Echidna

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How to read a taxoboxEchidnas[1]
Western long-beaked echidna
Western long-beaked echidna
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Monotremata
Family: Tachyglossidae
Gill, 1872
Species

Genus Tachyglossus
   T. aculeatus
Genus Zaglossus
   Z. attenboroughi
   Z. bruijnii
   Z. bartoni
   †Z. hacketti
   †Z. robustus
Genus †Megalibgwilia
   †M. ramsayi
   †M. robusta

Echidna, also known as spiny anteater, is any of the egg-laying mammals comprising the Tachyglossidae family of the order Monotremata (monotremes), characterized by a stocky build, spiny coat, short legs with strongly clawed feet, rudimentary tail, and toothless jaw with a long and sticky tongue. There are four extant (living) echidna species, that, together with the platypus, are the only surviving monotremes.

The echidna species are not related to the anteater species, even though the two groups of species share a superficial resemblance and the echidna diet consists largely of ants and termites. Echidnas live in New Guinea and Australia (including the island of Tasmania).

Contents

Echidnas exhibit bi-level functionality: The pursuit of their own needs for survival, growth, and reproduction positions them to help control populations of ants and termites while, despite their spines, echidna are prey in the food chain for various birds and mammals, such as foxes, dogs, and Tasmanian devils. Additionally, indigenous peoples and early European settlers used echidnas as a source of food, and the echidna's unique form and behaviors continue to fascinate human beings, adding to the mystery and wonder of nature.

A short-beaked echidna curled into a ball; the snout is visible on the right.

Description

Short-beaked echidna.

Echidnas are monotremes; that is, they are egg-laying mammals of the order Monotremata. Monotremes represent one of the three major subdivisions of mammals. The other two groups, the marsupials and placentals give birth to live young. The key physiological difference between monotremes and other mammals is that their urinary, defecatory, and reproductive systems all open into a single duct, the cloaca. Other mammal females have separate openings for reproduction, urination, and defecation.

Like other mammals, monotremes are warm-blooded, with a high metabolic rate (though not as high as other mammals); have hair on their bodies; produce milk to feed their young; have a single bone in their lower jaw; and have three middle ear bones.

Monotremes are divided into two families—the Tachyglossidae family comprising four extant species of echidna and the Ornithorhynchidae family with only one extant species, the platypus (Ornithorhynchus anatinus).

Echidnas are covered with coarse hair and spines. Superficially, they resemble the anteaters of South America and other spiny mammals like hedgehogs and porcupines.

Echidnas have elongated and slender snouts that have the functions of both the mouth and nose. They have very short, strong limbs with large claws and are powerful diggers. Echidnas have a tiny mouth and a toothless jaw. They feed by tearing open soft logs, anthills, and similar materials, and use their long, sticky tongue which protrudes from their snout, to collect their prey.

The short-beaked echidna's diet consists largely of ants and termites, while the three extant Zaglossus species typically eat worms and insect larvae. The long-beaked echidnas have tiny spines on their tongues that helps capture their meals. The diet of the western long-beaked echidna (Zaglossus bruijni) is almost exclusively earthworms, although they will also eat termites and other insect larva (Cross 2002). The earthworms are positioned to go front first into the snout, by the echidna wrapping its powerful tongue around the front of the worm (Cross 2002).

The echidna female lays a single soft-shelled, leathery egg twenty-two days after mating and deposits it directly into her pouch. Hatching takes ten days. The young echidna, called a puggle as with the platypus infant, then sucks milk from the pores of the two milk patches (monotremes have no nipples) and remains in the pouch for forty-five to fifty-five days, at which time it starts to develop spines. The mother digs a nursery burrow and deposits the puggle, returning every five days to suckle it until it is weaned at seven months.

Male echidnas have a four-headed penis, but only two of the heads are used during mating, with the female reproductive tract having only two branches. The other two heads "shut down" and the other two fit, with the heads being used switched each time the mammal has sex (Shultz 2007).

The echidnas are named after a monster in ancient Greek mythology.

