Difference between revisions of "Porpoise" - New World Encyclopedia
({{Paid}}) |
Rick Swarts (talk | contribs) |
||
| (6 intermediate revisions by 3 users not shown) | |||
| Line 1: | Line 1: | ||
| − | {{Paid}}{{Approved}}{{Images OK}}{{Submitted | + | {{Copyedited}}{{Paid}}{{Approved}}{{Images OK}}{{Submitted}} |
{{Taxobox | {{Taxobox | ||
| color = pink | | color = pink | ||
| Line 5: | Line 5: | ||
| image = Porpoise touching.jpg | | image = Porpoise touching.jpg | ||
| image_width = 225px | | image_width = 225px | ||
| − | | image_caption = ''Phocoena phocoena'' | + | | image_caption = ''Phocoena phocoena,'' harbor porpoise |
| − | | fossil_range = ?Latest [[Oligocene]] | + | | fossil_range = ?Latest [[Oligocene]] – recent |
| regnum = [[Animal]]ia | | regnum = [[Animal]]ia | ||
| phylum = [[Chordata]] | | phylum = [[Chordata]] | ||
| Line 15: | Line 15: | ||
| subdivision_ranks = [[Genus|Genera]] | | subdivision_ranks = [[Genus|Genera]] | ||
| subdivision = | | subdivision = | ||
| − | ''[[Neophocaena]] | + | ''[[Neophocaena]]''<br /> |
| − | ''[[Phocoena]] | + | ''[[Phocoena]]'' <br /> |
| − | ''[[Phocoenoides]] | + | ''[[Phocoenoides]]'' |
}} | }} | ||
| − | '''Porpoises''' are small [[cetacea]]ns of the family '''Phocoenidae''' | + | '''Porpoises''' are small [[cetacea]]ns of the family '''Phocoenidae.''' Porpoises belong to the "toothed whales" suborder Odontoceti, along with [[whale]]s and [[dolphin]]s. |
| − | Although scientifically the term porpoise should be reserved for members of the family Phocoenidae, historically the term often has been applied in common vernacular to any small cetacean, especially by sailors and fishermen (Grzimek 2004). | + | Although scientifically the term ''porpoise'' should be reserved for members of the family Phocoenidae, historically the term often has been applied in common vernacular to any small cetacean, especially by sailors and fishermen (Grzimek 2004). |
| − | Aquatic and [[fish]]-like, but in reality air-breathing [[mammal]]s, porpoises reflect the stage-by-stage nature of development seen in the [[life cycle]] of all living organisms and the [[geologic timescale]] of [[Earth]]'s history. | + | Aquatic and [[fish]]-like, but in reality air-breathing [[mammal]]s, porpoises reflect the stage-by-stage nature of development seen in the [[life cycle]] of all living organisms and the [[geologic timescale]] of [[Earth]]'s history. Considered to have developed on the foundation of terrestrial mammals millions of years ago, even the [[bone]]s in the flippers of a porpoise resemble those of the hands, forelegs, and wings of terrestrial mammals, like [[human]]s, [[ungulate]]s, and [[bat]]s. |
| − | Porpoises, divided into six [[species]], live in all [[ocean]]s, mostly near the shore, with the finless porpoise (''Neophocaena phocaenoides'') | + | Porpoises, divided into six [[species]], live in all [[ocean]]s, mostly near the shore, with the finless porpoise (''Neophocaena phocaenoides'') having populations that also live in freshwater environments. Probably best known is the [[harbor porpoise]] (''Phocoena phocoena''), which can be found across the Northern Hemisphere. The vaquita (''Phocoena sinus'') is seriously [[endangered species|endangered]] as a result of chemical pollution, habitat loss, and being caught in fishermen's nets. |
==Overview== | ==Overview== | ||
| − | As [[mammal]]s, | + | As [[mammal]]s, [[cetacean]]ns are [[warm-blooded]], breathe air, and feed their young on [[milk]]. They give birth to live young, as with most mammals (except [[monotreme]]s). [[Hair]], a characteristic of mammals, is present in porpoises at least in some stage in their development, but they are nearly hairless, like other cetaceans. They also share with other cetaceans a fusiform (spindle-shaped) body with anterior limbs in the form of flippers, and a flat, notched tail with horizontal flukes that lacks bony support. |
Like other members of the Odontoceti suborder, porpoises have only one blowhole and have the main bones of the upper jaw thrust upward and back over the eye sockets (Grzimek 2004). | Like other members of the Odontoceti suborder, porpoises have only one blowhole and have the main bones of the upper jaw thrust upward and back over the eye sockets (Grzimek 2004). | ||
| − | In common use, the term porpoise is often applied to [[dolphin]]s. There is no strict definition of the term dolphin (Grzimek 2004), but it generally is used either for members of the Odontoceti family [[Delphinidae]] or for any member of the families | + | In common use, the term ''porpoise'' is often applied to [[dolphin]]s. There is no strict definition of the term ''dolphin'' (Grzimek 2004), but it generally is used either for members of the Odontoceti family [[Delphinidae]] or for any member of the families Delphinidae and [[Platanistoidea]]. |
