Echidna

An echidna is a small, spiny mammal from Australia and New Guinea that lays eggs. Together with the platypus it belongs to the monotremes, the only mammals alive today that hatch their young from eggs. There are four living species of echidna. The short beaked echidna (Tachyglossus aculeatus), the one shown on this page, is by far the most common and the only one found in Australia. It also lives in parts of New Guinea. The other three are long beaked echidnas of the genus Zaglossus, bigger animals that live only on New Guinea: the western, the eastern and Sir David's long beaked echidna. All three are Critically Endangered. Sir David's long beaked echidna, named after David Attenborough, had not been recorded by scientists since 1961 until camera traps filmed it in Indonesia's Cyclops Mountains in 2023. So when people talk about "the echidna", they almost always mean the short beaked species. It is the most widespread native mammal in Australia, living everywhere from snowy mountains to the desert, and it is so familiar there that its image has been on the Australian five cent coin since 1966.

The name echidna was given to the animal in the early 1800s by the French naturalist Georges Cuvier, and it comes from Greek mythology. In the old myths, Echidna was a monster that was half woman and half snake, known as the mother of monsters. Her name comes from the Greek word for viper. Cuvier never explained his choice, but the usual explanation is that the animal seemed to be a mix of two worlds, just like the monster: a furry mammal that lays eggs like a reptile. Many people believe the name means "spiny", but that is a mix up with another Greek word, ekhinos, which means hedgehog and looks very similar. So the name of one of the gentlest animals in Australia actually points to a snake monster. In Australia the echidna has many other names. Aboriginal peoples know it by different names in different languages, and it appears in many traditional stories, often explaining how it got its spines. Australians sometimes call it a spiny anteater, although it is not related to true anteaters. And because it is so loved there, it was one of the three mascots of the 2000 Sydney Olympics, a cheerful echidna named Millie.

The echidna's closest living relative is the platypus, and the two are often mentioned together because they share something no other mammal has kept: they lay eggs. Monotremes branched off from the line that led to all other mammals in the age of dinosaurs, well over 150 million years ago. Echidnas and the platypus later went their separate ways, and today they look nothing alike. The platypus is a swimmer with soft fur and a bill like a duck's, while the echidna is a spiny digger that lives on land. Yet they still have a lot in common. Both are warm blooded, both feed their young on milk without having nipples, and both have a single opening for waste and reproduction, which is exactly what the word monotreme means in Greek. Both can also sense the tiny electric fields made by moving prey: the platypus has about 40,000 electroreceptors in its bill, while the short beaked echidna has a few hundred at the tip of its snout. The echidna family once had a giant. Murrayglossus hacketti, known from fossil bones found in a cave in Western Australia, was an echidna about 1 meter (3.3 feet) long that may have weighed 20 to 30 kilograms (45 to 65 pounds). It vanished during the Pleistocene, the age of the great ice ages.

A short beaked echidna is about the size of a small cat, but much rounder and lower to the ground. Its body measures 30 to 45 centimeters (12 to 18 inches) long and it usually weighs 2 to 7 kilograms (4 to 15 pounds), although its weight can change a lot through the year. The back and sides are covered in cream colored spines with dark tips, each up to about 5 centimeters (2 inches) long. They are made of keratin, the same material as human hair and nails. Between the spines grows coarse brown or black fur, and how much of it shows depends on where the echidna lives. The Tasmanian echidna, a subspecies, has thick, long fur that can almost hide its spines, which is why most photos of "fluffy echidnas" come from Tasmania. Pale or white echidnas turn up now and then, usually because of albinism or leucism. Males carry a small spur on each hind ankle. Unlike the spur of the male platypus, it is not venomous: a 2013 study found that the milky liquid it releases during the breeding season most likely works as a scent signal. Echidnas also have one of the lowest body temperatures of any mammal, around 32°C (89°F), which is why hot weather is more dangerous for them than cold.

With its spines, small eyes and pointed face, the echidna is often mistaken for a hedgehog or a porcupine, but it is not related to either of them. Hedgehogs are placental mammals from Europe, Asia and Africa that give birth to live young, and porcupines are rodents. The echidna is a monotreme that lays eggs, and its family line split from theirs well over 150 million years ago, long before any of them had spines. The resemblance is a classic case of convergent evolution: unrelated animals that eat small prey and need protection from predators ended up with the same solution, a coat of sharp spines. Look closer and the differences are easy to spot. A hedgehog has a short nose, a mouth full of small teeth and quick little legs. An echidna has no teeth at all, a long tube shaped snout and huge digging claws, and its hind feet point backward. A frightened hedgehog rolls into a ball, while an echidna usually digs straight down or wedges itself into a crevice. Size helps too: an adult echidna weighs several times more than a hedgehog. And in Australia there is a simple rule, because there are no wild hedgehogs there: a spiny animal shuffling through the bush is an echidna.

