12 Facts About Marsupials

Marsupials in Australia
Photo © J und C Sohns / Getty Images.

Marsupials are a group of mammals found in Australia, New Guinea, and the Americas. They include possums, wallabies, kangaroos, and koalas. Here are 12 facts about these fascinating creatures.

1. Marsupials are divided into two basic groups

Marsupials belong to a group of mammals that includes two basic groups, the American marsupials and the Australian marsupials.

American marsupials inhabit North, South and Central America and include two basic groups, the opossums and shrew opossums.

Australian marsupials inhabit Australia and New Guinea and include animal groups such as the kangaroos, wallabies, koalas, quolls, wombats, numbats, possums, marsupial moles, bandicoots, and many others.

2. There are about 334 species of marsupials

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.

3. The smallest marsupial is the long-tailed planigale

Long-tailed planigales are tiny, nocturnal creatures that measure between 2 and 2.3 inches and weigh on average a mere 4.3 grams. Long-tailed planigales inhabit a variety of habitats in northern Australia, including clay soil woodlands, grasslands, and floodplains.

4. The largest marsupial is the red kangaroo

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 3¼ and 5¼ feet long.

5. 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.

6. One species of marsupial that inhabits South America is more closely related to Australian marsupials than American marsupials

The monito del monte, a marsupial from Argentina and Chile, is more genetically similar to Australian marsupials than it is to the American marsupials with which it shares its continent. The monito del monte's similarity to Australian marsupials supports the hypothesis that marsupials spread from South America to Australia by way of Antarctica at a time when those land masses were connected, between 100 and 65 million years ago. Fossil evidence also supports this theory.

7. Marsupials do not nourish their embryos with 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.

8. 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.

9. 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.

10. Female marsupials have a 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.

11. Marsupials move using a variety of methods

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.

12. Only one species of marsupial lives 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.

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Klappenbach, Laura. "12 Facts About Marsupials." ThoughtCo, Apr. 23, 2018, thoughtco.com/facts-about-marsupials-130401. Klappenbach, Laura. (2018, April 23). 12 Facts About Marsupials. Retrieved from https://www.thoughtco.com/facts-about-marsupials-130401 Klappenbach, Laura. "12 Facts About Marsupials." ThoughtCo. https://www.thoughtco.com/facts-about-marsupials-130401 (accessed May 25, 2018).