| − | Porpoises tend to be smaller but stouter than dolphins. They have small, rounded heads and blunt jaws instead of beaks like the Delphinidae. While delphinids typically have a round, bulbous "melon," a round organ used in echolocation, most porpoises lack a melon. Phocoenid | + | Porpoises tend to be smaller but stouter than dolphins. They have small, rounded heads and blunt jaws instead of beaks like the Delphinidae. While delphinids typically have a round, bulbous "melon," a round organ used in [[echolocation]], most porpoises lack a melon. Phocoenid [[tooth|teeth]] are flattened and spade-shaped, whereas dolphins have conical teeth. |
In addition, a porpoise's dorsal fin is generally triangular, rather than curved like that of many dolphins and large [[whale]]s. (Some Delphinidae and Phocoenidae lack dorsal fins.) Some phocoenid species have small bumps, known as tubercles, on the leading edge of the dorsal fin. The function of these bumps is unknown (Read 1999). | In addition, a porpoise's dorsal fin is generally triangular, rather than curved like that of many dolphins and large [[whale]]s. (Some Delphinidae and Phocoenidae lack dorsal fins.) Some phocoenid species have small bumps, known as tubercles, on the leading edge of the dorsal fin. The function of these bumps is unknown (Read 1999). | ||
| − | Porpoises are the smallest | + | Porpoises are the smallest cetaceans, reaching body lengths up to 2.5 m (8 feet). They are [[intelligence|intelligent]] and friendly mammals. Because of their small size, porpoises lose body heat to the water more rapidly than other cetaceans. Their stout shape, which minimizes surface area, may be an adaptation to reduce heat loss. Thick [[blubber]] also insulates them from the cold. The small size of porpoises requires them to eat frequently, rather than depending on fat reserves (Read 1999). |
| − | Porpoises, along with whales and dolphins, are descendants of land-living mammals and | + | Porpoises, along with whales and dolphins, are considered to be descendants of land-living mammals and to be related to [[ungulate|hoofed animals]]. It is believed that they entered the water roughly 50 million years ago. |
==Types and distribution== | ==Types and distribution== | ||
| Line 50: | Line 50: | ||
** '''Suborder [[Mysticeti]]''': Baleen whales | ** '''Suborder [[Mysticeti]]''': Baleen whales | ||
** '''Suborder [[Odontoceti]]''': toothed whales | ** '''Suborder [[Odontoceti]]''': toothed whales | ||
| − | *** Family [[Phocoenidae]] | + | *** Family [[Phocoenidae]]: [[Porpoise]]s |
| − | **** Genus ''[[Neophocaena]] | + | **** Genus ''[[Neophocaena]]'' |
| − | ***** [[Finless Porpoise]] | + | ***** [[Finless Porpoise]], ''Neophocaena phocaenoides'' |
| − | **** Genus ''[[Phocoena]] | + | **** Genus ''[[Phocoena]]'' |
| − | ***** [[Spectacled Porpoise]] | + | ***** [[Spectacled Porpoise]], ''Phocoena dioptrica'' |
| − | ***** [[Harbor Porpoise]] | + | ***** [[Harbor Porpoise]], ''Phocoena phocaena'' |
| − | ***** [[Vaquita]] | + | ***** [[Vaquita]], ''Phocoena sinus'' |
| − | ***** [[Burmeister's Porpoise]] | + | ***** [[Burmeister's Porpoise]], ''Phocoena spinipinnis'' |
| − | **** Genus ''[[Phocoenoides]] | + | **** Genus ''[[Phocoenoides]]'' |
| − | ***** [[Dall's Porpoise]] | + | ***** [[Dall's Porpoise]], ''Phocoenoides dalli'' |
| − | Burmeister's porpoises are found in sub-Antarctic and temperate coastal waters of southern South America, while the spectacled porpoise has been spotted in a variety of locations, but seems to be most common in the southern Atlantic coast of South America (WDCS 2007). On the other hand, Dall's porpoise is found north of the | + | Burmeister's porpoises are found in sub-Antarctic and temperate coastal waters of southern [[South America]], while the spectacled porpoise has been spotted in a variety of locations, but seems to be most common in the southern Atlantic coast of South America (WDCS 2007). On the other hand, Dall's porpoise is found north of the equator, being located in the warm temperate and sub-arctic waters of the North [[Pacific Ocean]] (WDCS 2007). The well-known harbor porpoise is found in the sub-arctic and cool temperate coastal waters of the North Pacific and North [[Atlantic Ocean|Atlantic]], and is the only member of the family found in [[Europe]]an waters (WDCS 2007). The finless porpoise is found in both marine environments and freshwater. There are three varieties known, with one living in the [[Yangtze River]] of [[China]], one in coastal waters around [[Japan]] and [[Korea]], and one living in coastal and riverine waters in areas of [[Asia]] (WCDS 2007). |