The short beaked echidna lives across almost all of Australia, including Tasmania and Kangaroo Island, and in parts of New Guinea, both in Papua New Guinea and in Indonesia's Papua region. In Australia it is the most widespread native mammal of all. It turns up in rainforests, eucalyptus woodlands, coastal heath, the edges of farmland, the snowy Australian Alps and the deserts of the center. In New Guinea it is much rarer and less studied, with records mostly from the eastern half of the island, to the north and south of the central highlands. The secret of this huge range is a flexible lifestyle. Echidnas do not dig permanent homes. They rest under logs, in rock crevices, in hollow stumps, in dense bushes or in burrows left by other animals. They do not defend territories either: each one wanders over a large home range that overlaps with those of its neighbors. Their daily routine follows the weather. In hot places they feed at night or at dusk and shelter during the day, while in cool weather they come out in full daylight. In cold places such as Tasmania and the Alps they hibernate for several months each year, letting their body temperature fall close to that of the soil around them.

Ants and termites make up most of the echidna's diet, which explains its scientific name: Tachyglossus means "fast tongue" in Greek. It also eats earthworms, beetle larvae, moth larvae and other small invertebrates, and in some areas worms and larvae matter more than ants. An echidna has no teeth at all. Its long tongue is coated in sticky saliva and flicks in and out of the snout very quickly, picking up prey from tunnels and nests. The food is then crushed between small horny spines at the back of the tongue and the roof of the mouth. The snout does the searching. It is very sensitive to touch and smell, and its tip carries a few hundred electroreceptors that can pick up the faint electric signals of moving insects and worms in damp soil or leaf litter. Once it finds a nest, the echidna tears into it with its powerful front claws, ripping open rotting logs, packed soil and even the hard walls of termite mounds. Because it swallows plenty of soil and nest material along with its prey, a large part of an echidna's droppings is simply dirt. Feeding takes up much of its active time, and a single echidna can work its way through thousands of ants in one meal.

The spines that cover an echidna's back are its whole defense plan. Each one is a stiff, sharp shaft of keratin up to about 5 centimeters (2 inches) long, and together they turn the animal into a ball that very few predators want to bite. When something approaches, the echidna has two reliable moves. On soft ground it digs straight down at surprising speed, using all four legs at once, until its body has sunk into the earth and only a patch of spines shows above the surface. On hard ground, or when caught in the open, it curls into a tight ball and tucks its soft belly, legs and snout safely inside. It can also wedge itself into a crack between rocks or under a root and raise its spines, which makes it almost impossible to pull out. Unlike a porcupine, it cannot shoot or drop its spines on purpose. Adult echidnas have few natural predators. Dingoes, feral dogs, cats, red foxes, goannas and large birds of prey take some, and the young are the most at risk. In modern Australia the biggest dangers are cars on country roads and introduced predators, which is why so many echidnas are seen crossing roads in spring, during the breeding season.

Echidna breeding starts with one of the oddest sights in the Australian bush: the echidna train. In winter, from about June to September, a female may be followed for days by a line of several males, nose to tail, all waiting for a chance to mate. In Tasmania some females even mate while they are still sleepy from hibernation. About three weeks after mating, the female lays a single small egg with a soft, leathery shell. Before that, a temporary pouch forms on her belly, and she curls up to roll the egg straight into it. The egg is only about the size of a grape and weighs less than 2 grams. It stays in the pouch, kept warm against her body, and hatches after about ten days. Echidnas have no nipples. The hatchling drinks milk that seeps out of two patches of skin inside the pouch, called milk patches, and it is rich enough for the baby to grow very fast. A female usually raises one young every year or two, and many skip a year to recover. That slow pace is one reason echidnas need to live a long time, and why each young that survives matters so much to local populations.

A baby echidna is called a puggle. A newborn echidna is tiny: when it hatches it is only about 1.5 centimeters (half an inch) long, weighs less than half a gram, and looks more like a pink jelly bean than a spiny animal. It is blind and hairless, but it has strong front legs that let it hold on inside the pouch and find the milk patches. There it drinks and grows fast. After about 50 to 60 days the puggle starts to grow spines, and the mother no longer wants to carry it. She digs a nursery burrow, leaves the puggle inside and blocks the entrance with soil. From then on she comes back only every few days, sometimes every five days or more, to let it drink large amounts of milk at once. The puggle spends several months in that burrow, slowly getting heavier and spinier. It is finally weaned at around seven months, although in cooler areas it can take close to a year, and then it leaves the burrow to live alone. Puggles raised in zoos have made the word famous, but in the wild almost nobody gets to see one, because they spend their first months hidden in the pouch and then underground.

The short beaked echidna is not endangered. The IUCN Red List classifies it as Least Concern, with a stable population, in an assessment from 2015. Nobody has counted how many echidnas there are, but the species is common across most of Australia and is protected by law in every state and territory. That does not mean it has no problems. Cars kill many echidnas, especially in spring when males roam in search of females. Foxes, cats and dogs prey on young echidnas, and land clearing removes the logs and leaf litter they need for food and shelter. Large bushfires are another threat, because echidnas move slowly and cannot outrun a fast fire; many survive by digging in, but they then face weeks with little food. The Kangaroo Island population, a separate subspecies, lost a large part of its habitat when the 2019 and 2020 fires burned almost half of the island. In New Guinea the situation is less clear. There the species is rarer, it is hunted for its meat, and very little research has been done. The picture is far worse for its relatives: all three long beaked echidnas of New Guinea are Critically Endangered, mainly because of hunting and forest loss.