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    Australia

Australia

Australia is the only place on earth where you’ll find koalas and kangaroos, and this section of the museum highlights how those species have adapted to their environment.

How did kangaroos get to Australia to begin with? More than 100 million years ago, the Australian land mass was connected to Asia. Fossils from around that time show that monotremes, egg-laying mammals like the platypus, were present in what would become Australia, as well as marsupials, mammals with a pouch, like kangaroos.

Over time, the forces of continental drift pushed Australia into isolation in the South Pacific Ocean. That isolation meant that the monotremes and marsupials had little competition from placental mammals and few natural predators for millions of years.

Over the last 20 million years the Australian climate changed from mostly rainforest, to woodlands, grasslands, and desert, with only a tiny amount of rainforest. Two kangaroos displayed here show how those species have adapted to that changing landscape: the Red kangaroo, which can reach 5 feet in height, can hop long distances across the grasslands with a heavy tail for balance, long back feet for pushing off from the ground, and powerful back legs. In contrast, the much smaller tree kangaroo is built for climbing and living in trees, with all four legs of about the same length, smaller, flexible feet which curve around branches, and curved claws to help their grip.

An adult kangaroo has few natural predators. One of the largest, shown here, is the Australian dingo, which appeared in Australia fewer than 4,000 years ago. A display here illustrates how dingoes hunt in packs, and how that cooperative hunting style helped them survive against Australia’s only other big predator, the thylacine.

The other interesting display in this area is on the monotremes, which include the platypus and echidna, and are found only in Australia and New Guinea. The echidna looks like the tiny result of a wild night between a porcupine and an anteater – they’re adorable, and there should be a cartoon character based on one.

South America Next on the tour is South America, just down the side hall from Australia. More mammals live in South America than anywhere else on earth. These exhibits focus on the animals that live in the rainforest canopy and how they get their food. Animals featured include the Southern squirrel monkey, which hops between trees looking for fruit and insects; the Jamaican fruit-eating bat; and the pygmy marmoset, the world’s smallest monkey. Because of its size, the marmoset has developed a set of teeth that dig into trees like tiny saws, allowing the tree’s sap to flow. The tree sap provides an important source of calories for the marmoset, which supplements its diet with small insects.

Also living in the tree branches is the three-toed sloth. What’s interesting about the sloth is that it eats only tree leaves, and hasn’t expanded its diet to include insects, fruit, or tree sap. The display notes that to cope with this low-calorie lifestyle, sloths conserve energy by being among the slowest-moving of all mammals.

The last section of the South American mammals focuses on the adaptations of those that live on the forest floor, from the long tongues of the anteater to the grass-cutting teeth of the capybara.

North America When finished with South America, head across the hall to the exhibit on North America’s mammals. North America’s climate and landscape vary tremendously, from rainforests to tundra, and from very warm to very cold. The mammals shown here demonstrate the ability to adapt to these different conditions. The museum separates the cold-weather mammals from the rest of the displays, to focus on those animals’ ability to stay warm and find food through the winters.

Adaptations on display here include different hibernation strategies, from naps of a few hours to a few months; “goose bumps” – small-muscle contractions that cause body hair to stand on end and trap air close to the surface; shivering, which rapidly contracts and relaxes muscles to generate heat; blubber, which keeps marine mammals warm in cold water, eating frequently to boost metabolism; and huddling together for warmth, which reduces an individual’s surface area exposed to cold air. Animals shown include the everything from small red squirrels, to Canada lynx, to polar bears.

Two detailed displays in this section show how larger mammals have adapted to the cold. In one, the caribou have adapted cool, long legs and hooves near the snow, with a warm upper body that protects its vital organs. In addition, the caribou’s hair traps warm air close to its body. To find food, the caribou migrate more than 600 miles from their summer homes during winter.

Also shown are two North American bear species: the brown bear, North America’s largest living carnivore, and the polar bear. These bears’ paws are compared in this display, showing how the brown bear’s paw has evolved to live on land while the polar bear’s paw has adapted to life in cold water and on ice.

Unofficial Tip: If you have children, point out the similarities in body types between animals from Africa’s savannas and North America’s prairies.

The remainder of North America’s exhibits covers the prairies and forests. Because the prairies are, like Africa’s savannas, wide-open expanses of land in which animals can’t hide from predators, you’ll see animals here have developed characteristics similar to those in Africa. In particular, the bison and pronghorn antelope have long legs to help them run fast. They also tend to live in herds for safety.

Remember the African fennecs that burrow underground to stay cool during the hottest part of the day? In North America, the black-tailed prairie dog and black-footed ferret shown here do the same thing, for the same reason.

The last part of the North America section is Spring Forest, with animals that will be familiar to most families living in the eastern United States and Canada: cottontail rabbits, white tailed deer, squirrels, opossums, mice, and weasels).

The displays here focus on how these animals create and raise their young. One of the more interesting illustrations is a comparison of the reproductive strategies of the deer and deer mouse. In a typical 12-month cycle, a female deer will give birth to 1 or 2 fawns in the spring, and spend the rest of the year raising them. The low number of children, the attention given by the mother, and relatively few predators (especially in the eastern U.S.) means the mortality rate for deer is relatively low, and the chances are good that the fawns will survive long enough to have their own children.

Contrast that with the high mortality rate of the deer mouse, whose offspring are eaten by everything from snakes and owls, to wolves and outdoor house cats. Because they have a substantially higher mortality rate, deer mice have evolved to give birth several times per year, to large litters of young. In fact, a deer mouse can reproduce four times as often as a deer, with the mouse’s offspring able to give birth before a deer’s fawns have even left their mother.

Other Lands at Smithsonian National Museum of Natural History

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