Species

Echidnas are classified into three genera. The Zaglossus genus includes three extant species and two species known only from fossils, while only one species from the genus Tachyglossus is known. The third genus, Megalibgwilia, is only known from fossils.

Zaglossus

The three living Zaglossus species are endemic to New Guinea. They are rare and are hunted for food. They forage in leaf litter on the forest floor, eating earthworms and insects.

The eastern long-beaked echidna (Zaglossus bartoni), also known as Barton's long-beaked echidna, is found mainly in Papua New Guinea at elevations between 2000 and 3000 meters. It is the smallest member of the genus, being closer in size to the short-beaked echidna than other members of the genus. Sir David's long-beaked echidna (Zaglossus attenboroughi), also known as the Attenborough's long-beaked echidna or Cyclops long-beaked echidna, lives in the Cyclops mountains in the Papua province of Indonesia, in the western part of the island (Western New Guinea) near the cities of Sentani and Jayapura. The western long-beaked echidna is present in New Guinea in regions of elevation above 1300 meters and up to 4000 meters, with fossils also found in Australia.

The three extant species are:

  • The western long-beaked echidna (Zaglossus bruijni) of the highland forests
  • Sir David's long-beaked echidna (Zaglossus attenboroughi), recently discovered, prefers a still higher habitat
  • The eastern long-beaked echidna (Zaglossus bartoni), of which four distinct subspecies have been identified

The two fossil species are:

  • Zaglossus robustus
  • Zaglossus hacketti

Tachyglossus

In Australia, the short-beaked echidna may be found in many environments, including urban parkland such as the shores of Lake Burley Griffin in Canberra, as depicted here.

The short-beaked echidna (Tachyglossus aculeatus) is found in coastal and highland regions of southwestern New Guinea and also occurs in almost all Australian environments, from the snow-clad Australian Alps to the deep deserts of the Outback, essentially anywhere that ants and termites are available. It is the most widespread native mammal in Australia, and in coastal and highland regions of southwestern New Guinea. Its size is smaller than the Zaglossus species, and it has longer hair.

Megalibgwilia

The genus Megalibgwilia is only known from fossils:

  • Megalibgwilia ramsayi known from Late Pleistocene sites in Australia
  • Megalibgwilia robusta known from Miocene sites in Australia

Importance

Echidnas are eaten by humans, and, in particular, by indigenous peoples and the early European settlers. The meat of the western long-beaked echidna (Zaglossus bruijni), for example, is a popular food in New Guinea (Cross 2002; Augee et al. 1993; Walker 1991). Echidnas also help to control populations of prey species, and themselves serve as food for birds, foxes, cats, dogs, and the Tasmanian devil, despite their spines. However, hunting and habitat loss is causing population declines.

See also

Notes

  1. C. Groves, "Order Primates," "Order Monotremata," (and select other orders). Page(s) p. 1-2 in D. E. Wilson and D. M. Reeder, eds., Mammal Species of the World, 3rd edition, Johns Hopkins University Press (2005). ISBN 0801882214.

References

  • Augee, M. L., B. Gooden, and A. Musser. 1993. Echidnas of Australia and New Guinea. Kensington, NSW, Australia: New South Wales University Press. ISBN 0868400467.
  • Cross, D. 2002. Zaglossus bruijni (western long-beaked echidna). Animal Diversity Web. Retrieved May 09, 2008.
  • Flannery, T. F. and C. P. Groves. 1998. A revision of the genus Zaglossus (Monotremata, Tachyglossidae), with description of new species and subspecies. Mammalia 62: 367-396.
  • Nowak, R. M. 1991. Walker's Mammals of the World, 5th edition. Johns Hopkins University Press, Baltimore. ISBN 080183970X.
  • Parker, J. 2000. Echidna love trains. Scribbly Gum (ABC) online magazine. Retrieved May 9, 2008.
  • Shultz, N. 2007. Exhibitionist spiny anteater reveals bizarre penis. New Scientist. Retrieved May 9, 2008.


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