Photo: Stringybark Sanctuary - Pam and Matt May

This article featured in Wildlife Lands Issue 11

The short-beaked echidna (Tachyglossus aculeatus) is one of the most widespread native Australian wildlife species, occurring almost anywhere their primary food sources, ants and termites, are located.  Also found in southeast New Guinea, the species is the only one in its genus, and together with the platypus and three species of New Guinean echidna (Zaglossus spp.), is one of the only surviving monotremes - egg laying mammals.

When fully grown, short-beaked echidnas typically weigh between 2 and 5 kg, and are 30 to 45 cm in length.  Its defensive spines are modified hairs mostly comprised of keratin, with fur between them ranging in colour from honey through black (varying with geographic location) providing insulation.  They are a solitary species, and apart from the burrow created for rearing young they have no fixed shelter or nest site, with their often overlapping range areas typically being between 40 and 60 hectares.

The anatomy of the species has a number of unusual aspects, featuring elongated, backward facing hind feet and claws and stout, strong front limbs which allow it to rapidly dig, break up wood and move stones.  By contraction of the panniculus carnosus, a layer of striated muscle covering the entire body just beneath the skin, the short-beaked echidna can defensively and characteristically change shape when threatened by rolling itself into a ball.

Well adapted to survive underground, short-beaked echidnas have a great tolerance to high levels of carbon dioxide and low levels of oxygen, adaptations doubly useful for survival in areas of frequent bushfire activity. Mucus glands on the end of their snouts act as electroreceptors, and a series of push rods (columns of flattened, spinous cells) act as mechanical sensors, completing a sophisticated array of prey detection tools.

Echidnas go into deep torpor during the winter before emerging as the temperature increases to breed, looking for a mate between May and September.  Gestation takes between 21 and 28 days, during which time the female constructs a nursery burrow.  Following the gestation period, a single, rubbery-skinned egg is laid from the female echidna's cloaca directly into a small, backward-facing pouch on her abdomen.  Ten days after it is laid, the egg hatches within the pouch and a young echidna, known as a "puggle", emerges.  After a lactation period of about 200 days, the young leave the burrow.

Although they are not threatened with extinction, anthropogenic impacts such as habitat destruction and the introduction of foreign predators and parasites continue to reduce the long-term viability of the short-beaked echidna.  Despite their spines, predators of the echidna include Tasmanian devils, dingoes, goannas, cats, and foxes.  Known for their digging abilities and strong sense of smell, goannas were likely the primary predators of the echidna prior to European settlement. Despite preying on echidnas, research has shown that the top-predator status of the dingo performs a regulatory role in many Australian ecosystems, playing a significant part in the control of feral predatory species such as cats and foxes.  As a result a healthy dingo population is not only advantageous for the short-beaked echidna, but is good news for the large majority of Australian wildlife species.