Dec 6

Marsupials are a unique group of mammals that give birth to relatively undeveloped young, which they then carry to full development in a pouch, as opposed to most other mammals who give birth to fully developed young. While most marsupial species occur in Australia and on nearby islands, there is also a second group of marsupials found in the Americas. The two orders which contain the most species are Didelphimorphia, which includes American opposums such as the bushy-tailed opossum, and Diprotodontia, which consists of well-known marsupials such as koalas and kangaroos.

Goodfellow’s tree kangaroo photo

Goodfellow’s tree kangaroo is an Endangered marsupial in the order Diprotodontia

Pouch babies

Instead of giving birth to fully developed young, marsupials typically have a pouch, or marsupium, that houses the underdeveloped infant until it is fully grown. The young are born blind and hairless but once they grow too big to be carried, they are evicted from the pouch.

Koala photo

This koala joey hitches a comfy ride in the female's pouch

Fun facts

Most of us have heard of the more common marsupials such as wombats and wallabies, but there are also many unique marsupials which possess uncommon traits. For example, the honey possum is one of only a few mammals which lives solely on nectar. Likewise, the numbat is the only solely insectivorious marsupial. You can read more about the numbat here, where it was featured as our endangered species of the week.

Numbat photo

The numbat is also special because it does not have a pouch; rather, the young attach themselves directly to the nipple

Marsupials at risk

Although many species have since died out, did you know that marsupials were historically found across the world? This may have been because marsupials have the ability to survive in a variety of habitats, and range from herbivorous to carnivorous, making them a fairly adaptable group. Today, however, many living marsupial species are threatened by loss of habitat and a variety of other factors.

Spotted-tailed quoll photo

The carnivorous spotted-tailed quoll's sharp teeth are adapted to tear meat and crush bones

The monito del monte is an interesting example, the only living member of its order, Microbiotheria, it is listed as Near Threatened on the IUCN Red List. Although native to South America, it is actually more closely related to Australian marsupials. Loss of habitat is the biggest threat to this species, and the extinction of the monito del monte would severely affect the health of the forest in which it lives. It is responsible for the dispersal of many fleshy fruit seeds, and is the only species which disperses the seeds of a particular species of mistletoe.

Monito del monte photo

A monito del monte grasping a bamboo shoot

However, habitat loss is by no means the only threat to our remaining marsupial species. The Tasmanian devil is currently facing extinction due to Devil Facial Tumor Disease, or DFTD. The cancerous disease causes tumors on the face which prevent the devils from being able to eat properly, and is actually contagious. Other marsupial species have been historically persecuted, for example, the thylacine was hunted to extinction in 1936. You can read much more about the thylacine here on the ARKive blog.

If you’d like to find out more about marsupials, why not check out our marsupial scrapbook. Let us know your favourite species, and be sure to share any interesting facts you stumble across!

Christin Knesel, Intern, Wildscreen USA