Short-beaked Echidna
(Tachyglossus aculeatus) #64-232

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Physical characteristics and distribution

Short-beaked Echidna Tachyglossus aculeatus

The head and body length of T. aculeatus is 350-530 mm, tail length is about 90 mm, and adult weight is 2.5 - 6 kg. The body is covered with specialized hairs, or spines, which can be as long as 60 mm. They are yellow and conceal most of the body fur which is brown or black. In the Tasmanian subspecies, however, the spines are mostly covered by the fur. The underparts are spineless, but covered with thick, bristly fur. The underside of the short, stubby tail is naked.

The body of T. aculeatus is compressed dorsoventrally, with a domed back and nearly concave belly. The small head emerges from the body, seemingly without a neck and the slender snout is about half as long as the head. It is believed that the snout is strong enough to crack open hollow logs and dig through forest litter to unearth ants and termites which are then caught by the echidna's sticky tongue. All four feet have five digits and long claws which are well adapted for digging. T. aculeatus has fairly poor eyesight.

There is a single opening for the passage of urine, feces, and reproduction. The male has testes which are internal and the female only develops an abdominal pocket for the incubation of a single egg during breeding season. The height of the breeding season is July and August throughout the entire range of T. aculeatus. The gestation period is brief, lasting from 9-27 days. There is a single, large yolked egg with a leatherlike shell. This is deposited into the pouch directly from the cloaca. During the incubation period, embryogenesis occurs for 10-11 days. At birth, the baby breaks through the flexible shell of the egg with the help of an egg tooth. At 55 days old, the young is expelled from the pouch. It is left in a chosen spot while the mother hunts for food, then returns periodically to suckle her baby. The baby is weaned about 3 months after leaving the pouch.

T. aculeatus is found in a variety of habitats including rocky areas, forests, hilly tracts and sandy plains. Borrows and rock crevices provide shelter where the echidna stays until late afternoon or night. Temperatures above 32°C cause the animal to retreat, and severe heat stress occurs at sustained temperatures of 35°C or above. T. aculeatus will dig deeper into its burrow when disturbed, but of the ground proves to hard for digging, the echidna curls its entire body into a spiny ball. As long as there is a sufficient food source, T. aculeatus will not go into a torpid state. Torpor is more a result of a lack of food, primarily ants and termites, than an effect of temperature.

T. aculeatus is found in S and E New Guinea; Australia, including Kangaroo Isl (off South Australia) and Tasmania.

Description of the brain

Animal source and preparation

Our specimens were obtained by Dr. Richard Lende in order to study the patterns of organization of their sensory and motor regions of cerebral neocortex.

All specimens collected followed the same preparation and histological procedure.

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