What Is an Echidna? Meet the Spiny Mammal That Lays Eggs

An echidna is a small, spiny mammal from Australia and New Guinea that does something almost no other mammal does: it lays eggs. Covered in sharp quills like a hedgehog but built more like an anteater, the echidna is one of only two egg-laying mammal groups left on Earth, alongside the platypus. If that sounds like a contradiction, that's because echidnas break a lot of the "rules" you'd expect a mammal to follow.

Echidnas belong to a rare group of mammals called monotremes — the only mammals that lay eggs instead of giving birth to live young. There are four echidna species alive today: the short-beaked echidna, found across Australia and parts of New Guinea, and three long-beaked echidna species, found only in the highlands of New Guinea. The short-beaked echidna is the one most people picture, and it's also the most widespread native mammal in Australia, turning up everywhere from deserts to snowy mountains.

People mix these two up constantly, but they're not related at all. Hedgehogs are placental mammals that live in Europe, Asia, and Africa. Echidnas are monotremes found only in Australia and New Guinea. The spines look similar because both animals evolved the same defense independently — it's a case of nature reaching the same solution twice, not a family connection.

An adult short-beaked echidna is about the size of a small dog, usually 14 to 17 inches long and weighing 4 to 15 pounds depending on the region. Its body is covered in cream-and-black spines up to 2 inches long, mixed with coarse fur underneath. It has a long, narrow snout that doubles as both nose and mouth, no visible ears, tiny eyes, and powerful digging claws built for tearing into logs and soil.

Echidnas eat ants, termites, and other small invertebrates, which is why they're sometimes called "spiny anteaters." They have no teeth at all. Instead, a long sticky tongue — up to 7 inches — flicks in and out of their snout up to 100 times a minute, hauling insects back to a grinding pad on the roof of the mouth. A single echidna can eat thousands of ants and termites in one feeding session.

When threatened, an echidna doesn't run. It digs straight down into loose soil, using its claws to disappear within seconds, leaving only a dome of spines exposed. On hard ground where digging isn't an option, it curls into a tight, spiky ball, much like a hedgehog would. Between the spines and the speed of that digging reflex, predators mostly leave echidnas alone.

Yes — the short-beaked echidna's snout is packed with electroreceptors that can detect the faint electrical signals given off by insect muscles underground. This is the same sense the platypus uses to hunt underwater, and echidnas are the only land mammals known to have it. It's one of the clearest signs of how closely echidnas and platypuses are related, even though one lives on land and the other in rivers.

This is the part that surprises most people. A female echidna lays a single soft, leathery egg about the size of a grape and tucks it into a temporary pouch on her belly. Ten days later, the egg hatches into a baby echidna called a puggle — blind, hairless, and roughly the size of a jellybean. The puggle stays in the pouch nursing on milk (echidnas don't have nipples; the milk seeps through patches of skin) until its spines start to grow in, usually around 6 to 8 weeks, at which point the mother moves it to a burrow for safety.

Short-beaked echidnas are remarkably adaptable. They live in rainforests, deserts, grasslands, and snow-covered mountains across Australia and lowland New Guinea. They don't build permanent dens the way many burrowing mammals do — instead, they shelter under logs, in hollow trees, rock crevices, or abandoned rabbit burrows, and dig fresh cover whenever they need it.

In colder parts of their range, such as Tasmania and the Australian Alps, echidnas go into torpor during winter — a deep, energy-saving sleep that can last for weeks at a time. Their body temperature and heart rate drop dramatically, which helps them survive months when insect prey is scarce.

The short-beaked echidna is currently listed as Least Concern, thanks to its wide range and adaptability. The three long-beaked echidna species in New Guinea are a different story — all three are threatened, largely due to habitat loss and hunting, and one species, Attenborough's long-beaked echidna, was considered lost to science for decades before being rediscovered in 2023.

An echidna is proof that mammals don't all follow the same playbook. No teeth, no live birth, a built-in electric sense, and a defense system borrowed straight from a hedgehog's — all wrapped into one quiet, ant-eating animal that's been getting by just fine in Australia for millions of years. Want to see more animals this unusual? Try the random animal generator to discover another creature that breaks the rules.

🦔 San Diego Zoo – Echidna Profile

Learn more about echidnas from one of the world's leading zoological institutions.

✓ Species information • Conservation • Zoo exhibit details

🇦🇺 Australian Wildlife & Monotremes