10 Fun Facts About Marsupials

Species Variety

There are about 99 species of American marsupials and 235 species of Australian marsupials. Of all the marsupials, the most diverse are the Diprotodontia, a group of Australian marsupials that includes about 120 species of kangaroos, possums, wombats, wallabies, and koalas.

The Smallest Marsupial

The smallest marsupial is the long-tailed planigale. It is a tiny, nocturnal creature that measures between 2 and 2.3 inches and weighs about 4.3 grams. Long-tailed planigales inhabit a variety of habitats in northern Australia, including clay soil woodlands, grasslands, and floodplains.

The Largest Marsupial

The red kangaroo is the largest marsupial. Male red kangaroos grow to be more than twice the weight of females. They are rusty red in color and weigh between 55 and 200 pounds. They measure between 3.25 and 5.25 feet long.

Marsupial Diversity

Marsupials are most diverse in Australia and New Guinea, where there are no placental mammals.

In places where placental mammals and marsupials evolved side by side for long periods of time, placental mammals often displaced marsupials through competition for similar niches.

In regions where marsupials were isolated from placental mammals, marsupials diversified. This is the case with Australia and New Guinea, where placental mammals are absent and where marsupials were allowed to diversify into a variety of different forms.

Marsupials Lack a Placenta

A major difference between marsupials and placental mammals is that marsupials lack a placenta. In contrast, placental mammals develop within the mother's womb and are nourished by a placenta. The placenta—which connects the embryo of a placental mammal to the mother's blood supply—provides the embryo with nutrients and allows for gas exchange and waste elimination.

Marsupials, in contrast, lack a placenta and are born at an earlier stage in their development than placental mammals. After birth, young marsupials continue to develop as they are nourished by their mother's milk. 

Marsupial Birth

Marsupials give birth to their young very early in their development. When they are born, marsupials exist in a nearly embryonic state. At birth, their eyes, ears, and rear limbs are poorly developed. In contrast, the structures they need to crawl to their mother's pouch to nurse are well developed, including their forelimbs, nostrils, and mouth.

Development in the Pouch

After they are born, most young marsupials continue to develop in their mother's pouch.

Young marsupials must crawl from their mother's birth canal to her nipples, which in most species are located within a pouch on her belly. Once they reach the pouch, the newborns attach themselves to the nipples and feed on their mother's milk while they continue their development.

When they reach the development of a newborn placental mammal, they emerge from the pouch.

Double Reproductive Tract

Female marsupials have two uteruses. Each one has its own lateral vagina, and young are born through a central birth canal. In contrast, female placental mammals have only one uterus and one vagina.

Marsupial Movement

Kangaroos and wallabies use their long back legs to hop. When they hop at low speeds, hopping requires considerable energy and is quite inefficient. But when they hop at high speeds, the movement becomes much more efficient. Other marsupials move by running on all four limbs or by climbing or waddling.

The Only Marsupial in North America

The Virginia opossum is the only species of marsupial that inhabits North America. Virginia opossums are solitary nocturnal marsupials and are the largest of all opossums.