Echidna

The echidna is a small, spiny, egg-laying mammal that looks like a cross between a hedgehog and an anteater and behaves like neither. It belongs to the oldest surviving branch of the mammal family tree, and it has kept a set of traits that no other mammal group has retained.

Overview

Short-beaked echidnas are the most widely distributed native mammal in Australia, found in every state and territory and in almost every habitat, from alpine snowfields to the central deserts, plus lowland New Guinea. They are shy, mostly solitary, and active whenever the temperature suits them — by day in cool weather, at dusk and dawn in the heat, and rarely seen because they freeze or dig in at the first hint of disturbance.

An ancient body plan

Echidnas and the platypus are monotremes — the only mammals that lay eggs. Echidnas also have a lower and more variable body temperature than most mammals (around 32 °C), a single rear opening called a cloaca (like a bird or reptile), and males with a spur on the hind leg, though unlike the platypus the echidna’s spur is not venomous.

The body is covered in coarse fur, with many hairs on the back and sides thickened into sharp, hollow spines. The snout is a stiff tube containing the mouth, nostrils, and a set of electroreceptors, and it has no teeth at all.

Feeding

Echidnas eat ants and termites, and in some regions beetle larvae and earthworms. An echidna breaks into a nest or log with its claws, then extends a slender tongue up to 15 cm, coated in sticky saliva and flicking in and out several times a second, to lap up the insects. It grinds the food to a paste between horny pads on the tongue and the roof of the mouth before swallowing.

Torpor and hibernation

To save energy in cold weather or drought, echidnas enter torpor, letting their body temperature fall as low as 5 °C and their heart rate drop to a few beats per minute for days or weeks at a time. Alpine echidnas hibernate through winter, and some will even go into torpor to survive bushfires, sheltering in a burrow or under a log while their metabolism idles.

Reproduction

Breeding starts with the echidna train: a female is followed nose-to-tail by a line of up to ten males, sometimes for weeks, as they compete for the chance to mate. After mating, the female lays a single egg into her temporary pouch. The puggle hatches, is carried and nursed in the pouch for around two months, and is then left in a burrow, visited every few days to feed, until it is weaned at about six months.

Threats and conservation

The short-beaked echidna is listed as Least Concern and remains common across Australia. Individual echidnas are killed by vehicles, by dogs and foxes (especially puggles and burrows), and by habitat clearing and fire, and heatwaves are a growing danger to an animal that cannot sweat or pant efficiently. But the species’ wide range, generalist diet, and ability to shut its body down through hard times make it one of Australia’s more resilient native mammals. The long-beaked echidnas of New Guinea, by contrast, are large, rare, and Critically Endangered.