FEATHER-TAILED POSSUMS: Acrobatidae

PHYSICAL CHARACTERISTICS

The family Acrobatidae is made up of two species: the pygmy glider and the feather-tailed possum. Although they are very different in many ways, these two species have similarities that make them part of the same family.

The pygmy glider is the smaller of the two species. Their heads and bodies are usually between 2.5 and 3 inches (6.5 to 8 centimeters). They have tails that are also between 2.5 and 3 inches (6.5 to 8 centimeters) in length. The pygmy glider weighs less than 0.5 ounces (14 grams). Feather-tailed possums are larger, with a head and body length that ranges from 4 to 5 inches (10 to 13 centimeters). Their tail is longer than their body, with a length of between 5 and 6 inches (12 to 15 centimeters). They weigh between 1 and 2 ounces (30 to 60 grams).

Pygmy gliders and feather-tailed possums both have tails that are long and have long straight hairs sticking off both sides of their tail. These hairs make the tail look like a feather, which is how they got their name. Both species have large eyes and round ears. They both also have gray fur. The feather-tailed possum has black and white stripes on its face. The pygmy glider does not have these stripes and has a white belly.

Both species of this family have sharp claws that help them grip trees. They also have six pads on their feet to help them grip. The pygmy glider has a thin membrane, or piece of skin, that goes from its front legs to its back legs. This membrane allows it to glide. The feather-tailed possum does not glide and does not have this membrane.

Both species are marsupial mammals. This makes them different from most familiar mammals such as cats, dogs, and horses. These familiar mammals are all eutherian (yoo-THEER-ee-an) mammals, which means they have a well-developed placenta. A placenta is an organ that grows in the mother's uterus, womb, and lets the mother and developing baby share food and oxygen. Marsupial mammals do not have this type of placenta. Because of this, they give birth to young that are not physically developed enough to be able to survive on their own. Instead, the young are carried around either in a pouch or attached to the mother's teats, or nipples, on her underside until they have developed more fully and can survive on their own.

GEOGRAPHIC RANGE

The pygmy glider lives in eastern Australia. The feather-tailed possum lives in New Guinea.

HABITAT

Both species in this family live in trees. Feather-tailed possums live in tropical rainforests and woodland areas. They are also sometimes found in suburban gardens. Pygmy gliders prefer forests that contain many eucalyptus (yoo-kah-LIP-tus) trees. They also live in other woodland areas.

DIET

Pygmy gliders and feather-tailed possums eat insects, fruit, flowers, and nectar.

WHAT MAKES A FAMILY?

Pygmy gliders and feather-tailed possums are in the same family, but they are different in many ways. Pygmy gliders have a special membrane that allows them to glide, while feather-tailed possums do not. Scientists look at many different clues to decide what species are similar enough to belong in the same family. These possums have ears that are very complex and unique to these two species. This is the kind of information scientists used to decide that these two species belonged in the same family, even though they may not look very similar.

BEHAVIOR AND REPRODUCTION

Both the pygmy glider and the feather-tailed possum are nocturnal, which means they are active mainly at night. They have flexible prehensile tails that allow them to grab hold of branches. Feather-tailed possums usually live alone or in pairs, but pygmy gliders often live in groups and make nests out of dry leaves in branches or hollows in trees.

Feather-tailed possums have one or two offspring at a time, while pygmy gliders usually have three or four offspring. They both give birth to young that are underdeveloped and spend time in the pouch while they grow and mature. After they leave the pouch, the young spend time in the nest before being weaned, no longer dependent on their mother's milk, and are ready to fend for themselves.

FEATHER-TAILED POSSUMS AND PEOPLE

Feather-tailed possums do not have any known significance to humans except to the scientists who study them.

CONSERVATION STATUS

Neither species of feather-tailed possum is considered threatened. They do not face a high risk of extinction in the wild in the near future.

PYGMY GLIDER (Acrobates pygmaeus): SPECIES ACCOUNT

Physical characteristics: The pygmy glider is the smalles marsupial that is able to glide. They weigh less than 0.5 ounces (14 grams)> Their head and body measure between 2.5 and 3 inches (6.5 to 8 centimeters) in length. Their tail is also usually about 2.5 to 3 inches (6.5 to 8 centimeters) long. Females have pouches that contain four nipples.

Pygmy gliders have fur that is soft and gray. Around their large eyes are circles of black fur. Their belly is white. The pygmy glider's tail is about as long as its body and has long stiff hairs on each side of it. A membrane with fur on it is attached to either side of the pygmy glider's body from its front feet to its back feet.

Geographic range: Pygmy gliders are found in eastern Australia.

Habitat: Pygmy gliders live in forest areas where there are many

eucalyptus trees. They also live in woodland areas.

Diet: Pygmy gliders eat mainly insects. They also eat nectar

from flowers.

Behavior and reproduction: Pygmy gliders are nocturnal. They live in trees and rarely spend any time on the forest floor, where they would be vulnerable to predators. Pygmy gliders are very social animals. They build nests out of leaves in branches and holes in trees. Many pygmy gliders live together in one nest. When it gets cold, they often huddle together to share warmth. When it gets especially cold or there is not enough food, pygmy gliders can go into torpor. Torpor is when the animal purposely lowers its body temperature and heart rate temporarily to conserve energy, similar to hibernation.

Pygmy gliders glide by jumping and then spreading their hands and feet so that their special membrane becomes stretched out. This membrane acts like a parachute so that the pygmy glider glides instead of falling. The feather-like tail is used to help control the glide. This way they are able to glide distances of up to 65 feet (20 meters) or more at a time. Because they live in trees and almost never go down to ground level, gliding is an important way for this species to move from tree to tree.

Pygmy gliders usually have three or four offspring at a time. The mother gives birth to young that are not able to fend for themselves. The young crawl into her pouch where they continue to grow. Once the young have fur and are a little older, they sometimes ride around on their mother's back. After about sixty days, they leave the pouch and stay in the nest alone. They stay in the nest for another thirty-five or forty days. At this time the young are weaned, although they might not leave the nest. The day that the babies are born, the mother mates and gets pregnant again. The new fetuses stop developing until just before the young have been weaned. This means that the mother gives birth again just a day or two after the last set of young has stopped nursing.

Pygmy gliders and people: Pygmy gliders are not known to have special significance to people except to the scientists who study them.

Conservation status: Pygmy gliders are not considered threatened. They are not at risk of extinction in the wild in the foreseeable future. ∎

FOR MORE INFORMATION

Books:

Smith, Andrew, and John Winter. A Key and Field Guide to the Australian Possums, Gliders and Koala. Chipping Norton, Australia: Surrey Beatty and Sons, 1997.

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

Web sites:

Australian National Parks and Wildlife. "Gliding possums." http://www.nationalparks.nsw.gov.au/npws.nsf/Content/Gliding+possums (accessed on June 30, 2004).