Giant anteater

Giant anteater
Conservation status
Vulnerable  (IUCN 3.1)
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Superorder:	Xenarthra
Order:	Pilosa
Suborder:	Vermilingua
Family:	Myrmecophagidae
Genus:	Myrmecophaga Linnaeus, 1758
Species:	M. tridactyla
Binomial name
Myrmecophaga tridactyla Linnaeus, 1758
Giant anteater range (blue — extant, orange — possibly extinct)

The giant anteater, Myrmecophaga tridactyla, is the largest species of anteater. It is the only species in the genus Myrmecophaga. It is found in Central and South America from Honduras to northern Argentina. Its fossil remains have been found as far north as northwestern Sonora, Mexico.

It is a solitary animal, found in many habitats, including grasslands, deciduous forests and rainforests. It feeds mainly on ants and termites, sometimes up to 30,000 insects in a single day.

The genus name Myrmecophaga is from Greek murmekos, ant, and phagein, to eat.

Physiology

The giant anteater is one of a few taxa of mammals without any teeth even in a mature state. An anteater instead crushes insects it consumes using hard growths found on the inside of its mouth, and its flabby stomach. Sand and small rocks have also been found in anteaters' stomachs, suggesting these are ingested to aid digestion (possible gastroliths). They have an average body temperature of 32.7°C, which is one of the lowest of all land-living mammals. This low rate of metabolism, common in xenarthrans, means it is inactive for a mammal. Unlike most mammals, the giant anteater's gastric acid does not contain hydrochloric acid; rather, it uses formic acid produced by its prey.

It grows to a size of up to 7 feet (2.1 m) in length, with a 4-foot-long (1.2 m) head and torso, and a 3-foot-long (0.91 m) tail. Generally it weighs from 65 to 140 pounds (29 to 64 kg).

The giant anteater is covered with stiff, straw-like hair which grows up to 40 cm long on the tail. Young have soft hair until they are mature. The dominant colouring may be grey or brown, but all have a diagonal black and white shoulder stripe.

The giant anteater is generally acknowledged to have a very keen sense of smell, used to locate ants, but is thought to have poor sight and hearing.

The giant anteater does not sleep in any fixed place, instead curling up in abandoned burrows and hollows. It covers its body with its long, bushy tail to sleep.

In the wild, it is nocturnal (or active at night) near human settlements, and diurnal (active during the day) elsewhere. It stays mainly on dry ground, but is a strong and capable swimmer.

When threatened, it does not always flee, but sometimes may stand up on its hind legs, using its tail to aid balance, and strike extremely rapidly with its claws or "hugs" attackers much like a bear. An adult anteater is capable of fending off or even killing its main predators, such as the cougar.

Anatomy

A skeleton showing forelimbs resting on their knuckles

Despite its name, Myrmecophaga tridactyla, from the Greek meaning 'three-fingered ant eater', the anteater has five digits on each foot; however, the middle three digits of the forefeet have elongated claws. These are extremely strong and are used to break open ant and termite mounds to feed, and provide effective defense against predators. The anteater walks on its knuckles to protect them, giving it a shuffling gait. Their wrist bones are adapted for knuckle-walking in much the same way as those of chimpanzees. The forefeet also have one other smaller claw, and the rear feet have five small claws.

The anteater's tongue can reach 2 feet (61 cm) in length, but has a width of only 1⁄2 inch (13 mm). The anteater can cover its tongue in a sticky saliva, allowing it to trap ants, and can extend and withdraw it up to 150 times per minute. Pangolins, the giant anteater, and the tube-lipped nectar bat all have developed tongues which are detached from their hyoid bones and extend past their pharanges deep into the thorax, an example of convergent evolution. This extension lies between the sternum and the trachea.

Reproduction

Giant anteater with offspring clinging to her back

Breeding occurs year-round in captivity and the wild, though seasonal breeding times have been reported in portions of their range. Gestation is approximately 190 days, after which females give birth to a single young that weighs about 2.8 lb (1.3 kg), and it will stay near the mother until she becomes pregnant again. Females give birth standing up, and the newborn anteater immediately climbs onto her back. It will spend much of the first part of its life riding on its mother's back, until it is nearly half her size.

Young are born with a full coat of hair and adult-like markings. They are weaned around six months of age. Interbirth intervals can be as low as nine months. Sexual maturity is reached between 2.5 and 4.0 years. The mammary glands are lateral to the 'armpits' on the chest.

Communication and perception

Most communication occurs between young and their mothers or during fighting. It consists of snorts, sniffs, and hisses, as well as roaring during fights.

Food habits

Giant anteaters eat ants, termites and soft-bodied grubs. Using the long, sharp claws on their forelimbs, they open insect colonies and tree trunks. They then use their tongues to collect the eggs, larvae, and adult insects. The salivary glands secrete sticky saliva during feeding that coats the tongue. They only stay at one ant colony for a short period of time to avoid soldier ants, but giant anteaters can consume a few thousand insects in minutes. The tongue is attached to the sternum and moves very quickly, flicking 150 times per minute. They will eat fruit and birds' eggs on occasion.

Threats

File:Pumaantbear.jpg

Illustration of an anteater attacked by a cougar

Their size makes giant anteaters invulnerable to all but the largest of predators; the jaguar (Panthera onca) and the cougar (Puma concolor) are their only known predators. Anteaters use their immense front claws to defend themselves from predators, but their typical response to threat is to run away. They are often killed by humans, either intentionally through hunting or unintentionally through collisions with cars. In April 2007, an anteater at the Florencio Varela Zoo near Buenos Aires, Argentina attacked Melisa Casco, a zookeeper, mauling her abdomen and legs with its sharp front claws. The 19-year old zookeeper was admitted to the hospital in critical condition and died following leg amputation surgery.

Conservation status

Habitat destruction is the primary threat to giant anteaters. They are listed as Appendix II by the Convention on International Trade in Endangered Species (CITES). Appendix II is defined as a species not necessarily threatened to extinction, but should be controlled in trade to avoid overuse. They are listed as vulnerable by the International Union for Conservation of Nature and Natural Resources. 'Vulnerable' is defined as an estimated population reduction of 20% in the next 10 years. An estimated as few as 5,000 are left in the wild, and only 90 live in zoos across the United States. The Nashville Zoo holds the largest collection of captive giant anteaters in the world, with 11 individuals currently residing at the zoo. Nashville Zoo is also the largest and most successful breeding facility for the species worldwide, with Nashville-born individuals now residing in Thailand, France, Washington D.C and Florida.

References

• Louise H. Emmons and Francois Feer, 1997 – Neotropical Rainforest Mammals, A Field Guide.

External links

• The Online Anteater: information, images, fun facts, and other stuff about the giant anteater
• ARKive – images and movies of the giant anteater.

Gallery

• 
  At Reid Park Zoo, Tucson, Arizona
• 
  Dictionary illustration
• 
  In San Francisco Zoo
• Giant Anteater in captivity in Ueno Zoo in Japan (video)
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  Giant Anteater (Myrmecophaga tridactyla) in the Pantanal Region, Brazil