| − | The vaquita is only found in the northern end of the Gulf of California (Sea of Cortez), being confined to a 30 mile radius; it is on the brink of [[extinction]], having a population estimated at only between 100 and 500 individuals (WCDS 2007). | + | The vaquita is only found in the northern end of the Gulf of California (Sea of Cortez), being confined to a 30-mile radius; it is on the brink of [[extinction]], having a population estimated at only between 100 and 500 individuals (WCDS 2007). |
| − | Recently | + | Recently discovered [[hybrid]]s between male harbor porpoises and female Dall's porpoises indicate that the two species may actually be members of the same [[genus]] (Read 1999). |
==Lifecycle and behavior== | ==Lifecycle and behavior== | ||
Porpoises are relatively [[R/K selection theory|r-selected]] compared with dolphins: that is, they rear young more quickly than dolphins. Female Dall's and harbor porpoises often become pregnant with a single calf each year, and pregnancy lasts for about 11 months. Although the lifespan of most species is not known, specimens older than in their mid-teens have rarely been found (Reed 1999). | Porpoises are relatively [[R/K selection theory|r-selected]] compared with dolphins: that is, they rear young more quickly than dolphins. Female Dall's and harbor porpoises often become pregnant with a single calf each year, and pregnancy lasts for about 11 months. Although the lifespan of most species is not known, specimens older than in their mid-teens have rarely been found (Reed 1999). | ||
| − | [[Image:Two Dalls Porpoises.JPG|thumb|right|250px|"Rooster tail" spray around swimming [[Dall's | + | [[Image:Two Dalls Porpoises.JPG|thumb|right|250px|"Rooster tail" spray around swimming [[Dall's porpoise]]s]] |
| − | Porpoises are predators of [[fish]], [[squid]], and [[crustacean]]s. Although they are capable of dives up to 200 m, they generally hunt in shallow coastal waters. They are found most commonly in small groups of fewer than ten individuals. Rarely, some species form brief aggregations of several hundred animals. Like all [[Odontoceti|toothed whales]], porpoises are capable of [[ | + | Porpoises are predators of [[fish]], [[squid]], and [[crustacean]]s. Although they are capable of dives up to 200 m, they generally hunt in shallow coastal waters. They are found most commonly in small groups of fewer than ten individuals. Rarely, some species form brief aggregations of several hundred animals. Like all [[Odontoceti|toothed whales]], porpoises are capable of [[echolocation]] for finding prey and group coordination. |
Porpoises are fast swimmers. [[Dall's porpoise]] is said to be one of the fastest cetaceans, with a speed of 55 km/h (15 m/s). | Porpoises are fast swimmers. [[Dall's porpoise]] is said to be one of the fastest cetaceans, with a speed of 55 km/h (15 m/s). | ||
| Line 92: | Line 92: | ||
== References == | == References == | ||
| − | * Grzimek, B., D. G. Kleiman, V. Geist, and M. C. McDade. 2004. ''Grzimek's Animal Life Encyclopedia'' | + | * Grzimek, B., D. G. Kleiman, V. Geist, and M. C. McDade. 2004. ''Grzimek's Animal Life Encyclopedia.'' Detroit: Thomson-Gale. ISBN 0787657883 |
| − | * Read, A. 1999. ''Porpoises'' | + | * Read, A. 1999. ''Porpoises.'' Stillwater, MN: Voyageur Press. ISBN 0896584208 |
| − | * Whale and Dolphin Conservation Society (WDCS). 2007. [http://www.wdcs.org/dan/publishing.nsf/allweb/A5343454B1CC4C0C802568F8004E6921 Porpoises] | + | * Whale and Dolphin Conservation Society (WDCS). 2007. [http://www.wdcs.org/dan/publishing.nsf/allweb/A5343454B1CC4C0C802568F8004E6921 Porpoises.] Whale and Dolphin Conservation Society. Retrieved March 25, 2007. |
{{Cetaceans}} | {{Cetaceans}} | ||
| + | [[Category:Life sciences]] | ||
| + | [[Category:Animals]] | ||
| + | [[Category:Mammals]] | ||
| − | |||
{{credit|115720340}} | {{credit|115720340}} | ||
Latest revision as of 15:09, 7 September 2009
| Porpoises
| ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
 Phocoena phocoena, harbor porpoise
| ||||||||||
| Scientific classification | ||||||||||
| ||||||||||
|
Neophocaena |
Porpoises are small cetaceans of the family Phocoenidae. Porpoises belong to the "toothed whales" suborder Odontoceti, along with whales and dolphins.
