cultural references ==
 
 
 
[[Image:Oz20cent.jpg|thumb|left|The Australian 20 cent coin features a Platypus.]]
 
  
The Platypus is sometimes jokingly referred to as proof that [[God]] has a sense of humour (at the beginning of the film ''[[Dogma (film)|Dogma]]'', for example). Its unusual appearance has led to its featuring in many media, particularly in its native Australia.
+
Platypuses generally suffer from few diseases in the wild; however, there is widespread public concern in [[Tasmania]] about the potential impacts of a disease caused by the fungus ''[[Mucor amphibiorum]].'' The disease (termed ''[[Mucormycosis]]'') only affects Tasmanian platypuses, and has not been observed in platypuses in mainland Australia. Affected platypuses can develop ugly skin lesions or ulcers on various parts of the body, including their backs, tails, and legs. Mucormycosis can kill platypuses, death arising from secondary [[infection]] and by affecting the animals' ability to maintain body temperature and forage efficiency. The Biodiversity Conservation Branch at the Department of Primary Industries and Water are collaborating with NRM north and [[University of Tasmania]] researchers to determine the impacts of the disease on Tasmanian platypus, as well as the mechanism of transmission and current spread of the disease.<ref name="DPIW2">Department of Primary Industries and Water, Tasmania, [http://www.dpiw.tas.gov.au/inter.nsf/WebPages/SSKA-7AH66E?open "Platypus fungal disease,"] ''Department of Primary Industries and Water, Tasmania''. Retrieved September 27, 2008.</ref>
  
The Platypus has been used several times as a mascot: "Syd" the Platypus was one of the three mascots chosen for the [[2000 Summer Olympics|Sydney 2000 Olympics]] along with an echidna and a [[kookaburra]],<ref>{{cite web|url=http://en.beijing2008.com/31/87/article211928731.shtml|title=A Brief History of the Olympic and Paralympic Mascots|publisher=Bejing2008|date=2004-08-05| accessdate = 2006-10-25}}</ref> "Expo Oz" the Platypus was the mascot for [[Expo '88]], which was held in [[Brisbane]] in 1988,<ref>{{cite web|url=http://www.foundationexpo88.org/aboutcontents.html|title=About World Expo '88|publisher=Foundation Expo '88|date=1988| accessdate = 2007-12-17}}</ref> and [[Hexley]] the Platypus is the mascot for [[Apple Computer]]'s [[BSD]]-based [[Darwin (operating system)|Darwin]] operating system, Mac OS X.<ref>{{cite web|url=http://www.hexley.com/|title=The Home of Hexley the Platypus| accessdate = 2006-10-25}}</ref>
+
Much of the world was introduced to the platypus in 1939 when ''[[National Geographic Magazine]]'' published an article on the platypus and the efforts to study and raise it in captivity. This is a difficult task, and only a few young have been successfully raised since&mdash;notably at [[Healesville Sanctuary]] in [[Victoria (Australia)|Victoria]]. The leading figure in these efforts was [[David Fleay]], who established a platypussary&mdash;a simulated stream in a tank&mdash;at the Healesville Sanctuary and had a successful breeding first in 1943.
 
 
The Platypus has also been featured in songs, such as [[Green Day|Green Day's]] ''Platypus (I Hate You)'' and [[Mr. Bungle]]'s ''Platypus''. It is the subject of a children's poem by [[Banjo Paterson]]<ref> {{cite web |url=http://www.middlemiss.org/lit/authors/patersonab/animalsnoahforgot/oldmanplatypus.html |title=Old Man Platypus |accessdate=2008-09-04 |author=[[Banjo Paterson]] |work=[[The Animals Noah Forgot]] |publisher=Endeavour Press |year=1933}}</ref>, and it also frequently appears as a character in children's television programs, for example, the Platypus Family on [[Mister Rogers' Neighborhood]], [[Perry the Platypus]] on the show [[Phineas and Ferb]], and Ovide, the star of the cartoon ''[[Ovide and the Gang]]''.<ref>{{cite web|url=http://www.imdb.com/title/tt0388631/|title=Ovide and the Gang|publisher=IMDB| accessdate = 2006-10-25}}</ref>
 
 
 
== See also ==
 
 
 
* [[Australian fauna]]
 
* [[List of venomous mammals]]
 
* [[Henry Burrell]]
 
  
 
