Echidna: The egg-laying, milk-feeding ball of spines

The echidna is an animal that grows more astonishing the more you learn: covered in spines, it looks like a walking ball of prickles; more remarkably, it is one of the very few "egg-laying mammals". Let's meet this old friend from the story of evolution.

Its body

The echidna's back and sides are covered in stiff spines. When threatened it tenses up and curls into a spiky ball, leaving a predator nowhere to bite. If the ground is soft, it has another trick: using powerful claws, it digs straight down and vanishes into the soil within minutes, leaving only the tips of its spines showing. It has no teeth; instead, horny pads in the mouth grind its food, and its flexible tongue extends up to 18 centimetres to lap up ants and termites.

Its life and reproduction

Echidnas and platypuses are "monotremes", the most primitive living mammals. It lays eggs like a reptile yet nurses its young with milk like a mammal — a strange combination that is an important clue to how mammals evolved. It lives alone, hiding much of the day, and finds food using keen smell and touch.

Where it is found

Echidnas live in Australia and New Guinea. Their spines are a defence, and predators find them hard to bite. Because their shape and behaviour are so unusual, they are a precious species for studying the origin of mammals.

A note for grown-ups

You could talk with a child about "laying eggs and giving milk": don't all mammals give birth to live young? Yet the echidna keeps the older tradition of laying eggs. Showing a child that nature always has exceptions — and that exceptions are often the most illuminating clues — is a wonderful lesson.