Although scientifically the term porpoise should be reserved for members of the family Phocoenidae, historically the term often has been applied in common vernacular to any small cetacean, especially by sailors and fishermen (Grzimek 2004).
Aquatic and fish-like, but in reality air-breathing mammals, porpoises reflect the stage-by-stage nature of development seen in the life cycle of all living organisms and the geologic timescale of Earth's history. Considered to have developed on the foundation of terrestrial mammals millions of years ago, even the bones in the flippers of a porpoise resemble those of the hands, forelegs, and wings of terrestrial mammals, like humans, ungulates, and bats.
Porpoises, divided into six species, live in all oceans, mostly near the shore, with the finless porpoise (Neophocaena phocaenoides) having populations that also live in freshwater environments. Probably best known is the harbor porpoise (Phocoena phocoena), which can be found across the Northern Hemisphere. The vaquita (Phocoena sinus) is seriously endangered as a result of chemical pollution, habitat loss, and being caught in fishermen's nets.
Overview
As mammals, cetaceanns are warm-blooded, breathe air, and feed their young on milk. They give birth to live young, as with most mammals (except monotremes). Hair, a characteristic of mammals, is present in porpoises at least in some stage in their development, but they are nearly hairless, like other cetaceans. They also share with other cetaceans a fusiform (spindle-shaped) body with anterior limbs in the form of flippers, and a flat, notched tail with horizontal flukes that lacks bony support.
Like other members of the Odontoceti suborder, porpoises have only one blowhole and have the main bones of the upper jaw thrust upward and back over the eye sockets (Grzimek 2004).
In common use, the term porpoise is often applied to dolphins. There is no strict definition of the term dolphin (Grzimek 2004), but it generally is used either for members of the Odontoceti family Delphinidae or for any member of the families Delphinidae and Platanistoidea.
Porpoises tend to be smaller but stouter than dolphins. They have small, rounded heads and blunt jaws instead of beaks like the Delphinidae. While delphinids typically have a round, bulbous "melon," a round organ used in echolocation, most porpoises lack a melon. Phocoenid teeth are flattened and spade-shaped, whereas dolphins have conical teeth.
In addition, a porpoise's dorsal fin is generally triangular, rather than curved like that of many dolphins and large whales. (Some Delphinidae and Phocoenidae lack dorsal fins.) Some phocoenid species have small bumps, known as tubercles, on the leading edge of the dorsal fin. The function of these bumps is unknown (Read 1999).
Porpoises are the smallest cetaceans, reaching body lengths up to 2.5 m (8 feet). They are intelligent and friendly mammals. Because of their small size, porpoises lose body heat to the water more rapidly than other cetaceans. Their stout shape, which minimizes surface area, may be an adaptation to reduce heat loss. Thick blubber also insulates them from the cold. The small size of porpoises requires them to eat frequently, rather than depending on fat reserves (Read 1999).
Porpoises, along with whales and dolphins, are considered to be descendants of land-living mammals and to be related to hoofed animals. It is believed that they entered the water roughly 50 million years ago.