== Notes ==
 
== Notes ==
{{reflist|2}}
+
<references/>
  
 
== References ==
 
== References ==
  
;Books
+
* Augee, M. L. 2001. ''Platypus.'' Chicago: World Book Encyclopedia. ISBN 071660101X.
<div class="references-small">
+
* Burrell, H. 1974. ''The Platypus.'' Adelaide: Rigby. ISBN 0851795218.
* Augee, Michael L. ''Platypus''. World Book Encyclopedia. 2001 ed.
+
* Fleay, D. H. 1980. ''Paradoxical Platypus: Hobnobbing with Duckbills.'' Jacaranda Press. ISBN 0701613645.
* Burrell, Harry ''The Platypus''. Adelaide: Rigby, 1974. ISBN 0-85179-521-8
+
* Grant, T. 1995. ''The Platypus: A Unique Mammal.'' Sydney: University of New South Wales Press. ISBN 0868401439.
* Fleay, David H. ''Paradoxical Platypus: Hobnobbing with Duckbills''. Jacaranda Press, 1980. ISBN 0-7016-1364-5.
+
* Griffiths, M. 1978. ''The Biology of the Monotremes''. New York: Academic Press. ISBN 0123038502.
* Grant, Tom ''The platypus: a unique mammal''. Sydney: University of New South Wales Press, 1995. ISBN 0-86840-143-9.
+
* Hutch, M., and M. C. McDade, eds. 2004. ''Grzimek's Animal Life Encyclopedia, Volume 12.'' Detroit: Gale. ISBN 0787657883.
* Griffiths, Mervyn. ''The Biology of the Monotremes''. Academic Press, 1978.
+
* Moyal, A. 2001. ''Platypus: The Extraordinary Story of How a Curious Creature Baffled the World.'' Smithsonian Books. ISBN 1560989777.
* Hutch, Michael and McDade, Melissa C., eds. ''Grzimek's Animal Life Encyclopedia; Volume 12.'' Detroit: Gale, 2004.
+
* Strahan, R. 1995. ''The Mammals of Australia.'' New South Wales: Reed Books. ISBN 0730104842.
* Marshall, Ben "The Amazing Duckbilled Platypus" New York Publishers Inc. 2002 ed
+
* Walton, D. and B. J. Richardson, eds. ''Fauna of Australia. Volume 1B, Mammalia.'' Canberra: Australian Govt. Pub. Service. 1989. ISBN 0644060565
* Moyal, Ann. ''Platypus: The Extraordinary Story of How a Curious Creature Baffled the World''. Smithsonian Books, 2001. ISBN 1-56098-977-7.
 
* Strahan, R. ''The Mammals of Australia''. New South Wales: Reed Books, 1995.
 
</div>
 
 
 
;Documentary
 
<div class="references-small">
 
* ''Eye of the Storm''. Documentary by the [[Australian Broadcasting Corporation]].
 
</div>
 
 
 
  
 
== External links ==
 
* [http://www.biodiversitylibrary.org/name/Ornithorhynchus_anatinus Biodiversity Heritage Library bibliography] for ''Ornithorhynchus anatinus''
 
{{commons|Ornithorhynchidae}}
 
{{wikispecies|Ornithorhynchus anatinus}}
 
 
<!-- This could probably be used as source, but is not very insightful as external link since it is very short: [http://www.amonline.net.au/factsheets/platypus.htm Platypus-Evolution and Conservation] —>
 
  
 
{{Monotremata}}
 
{{Monotremata}}
 
  
 
[[Category:Life sciences]]
 
[[Category:Life sciences]]
 
[[Category:Animals]]
 
[[Category:Animals]]
 
[[Category:Mammals]]
 
[[Category:Mammals]]
[[Category:Monotremes]]
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{{Credit|Platypus|240877686}}
 
{{Credit|Platypus|240877686}}

Latest revision as of 01:53, 10 April 2023

Platypus[1]
Ornithorhynchidae-00.jpg
Conservation status
Status iucn2.3 LC.svg
Least concern

(IUCN) [2]

Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Monotremata
Family: Ornithorhynchidae
Genus: Ornithorhynchus
Blumenbach, 1800
Species: O. anatinus
Binomial name
Ornithorhynchus anatinus
(Shaw, 1799)
Platypus range (indicated by darker shading)[3]
Platypus range (indicated by darker shading)[3]

Platypus is the common name for a semi-aquatic, egg-laying mammal, Ornithorhynchus anatinus, endemic to eastern Australia, including Tasmania, and uniquely characterized by a snout like a duck's bill, a broad and flat beaver-like tail, and webbed feet like an otter. It is one of only five extant species of monotremes (order Monotremata), the only mammals that lay eggs instead of giving birth to live young. Also known as the duck-billed platypus and the duckbill, it is the sole living representative of its family (Ornithorhynchidae) and genus (Ornithorhynchus), though a number of related species have been found in the fossil record. The platypus is one of the few venomous mammals; the male platypus has a spur on the hind foot that delivers a venom capable of causing severe pain to humans.

The bizarre appearance of this egg-laying, venomous, duck-billed, beaver-tailed, otter-footed mammal baffled European naturalists when they first encountered descriptions and a pelt, with some considering it an elaborate hoax. Despite a limited distribution, it is one of the more well-known animals worldwide given its unique features, and it is a recognizable and iconic symbol of Australia. Its singular characteristics also make the platypus an important subject in the study of evolutionary biology. Ecologically, it has an important role in food chains, feeding on freshwater shrimp, crayfish, annelids, and insect larvae, and being consumed by snakes, birds of prey, crocodiles, and other predators.

