Australasian Carnivorous Marsupials: Dasyuromorphia

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AUSTRALASIAN CARNIVOROUS MARSUPIALS: Dasyuromorphia

PHYSICAL CHARACTERISTICS

Most familiar mammals such as cats, dogs, and horses are called eutherian (yoo-THEER-ee-an) mammals. These mammals have a placenta, an organ that grows in the mother's uterus (womb) and lets the mother and developing offspring share food and oxygen. Marsupials do not have a developed placenta. Because of this, they give birth to young that are physically immature and undeveloped. The young are not able to survive on their own. Instead, they are carried around for several months in their mother's pouch, or they are attached to the mother's teats, or nipples, outside the pouch, and carried until they have grown and matured enough to fend for themselves. The Australasian (living in Australia and nearby islands) carnivorous marsupials are made up of three families of marsupial mammals with a total of about seventy-one species.

Australasian carnivorous marsupials vary widely in weight, from less than one ounce (28 grams) to more that 65 pounds (30 kilograms). The combined length of their head and body ranges from less than 2 inches (5 centimeters) to 51 inches (130 centimeters). The largest Australasian carnivorous marsupial, the Tasmanian wolf, became extinct in the early 1900s. The largest living member of the Dasyuromorphia order is the Tasmanian devil.

Australasian carnivorous marsupials are all four-footed, with four toes on each of the two front feet and either four or five toes on each of the two back feet. On each back foot is a toe called a hallux (HAL-lux) that does not have a claw. Species that live mainly in trees tend to have wider feet than ground-dwelling species and use their hallux to help them grip branches. The tails of Australasian carnivorous marsupials vary in length. Some species have tails nearly as long as their bodies. All of these animals have pointed snouts and a combination of sharp pointed teeth and grinding teeth to help them eat meat.

The fur of carnivorous marsupials ranges from grayish or reddish brown to sand colored, depending on the habitat in which they live. A few have black fur, and some species have underbellies that differ slightly in color from the rest of their fur. The fur on the bodies and heads is usually short, but the fur on the tail can be either very short or very bushy. Some of the animals in this order have distinct markings, such as the numbat's stripes, but most do not.

GEOGRAPHIC RANGE

Animals in this order live in Australia, Tasmania, and New Guinea, and also inhabit some of the nearby Pacific islands.

HABITAT

Australasian carnivorous marsupials live in many different habitats, from the tropical rainforest to the desert. Each species has adaptations that allow it to live in its own particular environment. For example, the numbat has claws that are good for scratching at the dirt and digging out termites in the forest where it lives. The spotted-tail quoll has special ridges on the bottoms of its paws and sharp claws that help it climb large trees.

Many of the Australasian carnivorous marsupials live in habitats where it can become very hot or very cold. Different species have different ways of protecting themselves from these extreme temperatures. Some species such as the numbat dig burrows underground that they line with dead leaves and other plant parts for insulation. Other species are able to reduce their body temperatures on purpose. This is called torpor, and it reduces the amount of energy an animal needs to live when it gets too cold or is exposed to other environmental stresses, such as too little food.

DIET

Australasian carnivorous marsupials eat meat and insects. What each species eats depends on its size, habitat, and what kind of adaptations it has for hunting. Smaller species usually eat insects, and larger species eat other animals, although they sometimes eat insects as well. Many of the larger Australasian carnivorous marsupials can chew and eat whole animals, including the bones and the skin. The numbat lives in the forest and eats termites that it digs out from underground with its sharp claws or finds under the dead branches it pushes away with its pointed snout. The Tasmanian devil eats many different kinds of meat, and has been reported to eat animals as large as wallabies.

BEHAVIOR AND REPRODUCTION

Most Australasian carnivorous marsupials are nocturnal, meaning that they are only active at night. Some species, however, have shown occasional periods of daytime activity, and a few species such as the numbat are usually active only during the day.

Australasian carnivorous marsupials spend most of their time in the search for food. Each species has different ways of finding prey, from digging for termites, to climbing trees and raiding the nests of possums during the night, to feeding on the bodies of animals that are already dead.

Most Australasian carnivorous marsupials have relatively short life spans. Females usually mate with more than one male, and in many species, offspring born in the same litter have different fathers. Some species in this order only mate once during their lifetime. They usually die soon after reproducing, having used all their energy in a sudden burst of activity required to mate successfully. Antechinus (ant-uh-KINE-us), which are broad-footed marsupial mice, mate in this way. The female lives long enough to raise her young until they can live on their own, but the male often dies before his offspring are mature.

Australasian carnivorous marsupials, like all marsupials, have very short pregnancies, some lasting only days. They give birth to immature young that are usually blind and hairless, and always are unable to survive on their own. In most cases, the young make their way into the mother's pouch, which contains milk teats, and are carried with her wherever she goes. Some species have young that crawl to external teats, or nipples, of the mother. They cling there and are carried wherever the mother goes, protected only by the hairs on her underbelly. Many do not survive to maturity.

The amount of time the young spend growing outside of the mother's womb, or uterus, depends on the species. It can be as short as a few weeks or as long as many months. In most species, once the young have grown enough to fend for themselves, they spend a short amount of time in the mother's nest or den, wandering further each day to find food, until at last they leave the nest for good.

AUSTRALASIAN CARNIVOROUS MARSUPIALS AND PEOPLE

Farmers consider many Australasian carnivorous marsupials pests because they prey on livestock such as sheep and chickens. Some animals have been collected for zoos, but none of the animals in this order have been significantly hunted for their fur. In times past, some may have been hunted for food by aboriginal peoples.

CONSERVATION STATUS

Many Australasian carnivorous marsupials have not been studied by scientists. There are no good estimates of how many are left in the wild and how things such as deforestation (clearing the land of trees) are affecting them. One family in this order, Tasmanian wolves, has already gone extinct. The last time a Tasmanian wolf was confirmed to exist in the wild was in 1930. The last remaining animal was in captivity in a zoo and died shortly thereafter in 1936.

Many Australasian carnivorous marsupials such as the southern dibbler and the sandhill dunnart are considered to be Endangered, or facing a very high risk of becoming extinct in the wild. Many others are considered Vulnerable, which means they face a high risk of extinction in the wild.

WHAT'S IN A NAME?

When European settlers first came to Australia, they discovered many animals that they did not have back home. When naming the new animals, they chose names based on their experiences with how these new animals looked and sounded. One new animal had large, sharp, white teeth, and ears that turned red when it got angry. It also made horrible screeching noises in the night. The new settlers named this animal the Tasmanian devil.

There are many reasons that Australasian carnivorous marsupials are facing the threat of extinction. The cutting down of forest areas to clear land for agriculture affects many species, as does the changing pattern of fires set to clear grassland areas. Many species are Vulnerable or Endangered in Australia and surrounding areas because of the introduction of the red fox, which is not native to the region. In areas where the red fox is found, populations of Australasian carnivorous mammals have substantially decreased.

FOR MORE INFORMATION

Books:

Fenton, Julie A. Kangaroos and Other Marsupials. Chicago: World Book, 2000.

Hoare, Ben, ed. International Wildlife Encyclopedia, 3rd ed. Tarrytown, NY: Marshall Cavendish, 2002.

Nowak, Ronald M., ed. Walker's Mammals of the World, 5th ed. Baltimore and London: Johns Hopkins University Press, 1991.

Woods, Samuel G. Sorting Out Mammals: Everything You Want to Know About Marsupials, Carnivores, Herbivores, and More! Woodbridge, CT: Blackbirch Marketing, 1999.