Types and distribution
There are six species of phocoenids typically recognized: Burmeister's porpoise (Phocoena spinipinnis), Dall's porpoise (Phocoenoides dalli), finless porpoise (Neophocaena phocaenoides), harbor porpoise (Phocoena phocoena), spectacled porpoise (Australophocaena dioptrica or Phocoena dioptrica), and vaquita (Phocoena sinus). One taxonomy is as follows:
- ORDER CETACEA
- Suborder Mysticeti: Baleen whales
- Suborder Odontoceti: toothed whales
- Family Phocoenidae: Porpoises
- Genus Neophocaena
- Finless Porpoise, Neophocaena phocaenoides
- Genus Phocoena
- Spectacled Porpoise, Phocoena dioptrica
- Harbor Porpoise, Phocoena phocaena
- Vaquita, Phocoena sinus
- Burmeister's Porpoise, Phocoena spinipinnis
- Genus Phocoenoides
- Dall's Porpoise, Phocoenoides dalli
- Genus Neophocaena
- Family Phocoenidae: Porpoises
Burmeister's porpoises are found in sub-Antarctic and temperate coastal waters of southern South America, while the spectacled porpoise has been spotted in a variety of locations, but seems to be most common in the southern Atlantic coast of South America (WDCS 2007). On the other hand, Dall's porpoise is found north of the equator, being located in the warm temperate and sub-arctic waters of the North Pacific Ocean (WDCS 2007). The well-known harbor porpoise is found in the sub-arctic and cool temperate coastal waters of the North Pacific and North Atlantic, and is the only member of the family found in European waters (WDCS 2007). The finless porpoise is found in both marine environments and freshwater. There are three varieties known, with one living in the Yangtze River of China, one in coastal waters around Japan and Korea, and one living in coastal and riverine waters in areas of Asia (WCDS 2007).
The vaquita is only found in the northern end of the Gulf of California (Sea of Cortez), being confined to a 30-mile radius; it is on the brink of extinction, having a population estimated at only between 100 and 500 individuals (WCDS 2007).
Recently discovered hybrids between male harbor porpoises and female Dall's porpoises indicate that the two species may actually be members of the same genus (Read 1999).
Lifecycle and behavior
Porpoises are relatively r-selected compared with dolphins: that is, they rear young more quickly than dolphins. Female Dall's and harbor porpoises often become pregnant with a single calf each year, and pregnancy lasts for about 11 months. Although the lifespan of most species is not known, specimens older than in their mid-teens have rarely been found (Reed 1999).
Porpoises are predators of fish, squid, and crustaceans. Although they are capable of dives up to 200 m, they generally hunt in shallow coastal waters. They are found most commonly in small groups of fewer than ten individuals. Rarely, some species form brief aggregations of several hundred animals. Like all toothed whales, porpoises are capable of echolocation for finding prey and group coordination.
Porpoises are fast swimmers. Dall's porpoise is said to be one of the fastest cetaceans, with a speed of 55 km/h (15 m/s).
Unlike the delphinids, which often leap out the water and bow-ride on the wave of a ship, phocoenids rarely are observed doing this. Porpoises tend to be less acrobatic and more wary than dolphins.
Human impact
Accidental entanglement (bycatch) in fishing nets is the main threat to porpoises today. The vaquita, with its limited distribution in a highly industrialized area, also faces problems from habitat loss and chemical pollution.
In some countries, porpoises are hunted for food or bait meat.
Porpoises are rarely held in captivity in zoos or oceanaria, as they are generally not as capable of adapting to tank life nor as easily trained as dolphins.
See also
ReferencesISBN links support NWE through referral fees
- Grzimek, B., D. G. Kleiman, V. Geist, and M. C. McDade. 2004. Grzimek's Animal Life Encyclopedia. Detroit: Thomson-Gale. ISBN 0787657883
- Read, A. 1999. Porpoises. Stillwater, MN: Voyageur Press. ISBN 0896584208
- Whale and Dolphin Conservation Society (WDCS). 2007. Porpoises. Whale and Dolphin Conservation Society. Retrieved March 25, 2007.
| Cetaceans | |
|---|---|
| Suborder Mysticeti (baleen whales) |
Eschrichtiidae (gray whales) · Balaenopteridae (rorquals) · Balaenidae (right whales) · Neobalaenidae (pygmy right whales) |
| Suborder Odontoceti (toothed whales) |
Platanistoidea (river dolphins) · Delphinidae (oceanic dolphins) · Phocoenidae (porpoises) · Monodontidae (beluga and narwhal) · Physeteridae (sperm whales) · Kogiidae (pygmy and dwarf sperm whales) · Ziphiidae (beaked whales) |
Credits
New World Encyclopedia writers and editors rewrote and completed the Wikipedia article in accordance with New World Encyclopedia standards. This article abides by terms of the Creative Commons CC-by-sa 3.0 License (CC-by-sa), which may be used and disseminated with proper attribution. Credit is due under the terms of this license that can reference both the New World Encyclopedia contributors and the selfless volunteer contributors of the Wikimedia Foundation. To cite this article click here for a list of acceptable citing formats.The history of earlier contributions by wikipedians is accessible to researchers here:
The history of this article since it was imported to New World Encyclopedia:
Note: Some restrictions may apply to use of individual images which are separately licensed.