Until the early twentieth century, the platypus was hunted for its fur, but it is now protected throughout its range. Although captive breeding programs have had only limited success and the Platypus is vulnerable to the effects of pollution, it is not under any immediate threat.

The plural usually is formed as either platypuses or platypus, with either correct, although platypi also appears on occasion.

Overview and description

A color print of platypuses from 1863

The platypus and four species of echidnas ("spiny anteaters") comprise the only extant species of monotremes, the egg-laying mammals of the order Monotremata, the only order in subclass Monotremata (or Prototheria). Monotremes are one of three subdivisions of mammals, the other two being the placentals (Placentalia or Eutheria) and the marsupials (Marsupialia or Metatheria), both of which give birth to live young. The key physiological difference between monotremes and other mammals is that in monotremes the urinary, defecatory, and reproductive systems all open into a single duct, the cloaca. Other mammal females have separate openings for reproduction, urination, and defecation. Monotremes are placed in two families, with the platypus belonging to Ornithorhynchidae and the four species of echidnas in the Tachyglossidae family. Echidnas also are found in Australia, as well as New Guinea.

The squat body and the broad, flat tail of the platypus are covered with dense brown fur that traps a layer of insulating air to keep the animal warm.[3][4] The platypus uses its tail for storage of fat reserves (an adaptation also found in animals such as the Tasmanian devil[5] and fat-tailed sheep). It has webbed feet and a large, rubbery snout; these are features that appear closer to those of a duck than to those of any known mammal. Unlike a bird's beak (in which the upper and lower parts separate to reveal the mouth), the snout of the platypus is a sensory organ with the mouth on the underside. The nostrils are located on the dorsal surface of the snout, while the eyes and ears are located in a groove set just back from it; this groove is closed when swimming.[4] The webbing is more significant on the front feet and is folded back when walking on land.[4]

Weight varies considerably from 0.7 to 2.4 kilograms (1.5 to 5.3 pounds), with males being larger than females: males average 50 centimeters (20 inches) in total length while females average 43 centimeters (17 inches)[4] There is substantial variation in average size from one region to another, and this pattern does not seem to follow any particular climatic rule and may be due to other environmental factors, such as predation and human encroachment.[6]

The platypus has an average body temperature of about of about 32°C (90°F), rather than the 37°C (99°F) typical of placental mammals.[7] Research suggests this has been a gradual adaptation to harsh environmental conditions on the part of the small number of surviving monotreme species rather than a historical characteristic of monotremes.[8][9]

The modern platypus young have three-cusped molars which they lose before or just after leaving the breeding burrow;[10][11] adults have heavily keratinized pads in their place.[4] The platypus jaw is constructed differently from that of other mammals, and the jaw-opening muscle is different.[4] As in all true mammals, the tiny bones that conduct sound in the middle ear are fully incorporated into the skull, rather than lying in the jaw as in cynodonts and other pre-mammalian synapsids. However, the external opening of the ear still lies at the base of the jaw.[4] The platypus has extra bones in the shoulder girdle, including an interclavicle, which is not found in other mammals.[4] It has a reptilian gait, with legs that are on the sides of the body, rather than underneath.[4]

Venom

The calcaneus spur found on the male's hind limb is used to deliver venom.

The male platypus has ankle spurs that produce a cocktail of venom,[12][13][14] composed largely of defensin-like proteins (DLPs); the venom is unique to the platypus.[15] Although powerful enough to kill smaller animals,[15] the venom is not lethal to humans, but is so excruciating that the victim may be incapacitated. Oedema rapidly develops around the wound and gradually spreads throughout the affected limb. Information obtained from case histories and anecdotal evidence indicates that the pain develops into a long-lasting hyperalgesia that persists for days or even months.[16][17] Venom is produced in the crural glands of the male, which are kidney-shaped alveolar glands connected by a thin-walled duct to a calcaneus spur on each hind limb. The female platypus, in common with echidnas, has rudimentary spur buds that do not develop (dropping off before the end of their first year) and lack functional crural glands.[4]

The venom appears to have a different function from those produced by non-mammalian species: Its effects are not life-threatening but nevertheless powerful enough to seriously impair the victim. Since only males produce venom and production rises during the breeding season, it is theorized that it is used as an offensive weapon to assert dominance during this period.[15]

Electrolocation

Monotremes are the only mammals known to have a sense of electroreception: They locate their prey in part by detecting electric fields generated by muscular contractions. The platypus' electroreception is the most sensitive of any monotreme.[18]

The electroreceptors are located in rostro-caudal rows in the skin of the bill, while mechanoreceptors (which detect touch) are uniformly distributed across the bill. The electrosensory area of the cerebral cortex is contained within the tactile somatosensory area, and some cortical cells receive input from both electroreceptors and mechanoreceptors, suggesting a close association between the tactile and electric senses. Both electroreceptors and mechanoreceptors in the bill dominate the somatotopic map of the platypus brain, in the same way human hands dominate the Penfield homunculus map.[19][20]

