Head to head
Koala vs Wombat
The koala and the wombat do not look much alike, one a fluffy tree-dweller, the other a stocky burrower, but they are family. Genetic and fossil evidence places them as each other's nearest living relatives, the only survivors of a once-diverse group that also included the rhino-sized Diprotodon. Both are slow, low-energy grazers of a sort, both carry their young in a backward-opening pouch, and both have teeth built to wear down and keep growing.
| Koala | Wombat | |
|---|---|---|
| Relationship | Each other's closest living relatives | Each other's closest living relatives |
| Lifestyle | Arboreal; rarely comes to the ground | Terrestrial; digs extensive burrows |
| Diet | Eucalyptus leaves, almost exclusively | Native grasses, sedges, roots, and bark |
| Energy budget | Very low; sleeps most of the day | Very low; digestion takes up to 14 days |
| Pouch | Opens rearward (a burrowing-ancestor legacy) | Opens rearward, keeping soil out while digging |
| Droppings | Small green-brown pellets | Distinctive cubes, left on rocks as markers |
| Size | About 4 to 15 kg | About 20 to 35 kg |
| Conservation | Endangered in Queensland, NSW, and the ACT | Common wombat secure; northern hairy-nosed critically endangered |
Koala vs Wombat: common questions
Are koalas and wombats really related?
Yes, and closely. They are the only two living members of the suborder Vombatiformes, which means that of all the world's marsupials, a wombat's nearest relative is a koala and vice versa. They diverged from a common ancestor perhaps 30 to 40 million years ago and then specialised in opposite directions, the koala into the trees and a eucalyptus diet, the wombat into burrows and a grazing diet. Their extinct relatives in the same group include Diprotodon, the largest marsupial that ever lived, which was built like a giant wombat and stood as tall as a person at the shoulder.
Why do both a tree-climber and a digger have backward-facing pouches?
For the wombat the reason is obvious: a pouch that opened forward would fill with soil every time the animal dug, so a rearward opening keeps the joey clean and protected during excavation. The koala's rearward pouch is harder to explain, since a tree-dwelling animal has no such problem, and it is generally read as an inherited feature from the group's common ancestor, which was probably a ground-dwelling burrower. The koala simply kept the ancestral arrangement even after it moved into the trees, and it works well enough, with a strong sphincter muscle holding the joey in.
Is a koala a bear?
No. The "koala bear" name was coined by English-speaking settlers because the animal is round, furry, and superficially bear-like, but koalas are marsupials and have nothing to do with bears, which are placental carnivorans. A koala carries its young in a pouch, has a completely different tooth and jaw arrangement suited to grinding leaves, and its closest relative is the wombat. Australian usage avoids "koala bear" for this reason, and simply says "koala".