Are Koalas Bears? Why the Koala Is a Marsupial Instead

What kind of animal is a koala?

The koala (Phascolarctos cinereus) belongs to the marsupials, one of the three main groups of living mammals. The other two are the placental mammals, which include bears, dogs and humans, and the egg-laying monotremes such as the platypus.

Within the marsupials, the koala sits in the order Diprotodontia, together with kangaroos, wallabies, possums and wombats. It is the only living member of its own family, Phascolarctidae. Its nearest relatives are the three wombat species, including the common wombat, which share the suborder Vombatiformes with the koala.

Bears, on the other hand, are placental mammals in the family Ursidae, part of the order Carnivora with cats, dogs and weasels. The marsupial and placental lineages separated more than 100 million years ago, often estimated at around 160 million years. That makes a koala about as distantly related to a brown bear as it is to a human.

Why are koalas called bears?

When Europeans arrived in eastern Australia in the late 1700s, they described many unfamiliar animals by comparing them with familiar ones. The thick fur, round ears, stocky body and lack of a tail reminded settlers of a bear cub, so they called the koala a “native bear” and later a “koala bear”.

The word “koala” itself is usually traced to the Dharug language of the Sydney region. Scientists picked up the bear comparison too: the genus name Phascolarctos, coined in 1816, comes from Greek words meaning “pouch” and “bear”. Even so, naturalists of the 1800s recognized the koala as a pouched mammal, and by the 1840s it was firmly classified among the marsupials.

Today Australian zoos, museums and conservation groups use plain “koala”, and the bear label is seen as a common mistake rather than an accepted name.

What makes the koala a marsupial?

The clearest sign is the way koalas raise their young. A female koala is pregnant for only about 33–35 days. She gives birth to a single, hairless, blind joey that weighs under 1 g (0.04 oz), roughly the size of a jelly bean.

The newborn crawls through its mother’s fur into her pouch and latches onto a teat. It stays there for about six to seven months, then rides on its mother’s back until it is weaned at about a year old. Bears are completely different: a mother bear gives birth to fully formed, furred cubs after a much longer pregnancy and has no pouch. Kangaroos raise their young the same way koalas do; see what is a baby kangaroo called?

Other marsupial features include the koala’s skull and teeth, and its hind feet, where the second and third toes are fused together. This “joined toe” pattern is shared by all members of the Diprotodontia and is used as a grooming comb.

How are koalas different from bears?

Apart from their family tree, koalas and bears live very different lives.

Even the smallest bear, the sun bear of Southeast Asia, usually weighs several times as much as an adult koala. No bear has ever lived in Australia.

Why do koalas look like bears?

The resemblance is a matter of shape, not ancestry. Both koalas and bear cubs have a compact body, a short muzzle, a big head and round ears, features that people find “cuddly”. The koala’s thick fur insulates it against cold and rain, and its short body and strong limbs suit a life of gripping tree trunks.

When unrelated animals end up looking alike, biologists call it convergence. The koala has another striking example: its fingerprints are so similar to human prints that they can be hard to tell apart, though koalas and humans are only distantly related.

Are any “bears” not really bears?

The koala is not the only animal with a misleading name. The red panda is not a bear either; it belongs to its own family, Ailuridae. The giant panda, on the other hand, really is a bear, a fact confirmed by genetic studies. Find out more in are pandas bears?

The binturong of Southeast Asia, sometimes called a “bearcat”, is neither a bear nor a cat but a relative of civets. And the “water bear” is a microscopic invertebrate, the tardigrade.