The platypus can determine the direction of an electric source, perhaps by comparing differences in signal strength across the sheet of electroreceptors. This would explain the animal's characteristic side-to-side motion of its head while hunting. The cortical convergence of electrosensory and tactile inputs suggests a mechanism for determining the distance of prey items which, when they move, emit both electrical signals and mechanical pressure pulses, which would also allow for computation of distance from the difference in time of arrival of the two signals.[18]

The platypus feeds by digging in the bottom of streams with its bill. The electroreceptors could be used to distinguish animate and inanimate objects in this situation (in which the mechanoreceptors would be continuously stimulated).[18] When disturbed, its prey would generate tiny electrical currents in their muscular contractions, which the sensitive electroreceptors of the platypus could detect. Experiments have shown that the platypus will even react to an "artificial shrimp" if a small electrical current is passed through it.[21]

Ecology and behavior

The platypus is very difficult to spot even on the surface of a river.

The platypus is semi-aquatic, inhabiting small streams and rivers over an extensive range from the cold highlands of Tasmania and the Australian Alps to the tropical rainforests of coastal Queensland as far north as the base of the Cape York Peninsula.[22] Inland, its distribution is not well known: it is extinct in South Australia (barring an introduced population on Kangaroo Island) and is no longer found in the main part of the Murray-Darling Basin, possibly due to the declining water quality brought about by extensive land clearing and irrigation schemes.[23] Along the coastal river systems, its distribution is unpredictable; it appears to be absent from some relatively healthy rivers, and yet maintains a presence in others that are quite degraded (the lower Maribyrnong, for example).[24]

Its habitat bridges rivers and the riparian zone for both a food supply of prey species and banks where it can dig resting and nesting burrows.[25] It may have a range of up to 7 kilometers (4.3 miles), with male's home ranges overlapping with those of 3 or 4 females.[26]

The platypus is generally regarded as nocturnal and crepuscular, but individuals are also active during the day, particularly when the sky is overcast.[25]

The platypus is an excellent swimmer and spends much of its time in the water foraging for food. When swimming, it can be distinguished from other Australian mammals by the absence of visible ears.[27] Uniquely among mammals, it propels itself when swimming by alternate rowing motion with the front two feet; although all four feet of the Platypus are webbed, the hind feet (which are held against the body) do not assist in propulsion, but are used for steering in combination with the tail.[28] Dives normally last around 30 seconds, but can last longer although few exceed the estimated aerobic limit of 40 seconds. Ten to twenty seconds are commonly spent in recovery at the surface.[29][30] The species is endothermic, maintaining its body temperature about 32°C (90°F), lower than most mammals, even while foraging for hours in water below 5°C (41°F).[4]

The platypus is a carnivore. It feeds on annelid worms and insect larvae, freshwater shrimps, and yabbies (freshwater crayfish) that it digs out of the riverbed with its snout or catches while swimming. It utilizes cheek-pouches to carry prey to the surface where they are eaten.[27] The platypus needs to eat about twenty percent of its own weight each day. This requires the platypus to spend an average of 12 hours each day looking for food.[29] When not in the water, the platypus retires to a short, straight resting burrow of oval cross-section, nearly always in the riverbank not far above water level, and often hidden under a protective tangle of roots.[27]

Natural predators include snakes, water rats, goannas, hawks, owls, and eagles. Low platypus numbers in northern Australia are possibly due to predation by crocodiles.[31] The introduction of red foxes as a predator for rabbits may have had some impact on its numbers on the mainland.[6]

Platypuses have been heard to emit a low growl when disturbed and a range of other vocalizations have been reported in captive specimens.[3]

Reproduction and life cycle

When the platypus was first discovered, scientists were divided over whether the female laid eggs. This was not confirmed until 1884 when W. H. Caldwell was sent to Australia where, after extensive searching assisted by a team of 150 Aborigines, he managed to discover a few eggs.[4][15] Mindful of the high cost of wiring England based on the cost per word, Caldwell famously, but tersely, wired London, "Monotremes oviparous, ovum meroblastic." That is, monotremes lay eggs, and the eggs are similar to those of reptiles in that only part of the egg divides as it develops.

