Meet the Saltwater crocodile
Large males can top six metres and a tonne, making the saltie the world's largest living reptile. The largest reliably measured Australian specimen was at least 6.15 m, caught in the Mary River, Northern Territory, in 1974.
Despite the name, salties are just as happy in freshwater billabongs and rivers as in the sea, and they turn up on islands far offshore. They are ambush hunters: young crocs eat crabs, prawns and insects, while big adults take fish, birds, turtles, wallabies and even buffalo.
Females build mounds of vegetation and mud on riverbanks during the wet season and lay up to about 70 eggs. The temperature inside the nest decides each hatchling's sex, and the mother guards the nest and helps the hatchlings to water.
Between the 1940s and 1960s, hunting for skins and sport drove salties close to extinction in parts of northern Australia. Protection came in the early 1970s, and numbers have since recovered strongly, which is why crocodile safety signs are now everywhere in the Top End.
Where it lives
Coastal northern Australia from around Broome in Western Australia, across the Top End, to about Gladstone in Queensland, and overseas through South-East Asia to India and the Solomon Islands. It lives in tidal rivers, estuaries, mangroves, floodplain billabongs and the sea, and can turn up far inland and on islands well offshore.