The saltwater crocodile hatches at 71 grams and can end up past a tonne
A newly hatched saltwater crocodile is about 28 cm long and weighs roughly 71 grams, less than a chocolate bar. A big male can grow past 6 metres and 1,000 kg, making this species the largest reptile alive. Few animals on Earth change size so dramatically over one lifetime.
Salties range from India's east coast through Southeast Asia to northern Australia and Micronesia, living in mangrove swamps, river deltas and freshwater rivers as well as the sea. They are ambush hunters that drown their prey or swallow it whole, and they will take almost anything that strays into their territory, sharks included. Hunting for their skins was widespread until the 1970s, yet the species has been rated Least Concern since 1996, though it is locally extinct in Cambodia, China, Thailand, Vietnam and the Seychelles.
Physics explains part of the drama in their size. Weight rises roughly with the cube of length, so a 6 m crocodile weighs more than twice as much as a 5 m one, and older animals stop lengthening much and simply bulk up. A large male's head alone, with its muscles, can exceed 200 kg. The biggest one ever confirmed became tangled in a net and drowned in 1979 in Papua New Guinea; its dried skin and head measured 6.2 m, suggesting about 6.3 m in life.
No other crocodilian shows such a gap between the sexes. Adult females usually measure 2.7 to 3.1 m and weigh around 76 to 103 kg, while males average four to five times heavier and can be twice as long. Their bodies are also unusually broad for a crocodile, which led early observers to wonder whether they were alligators. Juveniles are pale yellow with black stripes and spots, darkening over several years to a greenish drab.
Scientists once named several separate species from specimens that turned out to be salties, including a supposed Australian species in 1985 that was really just an old, heavy male. Today it is treated as a single species. Genetic work suggests its genus arose in Africa and split from an extinct Madagascar relative about 25 million years ago.
Source: Saltwater crocodile