The species exhibits a single breeding season; mating occurs between June and October, with some local variation taking place in populations across the extent of its range.[31] Historical observation, mark and recapture studies, and preliminary investigations of population genetics indicate the possibility of resident and transient members of populations and suggest a polygynous mating system.[32] Females are thought likely to become sexually mature in their second year, with breeding confirmed to still take place in animals over nine years old.[32]

Outside the mating season, the platypus lives in a simple ground burrow whose entrance is about 30 centimeters (12 inches) above the water level. After mating, the female constructs a deeper, more elaborate burrow up to 20 meters (66 feet) long and blocked with plugs at intervals (which may act as a safeguard against rising waters or predators, or as a method of regulating humidity and temperature).[33]

The male takes no part in caring for its young, and retreats to its yearlong burrow. The female softens the ground in the burrow with dead, folded, wet leaves and she fills the nest at the end of the tunnel with fallen leaves and reeds for bedding material. This material is dragged to the nest by tucking it underneath her curled tail.[3]

The female platypus has a pair of ovaries but only the left one is functional. It lays one to three (usually two) small, leathery eggs (similar to those of reptiles), that are about 11 millimeters (0.43 inches) in diameter and slightly rounder than bird eggs.[34] The eggs develop in utero for about 28 days with only about 10 days of external incubation (in contrast to a chicken egg, which spends about 1 day in tract and 21 days externally). After laying her eggs, the female curls around them. The incubation period is separated into three parts. In the first, the embryo has no functional organs and relies on the yolk sac for sustenance. The yolk is absorbed by the developing young.[35] During the second, the digits develop, and in the last, the egg tooth appears.[36]

The newly hatched young are vulnerable, blind, and hairless, and are fed by the mother's milk. Although possessing mammary glands, the platypus lacks teats. Instead, milk is released through pores in the skin. There are grooves on the mother's abdomen that form pools of milk, allowing the young to lap it up.[3][31] After they hatch, the offspring are suckled for three to four months. During incubation and weaning, the mother initially only leaves the burrow for short periods to forage. When doing so, she creates a number of thin soil plugs along the length of burrow, possibly to protect the young from predators; pushing past these on her return forces water from her fur and allows the burrow to remain dry.[37] After about five weeks, the mother begins to spend more time away from her young and at around four months the young emerge from the burrow.[31]

In captivity, platypuses have survived to 17 years of age and tagged wild specimens have been recaptured at 11 years old. Mortality rates for adults in the wild appear to be low.[4]

History, taxonomy, and etymology

When the platypus was first discovered by Europeans in 1798, a pelt and sketch were sent back to the United Kingdom by Captain John Hunter, the second Governor of New South Wales.[38] The British scientists were at first convinced that the attributes must have been a hoax.[3] George Shaw, who in 1799 produced the first description of the animal in the Naturalist's Miscellany, stated that it was impossible not to entertain doubts as to its genuine nature, and Robert Knox believed it may have been produced by some Asian taxidermist.[39] It was thought that somebody had sewn a duck's beak onto the body of a beaver-like animal. Shaw even took a pair of scissors to the dried skin to check for stitches.[3]

The common name, platypus, is Latin derived from the Greek words πλατύς or platys, meaning "flat" or "broad," and πους or pous, meaning "foot,"—in other words, ""flat foot."[40] Shaw assigned it as a Linnaean genus name when he initially described it, but the term was quickly discovered to already belong to the wood-boring ambrosia beetle (genus Platypus).[4] It was independently described as Ornithorhynchus paradoxus by Johann Blumenbach in 1800 (from a specimen given to him by Sir Joseph Banks)[41] and following the rules of priority of nomenclature, it was later officially recognize as Ornithorhynchus anatinus.[4] The scientific name Ornithorhynchus is derived from ορνιθόρυνχος ("ornithorhynkhos"), which literally means "bird snout" in Greek, and anatinus, which means "duck-like" in Latin.

There is no universally agreed upon plural of "platypus" in the English language. Scientists generally use "platypuses" or simply "platypus." Colloquially, "platypi" is also used for the plural, although this is pseudo-Latin;[3] the Greek plural would be "platypodes." Early British settlers called it by many names, such as watermole, duckbill, and duckmole.[3] The name "platypus" is often prefixed with the adjective "duck-billed" to form duck-billed platypus, despite there being only one species of platypus.[42]

Evolution

Platypus skeleton

The platypus and other monotremes were very poorly understood and some of the nineteenth century myths that grew up around them—for example, that the monotremes were "inferior" or quasi-reptilian—still endure.[43] In fact, modern monotremes are the survivors of an early branching of the mammal tree; a later branching is thought to have led to the marsupial and placental groups.[44][43] Although in 1947, William King Gregory had theorized that placental mammals and marsupials may have diverged earlier and a subsequent branching divided the monotremes and marsupials, later research and fossil discoveries have suggested this is incorrect.[43][45]

The oldest discovered fossil of the modern platypus dates back to about 100,000 years ago, during the Quaternary period. The extinct monotremes (Teinolophos and Steropodon) were closely related to the modern platypus.[45] The fossilized Steropodon was discovered in New South Wales and is composed of an opalised lower jawbone with three molar teeth (whereas the adult contemporary platypus is toothless). The molar teeth were initially thought to be tribosphenic, which would have supported a variation of Gregory's theory, but later research has suggested that, while they have three cusps, they evolved under a separate process.[10] The fossil is thought to be about 110 million years old, which means that the platypus-like animal was alive during the Cretaceous period, making it the oldest mammal fossil found in Australia. Monotrematum sudamericanum, another fossil relative of the Platypus, has been found in Argentina, indicating that monotremes were present in the supercontinent of Gondwana when the continents of South America and Australia were joined via Antarctica (up to about 167 million years ago).[10][46]

