Crocodile – Australian Wildlife
The saltwater crocodile (Crocodylus porosus), also known as the estuarine crocodile, Indo-Pacific crocodiles, marine crocodiles, sea crocodile or informally as saltie, is the largest of all living reptiles, as well as the largest riparian predator in the world. Males of this species can reach sizes up to at least 6.30 m (20.7 ft) and possibly up to 7.0 m (23.0 ft) in length. However, an adult male saltwater crocodile rarely reaches or exceeds a size of 6 m (19.7 ft) weighing 1,000 to 1,200 kg (2,200–2,600 lb). Females are much smaller and often do not surpass 3 m (9.8 ft).
As its name implies, this species of crocodile can live in marine environments, but usually resides in saline and brackish mangrove swamps, estuaries, deltas, lagoons, and lower stretches of rivers. They have the broadest distribution of any modern crocodile, ranging from the eastern coast of India throughout most of Southeast Asia and northern Australia.
The saltwater crocodile is a formidable and opportunistic hypercarnivorous apex predator. Most prey are ambushed and then drowned or swallowed whole. It is capable of prevailing over almost any animal that enters its territory, including other apex predators such as sharks, varieties of freshwater and marine fish including pelagic species, invertebrates such as crustaceans, various reptiles, birds and mammals, including humans. Due to their size, aggression and distribution, saltwater crocodiles are regarded as the most dangerous extant crocodilian to humans.
Crocodylus porosus is believed to have a direct link to similar crocodilians that inhabited the shorelines of the supercontinent Gondwana (which included what is now the Australian continent) as long ago as 98 million years and were survivors of the Cretaceous–Paleogene extinction event. Fossils of Isisfordia discovered in outback western Queensland (once a vast inland sea), though smaller in size, show attributes of direct lineage to Crocodylus porosus, suggesting it occupied a similar habitat, with vertebrae indicating it shared the ability to death roll during feeding. Incomplete fossil records make it difficult to accurately trace the emergence of the species. The genome was fully sequenced in 2007. The earliest fossil evidence of the species dates to around 4.0–4.5 million years ago and no subspecies are known. Scientists estimate that C. porosus is an ancient species that could have diverged from 12 to 6 million years ago. Genetic research has unsurprisingly indicated that the saltwater crocodile is related relatively closely to other living species of Asian crocodile, although some ambiguity exists over what assemblage it could be considered part of based on variable genetic results. Other relatively broad-snouted species such as Mugger (C. palustris) and Siamese crocodiles (C. siamensis) seem to be the most likely candidates to bear the closest relation among living species.