Do all marsupials have pouches?

The latest Tell Me Y episode explores why most of us think they do.

Video transcript

- Why do we think all marsupials have pouches? At school, most of us were taught that a key defining feature of marsupials is that they carry their young in their pouches. Those teachers were wrong.

If you think about it, less than half of all individual marsupials actually have a pouch. Even amongst well known species like kangaroos, koalas, and wombats, it's only the females that have them. Pouches are particularly rare amongst male marsupials. Exceptions to the rule are extinct male thylacines, or Tasmanian tigers, and male water opossums.

In Australia, a female numbats have a protective skin fold over their nipples rather than a pouch. Many types of shrew and mouse-like dasyurids, that live in Papua New Guinea and Australia, don't have them either. Over in South America, the gray short-tailed opossum also doesn't have a pouch.

What makes marsupials unique among mammals is that they have less developed placentas and give birth prematurely. With the young then suckling on their mother's nipples as they grow. The mistake about all marsupials having pouches likely derives from its Latin root word, "marsupium," which means pouch. So now you know.