Because of the early divergence from the therian mammals and the low numbers of extant monotreme species, it is a frequent subject of research in evolutionary biology. In 2004, researchers at the Australian National University discovered the platypus has ten sex chromosomes, compared with two (XY) in most other mammals (for instance, a male platypus is always XYXYXYXYXY).[47] Although given the XY designation of mammals, the sex chromosomes of the platypus is more similar to the ZZ/ZW sex chromosomes found in birds.[48] It also lacks the mammalian sex-determining gene SRY, meaning that the process of sex determination in the platypus remains unknown.[49]

A draft version of the platypus genome sequence was published in Nature on May 8, 2008, revealing both reptilian and mammalian elements, as well as two genes found previously only in birds, amphibians, and fish.[48] More than 80 percent of the platypus' genes are common to the other mammals whose genomes have been sequenced.

Conservation status

A depiction of a platypus from a book for children published in Germany in 1798

Except for its loss from the state of South Australia, the platypus occupies the same general distribution as it did prior to European settlement of Australia. However, local changes and fragmentation of distribution due to human modification of its habitat are documented.

The current and historical abundance of the platypus, however, is less well-known and it has probably declined in numbers, although still being considered as "common" over most of its current range.[25] The species was extensively hunted for its fur until the early years of the twentieth century and, although protected throughout Australia in 1905,[37] up until about 1950 it was still at risk of drowning in the nets of inland fisheries.[23] The platypus does not appear to be in immediate danger of extinction thanks to conservation measures, but it could be impacted by habitat disruption caused by dams, irrigation, pollution, netting, and trapping.[2] The IUCN lists the Platypus on its Red List as Least Concern.[2]

Platypuses generally suffer from few diseases in the wild; however, there is widespread public concern in Tasmania about the potential impacts of a disease caused by the fungus Mucor amphibiorum. The disease (termed Mucormycosis) only affects Tasmanian platypuses, and has not been observed in platypuses in mainland Australia. Affected platypuses can develop ugly skin lesions or ulcers on various parts of the body, including their backs, tails, and legs. Mucormycosis can kill platypuses, death arising from secondary infection and by affecting the animals' ability to maintain body temperature and forage efficiency. The Biodiversity Conservation Branch at the Department of Primary Industries and Water are collaborating with NRM north and University of Tasmania researchers to determine the impacts of the disease on Tasmanian platypus, as well as the mechanism of transmission and current spread of the disease.[50]

Much of the world was introduced to the platypus in 1939 when National Geographic Magazine published an article on the platypus and the efforts to study and raise it in captivity. This is a difficult task, and only a few young have been successfully raised since—notably at Healesville Sanctuary in Victoria. The leading figure in these efforts was David Fleay, who established a platypussary—a simulated stream in a tank—at the Healesville Sanctuary and had a successful breeding first in 1943.

