Fauna of Australia - Amphibians and Reptiles

Amphibians and Reptiles

Australia has four families of native frogs and one introduced toad, the Cane Toad. In 1935 the Cane Toad was introduced to Australia in a failed attempt to control pests in sugarcane crops. It has since become a devastating pest, spreading across northern Australia. As well as competing with native insectivores for food, the Cane Toad produces a venom that is toxic to native fauna, as well as to humans. The Myobatrachidae, or southern frogs, are Australia's largest group of frogs, with 112 species classified into anywhere from 17 to 22 genera. A notable member of this group is the colourful and endangered Corroboree Frog. The tree frogs, from family Hylidae, are common in high rainfall areas on the north and east coasts; there are 77 Australian species from three genera. The 18 species from two genera of the Microhylidae frogs are restricted to the rainforests of northern Australia and nearby habitats; the smallest species, the Scanty Frog, is from this family. There is a single species from the world's dominant frog group, family Ranidae — the Australian Wood Frog — which only occurs in the Queensland rainforests. As elsewhere, there has been a precipitous decline in Australia's frog populations in recent years. Although the full reasons for the decline are uncertain, it can be at least partly attributed to the fatal amphibian fungal disease chytridiomycosis. Another theory for the decline might be, as research shows, that species from the Southern Hemisphere are on average 4.6 million years old, compared to an average 2.9 million years old for the Northern Hemisphere: Researchers believe this age difference is because of the history of severe Ice Ages in the Northern Hemisphere, which may drive older species to extinction.

Australia has two species of crocodile. The Saltwater Crocodile, known colloquially as the "salty," is the largest living crocodile species; reaching over 7 m, and weighing over 1,000 kg, they can and do kill people. They live on the coast and in the freshwater rivers and wetlands of northern Australia, and they are farmed for their meat and leather. Freshwater Crocodiles, found only in northern Australia, are not considered dangerous to humans.

The Australian coast is visited by six species of sea turtle: the Flatback, Green Sea, Hawksbill, Olive Ridley, Loggerhead and the Leatherback Sea Turtles; all are protected in Australian waters. There are 29 species of Australian freshwater turtles from eight genera of family Chelidae. The Pig-nosed Turtle is the only Australian turtle not of that family. Australia is the only continent without any living species of land tortoise.

Australia is the only continent where venomous snakes outnumber their non-venomous cousins. Australian snakes belong to seven families. Of these, the most venomous species, including the Fierce Snake, Eastern Brown Snake, Taipan and Eastern Tiger Snake are from the family Elapidae. Of the 200 species of elapid, 86 are found only in Australia. Thirty-three sea snakes from family Hydrophiidae inhabit Australia's northern waters; many are extremely venomous. Two species of sea snake from the Acrochordidae also occur in Australian waters. Australia has only 11 species from the world's most significant snake family Colubridae; none are endemic, and they are considered to be relatively recent arrivals from Asia. There are 15 python species and 31 species of insectivorous blind snake.

There are more than 700 species of lizards in Australia with representatives of five families. There are >130 species in 20 genera of gecko found throughout the Australian continent. The Pygopodidae is a family of limbless lizards endemic to the Australian region; all 39 species from seven genera occur in Australia. The Agamidae or Dragon lizards are represented by 70 species in 14 genera, including the Thorny Devil, Bearded Dragon and Frill-necked Lizard. There are 30 species of monitor lizard, family Varanidae, in Australia, where they are commonly known as goannas. The largest Australian monitor is the Perentie, which can reach up to 2 m in length. There are 389 species of skink from 38 genera, comprising about 50% of the total Australian lizard fauna; this group includes the blue-tongued lizards.