Australia's Strangest Animals

Australia's Strangest Animals

Australia's animals are among nature's oddest creations. So weird are the creatures that hop, burrow, slither, and amble across the Australian landmass that, until the 20th century, it was believed that the continent's fauna had a different evolutionary starting point from the rest of the Earth's species.

Australia's animal life was shaped by its plants, and they, in turn, were determined by the climate, which dramatically changed around 15 million years ago. Moist, rain-bearing winds that once irrigated the heart of the continent died, the great inland sea dried up, and the inland rain forests vanished -- flamingos and freshwater dolphins along with them.

The animals that did survive have evolved in strange and fascinating ways. For example, during droughts the water-holding frog locks itself away in an underground chamber, where it remains in a state of suspended animation waiting for rain for up to seven years. The ferocious looking thorny devil uses its heavy armor to collect water. Its exaggerated spikes and spines give the creature an enormous surface area. Dew condenses on the spines and is then channeled into its mouth.

The kangaroo is a superb example of adaptation. In the parched semidesert that covers most of central Australia, kangaroos must forage for food over a wide area. Their powerful hind legs act as springs, enabling them to travel long distances while using relatively little energy.

Kangaroos, wallabies, and their midsize relations vary enormously in size, habitat, and location. Australia has everything from rat-size specimens to 6-foot, 200-pound red kangaroos from the cool, misty forests of Tasmania to the northern tip of Cape York.

One of the most fascinating groups of Australian animals is the monotremes, who lay eggs, as reptiles do, but are warm-blooded and suckle their young with milk. Only three species of monotremes survive: the platypus, a reclusive crustacean-eater found in freshwater streams in eastern Australia, and two species of echidna, a small, spiny termite-eater.

Best loved of all Australia's animals is the koala. A tree-dwelling herbivore, the koala eats a diet entirely of eucalyptus leaves, which are low in nutrients and high in toxins. As a result, koalas must restrict their energy level. Typically, a koala will spend about 20 hours of each day dozing in a tree fork. Even the koala's brain has adapted to its harsh regimen. A human brain uses about 17% of the body's energy, but the koala saves on the wasteful expenditure by starting out with a brain the size of a small walnut.

However deficient in the cerebellum it may be, though, one thing that the koala will not tolerate is being called a bear. Cute and cuddly as it is -- and despite its resemblance to every child's favorite bedmate -- the koala is a marsupial, not a bear.