Notes

  1. C. Groves, "Order Primates," "Order Monotremata," (and select other orders). Page(s) 2 in D. E. Wilson and D. M. Reeder, eds., Mammal Species of the World, 3rd edition, Johns Hopkins University Press (2005). ISBN 0801882214.
  2. 2.0 2.1 2.2 Australasian Marsupial and Monotreme Specialist Group, "Ornithorhynchus anatinus," 2007 IUCN Red List of Threatened Species (1996). Retrieved on September 25, 2008. Database entry includes a brief justification of why this species is of least concern
  3. 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 Australian Platypus Conservancy, "Platypus facts file," Australian Platypus Conservancy. Retrieved September 25, 2008.
  4. 4.00 4.01 4.02 4.03 4.04 4.05 4.06 4.07 4.08 4.09 4.10 4.11 4.12 4.13 4.14 J. R. Grant, "Chapter 16, Ornithorhynchidae,", in D. Walton, and B. J. Richardson, (eds.), Fauna of Australia. Volume 1B, Mammalia. (Canberra: Australian Govt. Pub. Service. 1989. ISBN 0644060565). Retrieved September 26, 2008.
  5. E. R. Guiler, "Tasmanian devil," pages 27 to 28 in R. Strahan, (ed.), The Australian Museum Complete Book of Australian Mammals. (Angus & Robertson 1983). ISBN 0207144540.
  6. 6.0 6.1 S. Munks, and S. Nicol, "Current research on the platypus, Ornithorhynchus anatinus in Tasmania: Abstracts from the 1999 'Tasmanian Platypus WORKSHOP'," University of Tasmania (1999). Retrieved September 25, 2008.
  7. Department of Biology, Davidson College, ["http://www.bio.davidson.edu/courses/anphys/1999/White/thermal.htm "Thermal biology of the platypus,"] Davidson College (1999). Retrieved September 25, 2008.
  8. J. M. Watson, and J. A. M. Graves, "Monotreme cell-cycles and the evolution of homeothermy," Australian Journal of Zoology 36(1988)(issue 5): 573–584. Retrieved September 25, 2008.
  9. T. J. Dawson, T. R. Grant, and D. Fanning, "Standard metabolism of monotremes and the evolution of homeothermy," Australian Journal of Zoology 27 (4)(1979): 511–515. Retrieved September 25, 2008.
  10. 10.0 10.1 10.2 R. Pascual, F. J. Goin, L. Balarino, and D. E. Udrizar Sauthier, "New data on the Paleocene monotreme Monotrematum sudamericanum, and the convergent evolution of triangulate molars," Acta Palaeontologica Polonica 47(3) (2002): 487–492.
  11. H. Rance, "Living mammals are placentals (eutheria), marsupials, and monotremes," pages 304-306 in The Age of Mammals.
  12. Australian Fauna, "Platypus (Ornithorhynchus anatinus)," Australianfauna.com (2006). Retrieved September 25, 2008.
  13. University of Sydney, "Platypus venom linked to pain relief," University of Sydney (2008). Retrieved September 25, 2008.
  14. Rainforest Australia, "Platypus poison,". Rainforest Australia.
  15. 15.0 15.1 15.2 15.3 V. B. Gerritsen, "Platypus poison," Protein Spotlight 29(2002). Retrieved September 25, 2008.
  16. G. M. de Plater, P. J. Milburn, and R. L. Martin, "Venom from the platypus, Ornithorhynchus anatinus, induces a calcium-dependent current in cultured dorsal root ganglion cells," Journal of Neurophysiology 85(2001)(issue 3): 1340–1345. Retrieved September 25, 2008.
  17. B. G. Frey, "The venom of the platypus (Ornithorhynchus anatinus), Kingsnake.com.
  18. 18.0 18.1 18.2 J. D. Pettigrew, "Electroreception in monotremes," The Journal of Experimental Biology 202(1999): 1447–1454. Retrieved September 25, 2008.
  19. J. D. Pettigrew, P. R. Manger, and S. L. Fine, "The sensory world of the platypus," Philosophical Transactions of the Royal Society of London 353(1998): 1199–1210. Retrieved September 25, 2008.
  20. R. Dawkins, The Ancestor's Tale, A Pilgrimage to the Dawn of Life (Boston: Houghton Mifflin Company, 2004). ISBN 0618005838.
  21. A. Manning, and M. S. Dawkins, An Introduction to Animal Behavior, 5th edition. (Cambridge University Press, 1998). ISBN 0521570247
  22. Department of Primary Industries and Water (DPIW), Tasmania, "Platypus," Department of Primary Industries and Water, Tasmania. Retrieved September 25, 2008.
  23. 23.0 23.1 A. Scott and T. Grant, "Impacts of water management in the Murray-Darling Basin on the platypus (Ornithorhynchus anatinus) and the water rat (Hydromus chrysogaster)," CSIRO Australia Technical Report 23/97 (1997).
  24. Australian Platypus Conservancy, "Platypus in country areas," Australian Platypus Conservancy. Retrieved September 25, 2008.
  25. 25.0 25.1 25.2 T. G. Grant, and P. D. Temple-Smith, "Field biology of the platypus (Ornithorhynchus Anatinus): Historical and current perspectives," Philosophical Transactions: Biological Sciences 353(1998)(issue 1372): 1081–1091. Retrieved September 26, 2008.
  26. J. L. Gardner and M. Serena, "Spatial-organization and movement patterns of adult male platypus, Ornithorhynchus anatinus (Monotremata, Ornithorhynchidae)," Australian Journal of Zoology 43(1995)(issue 1): 91–103. Retrieved September 26, 2008.
  27. 27.0 27.1 27.2 Parks and Wildlife Service, Tasmania, "Platypus, Ornithorhynchus anatinus," Parks and Wildlife Service, Tasmania. Retrieved September 26, 2008.
  28. F. E. Fish, R. V. Baudinette, P. B. Frappell, and M. P. Sarre, "Energetics of swimming by the platypus Ornithorhynchus Anatinus: Metabolic effort associated with rowing," The Journal of Experimental Biology 200(1997)(issue 20): 2647–2652. Retrieved September 26, 2008.
  29. 29.0 29.1 P. Bethge, "Energetics and foraging behavior of the platypus," University of Tasmania (2002).
  30. H. Kruuk, "The diving behaviour of the platypus (Ornithorhynchus anatinus) in waters with different trophic status," The Journal of Applied Ecology 30(1993)(issue 4): 592–598.
  31. 31.0 31.1 31.2 31.3 Environmental Protection Agency, "Platypus (Ornithorhynchus anatinus)," Environmental Protection Agency/Queensland Parks and Wildlife Service (2008). Retrieved September 25, 2008.
  32. 32.0 32.1 T. R. Grant, M. Griffiths, and R.M.C. Leckie, "Aspects of lactation in the platypus, Ornithorhynchus anatinus (Monotremata), in waters of Eastern New South Wales," Australian Journal of Zoology 31(1983)(issue 6): 881–889. Retrieved September 26, 2008.
  33. A. B. Sorin and P. Myers, "Family Ornithorhynchidae (platypus)," Animal Diversity Web (2001). Retrieved September 26, 2008.
  34. R. L. Hughes, and L. S. Hall, "Early development and embryology of the platypus," Philosophical Transactions of the Royal Society B: Biological Sciences 353(1998)(issue 1372): 1101–1114. Retrieved September 26, 2008.
  35. A. Moyal, "The puzzling platypus," Ockhams Razor July 22, 2001. Radio National (Australia).
  36. P. R. Manger, L. S. Hall, and J. D. Pettigrew, "The development of the external features of the platypus (Ornithorhynchus anatinus)," Philosophical Transactions: Biological Sciences 353(1998)(issue 1372): 1115–1125. Retrieved September 26, 2008.
  37. 37.0 37.1 Queensland Museum, "Egg-laying mammals," Queensland Museum. Retrieved September 26, 2008.
  38. B. K. Hall, "The paradoxical platypus," BioScience 49 (3) (1999): 211–218.
  39. A. Boese, "Duck-billed platypus," Museum of Hoaxes. Retrieved September 26, 2008.
  40. H. G. Liddell, and R. Scott. 1987. A Lexicon Abridged From Liddell and Scott's Greek-English Lexicon. (Oxford: Clarendon Press. ISBN 0199102074)
  41. W. Horky, "Platypus paradoxes," National Library of Australia 52 (2001). Retrieved September 26, 2008.
  42. P. Bethge, "Platypus," Department of Anatomy & Physiology, University of Tasmania (1997). Retrieved September 26, 2008.
  43. 43.0 43.1 43.2 J. A. W. Kirsch, and G. C. Mayer, "The platypus is not a rodent: DNA hybridization, amniote phylogeny and the palimpsest theory," Philosophical Transactions of the Royal Society: Biological Sciences 353 (1372) (1998): 1221–1237. Retrieved September 26, 2008.
  44. M. Messer, A. S. Weiss, D. C. Shaw, and M. Westerman, "Evolution of the monotremes: Phylogenetic relationship to marsupials and eutherians, and estimation of divergence dates based on α-lactalbumin amino acid sequences," Journal of Mammalian Evolution 5(1)(1998): 95–105. Retrieved September 26, 2008.
  45. 45.0 45.1 O. W. M. Rauhut, T. Martin, E. Ortiz-Jaureguizar, and P. Puerta, "The first Jurassic mammal from South America," Nature. Retrieved September 26, 2008.
  46. T. Folger, "A platypus in Patagonia: Ancient life," Discover (1993). Retrieved September 26, 2008.
  47. J. Selim, "Sex, Ys, and platypuses," Discover April 25, 2005. Retrieved September 26, 2008.
  48. 48.0 48.1 W. C. Warren, "Genome analysis of the platypus reveals unique signatures of evolution," Nature 453(2008)(issue 7192): 175–183. Retrieved September 26, 2008.
  49. Wellcome Trust Sanger Institute (WTSI) and European Bioinformatics Institute (EBI), "Explore the platypus genome," Ensembl. September 26, 2008.
  50. Department of Primary Industries and Water, Tasmania, "Platypus fungal disease," Department of Primary Industries and Water, Tasmania. Retrieved September 27, 2008.

