Plants and Animals, Animals
Queensland lungfish, phalangers, Mesozoic times, ringtail possum, mutton birds
A large proportion of Australia’s native animal species exist nowhere else in the world. Of Australia’s animal species, it is estimated that 84 percent of mammals, 89 percent of reptiles, 93 percent of frogs, and 45 percent of birds are endemic. Some archaic species, such as the Queensland lungfish, have changed little since Paleozoic or Mesozoic times. Scientists estimate that 19 land mammals and 20 birds have become extinct (that is, not sighted in the wild for at least 50 years) since European settlement. The World Conservation Monitoring Centre classifies 58 mammals, 45 birds, 37 reptiles, and 25 amphibians as threatened.
One striking aspect of the native mammal life in Australia is the absence of representatives of most of the orders found on other continents. In contrast to other continents, Australia has a preponderance of marsupials (mammals that raise their young in a marsupium, or abdominal pouch), with some 144 original species (10 became extinct after 1788). Australia is also noted for its comparatively abundant presence of monotremes, which are egg-laying mammals. Only two types of monotremes native to Australia are known to survive. The platypus, a zoological curiosity, is a semiaquatic, furred mammal with an elongated snout resembling a duck bill; the legs of the adult male platypus are equipped with poisonous bony spurs for defense. The platypus is found in eastern and southern Australia, including Tasmania. The other monotreme is the spiny anteater, or echidna, which is found throughout Australia as well as New Guinea.
The best-known marsupials of Australia are the kangaroos, which include about 50 species. Kangaroos are herbivores. They dwell in many areas of the country, and some have become so accustomed to humans they can be considered tame. The large red or gray kangaroo may stand as high as 2 m (7 ft) and can leap up to 9 m (30 ft). The wallaby and kangaroo rat are smaller members of the kangaroo family. The phalangers are herbivorous marsupials that live in trees, including the ringtail possum. The koala, also a tree-dwelling marsupial, is found in the wild only in the eucalyptus forests of eastern Australia. Other well-known marsupials are the burrowing wombat, bandicoot, and pouched mouse. The carnivorous Tasmanian devil, principally a scavenger, is found only on the island of Tasmania.
Rodents, bats, and the dingo belong to a different order of mammals. Scientists believe they were the earliest significant nonnative species, arriving from the Asian mainland and the string of islands to the north of Australia thousands of years ago. While rodents and bats migrated on their own, the doglike dingo was perhaps the first species to be introduced by humans. It is believed that dingos were introduced into Australia about 4,000 years ago by seafarers from Southeast Asia and the Indonesian islands.
When Europeans settled in Australia, they brought many species of animals with them. Many of these originally domesticated animals have established large feral (wild) populations, including horses (locally known as brumbies), cattle, cats, camels, deer, dogs, donkeys, goats, pigs, rabbits, and water buffalo. These animals have spread throughout the country, most notably in the sparsely populated outback, causing serious ecological and economic damage. The most widespread damage has been caused by the European rabbit, which was brought to Australia in the mid-19th century mainly for sport. These rabbits quickly reached plague proportions on the continent, where they had no natural predators, and their total population reached as many as 500 million. The damage they cause includes soil erosion, the destruction of habitat for native species, and large agricultural losses. Rabbits, as well as foxes and feral cats, have been repeatedly targeted for massive national efforts in biological control and regional eradication programs.
Another introduced species, the South American cane toad, was imported in 1935 from Hawaii into Queensland’s sugarcane country in the hope of controlling beetles and other insect pests. However, it became a grotesquely successful pest in its own right. In the absence of serious predators, the toad has infested much of the state and is migrating into the northern tropics.
Australia’s indigenous amphibians are modest in number due to the prevailingly dry climate. However, some have developed ways to survive the harsh climate of the Australian outback. The burrowing bullfrog, for example, emerges from its underground home to feed and mate only during the brief, infrequent rains.
Australia contains a wide variety of reptile life. In fact, a majority of the land vertebrates are in this class. There are more than 500 species of lizards, including the gecko, skink, and the giant goanna. About 100 species of venomous snakes are found in Australia. The taipan of the far north, the death adder, the tiger snake of the south, the copperhead, and the black snake are the best known of the poisonous snakes. Australia also has two species of freshwater crocodiles. The larger of these, found in the estuaries and coastal swamps along the northern coast, attains lengths of 6 m (20 ft).
The waters surrounding Australia support a wide variety of fish and aquatic mammals. Several species of whales populate southern waters, and seals inhabit parts of the southern coast, the islands in Bass Strait, and Tasmania. Dugong, trepang (sea cucumber), trochus, and pearl shell are found in northern waters. Edible fish and shellfish are abundant, and the oyster, abalone, and crayfish of the warmer southern waters have been exploited commercially. Australian waters contain some 70 species of shark, several of which are dangerous to humans. The Queensland lungfish, sometimes called a living fossil, breathes with its single lung when low river levels render its gills ineffective. Australia has about 3,000 species of marine and freshwater fish. Introduced species, most conspicuously the European carp, threaten the survival of many native species.
Most insect types are represented in Australia, including flies, beetles, butterflies, bees, mosquitoes, and ants. Several of the 260 or so types of mosquitoes are responsible for the transmission of disease to animals and humans in the country’s tropical and temperate regions. The giant termites of northern Australia build huge, hill-like nests up to 6 m (20 ft) in height. Australia has earthworms in abundance, including the giant earthworms of Victoria, which range from 0.9 to 3.7 m (3 to 12 ft) in length, reportedly the longest in the world.
Australia is the home of 751 known species of birds, ranging from archaic types, such as the giant, flightless emu and cassowary, to highly developed species. The fan-tailed lyrebird has great powers of mimicry. The male bowerbirds build intricate and decorative playgrounds to attract females. The largest species of kookaburra has a raucous call for which it is nicknamed the “laughing jackass.” Many varieties of cockatoos and parrots are found; the budgerigar is a favorite of bird fanciers. The white cockatoo, a clever mimic, is more common than the black cockatoo. Black swans, spoonbills, herons, and ducks frequent inland waters. Smaller birds include wrens, finches, titmice, larks, and swallows. Gulls, terns, gannets, mutton birds, albatrosses, and penguins are the most common seabirds. The mutton bird, found mainly on the islands of Bass Strait, is valued for its edible flesh.
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