<P> 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 . </P> <P> 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 35 species of Australian freshwater turtles from eight genera of the 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 . </P> <P> 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 . </P> <P> There are more than 700 species of lizards in Australia with representatives of five families . There are over 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 about 450 species of skink from more than 40 genera, comprising more than 50% of the total Australian lizard fauna; this group includes the blue - tongued lizards . </P>

Although most species of non domestic mammals in australia