References
ISBN links support NWE through referral fees

  • Augee, M. L. 2001. Platypus. Chicago: World Book Encyclopedia. ISBN 071660101X.
  • Burrell, H. 1974. The Platypus. Adelaide: Rigby. ISBN 0851795218.
  • Fleay, D. H. 1980. Paradoxical Platypus: Hobnobbing with Duckbills. Jacaranda Press. ISBN 0701613645.
  • Grant, T. 1995. The Platypus: A Unique Mammal. Sydney: University of New South Wales Press. ISBN 0868401439.
  • Griffiths, M. 1978. The Biology of the Monotremes. New York: Academic Press. ISBN 0123038502.
  • Hutch, M., and M. C. McDade, eds. 2004. Grzimek's Animal Life Encyclopedia, Volume 12. Detroit: Gale. ISBN 0787657883.
  • Moyal, A. 2001. Platypus: The Extraordinary Story of How a Curious Creature Baffled the World. Smithsonian Books. ISBN 1560989777.
  • Strahan, R. 1995. The Mammals of Australia. New South Wales: Reed Books. ISBN 0730104842.
  • Walton, D. and B. J. Richardson, eds. Fauna of Australia. Volume 1B, Mammalia. Canberra: Australian Govt. Pub. Service. 1989. ISBN 0644060565



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