A deadly predator, learn about saltwater crocodiles in our expert guide, including where they live in the wild, diet and whether crocodiles really sleep with one eye open.
How big do saltwater crocodiles get?
Saltwater crocodiles (Crocodylus porosus), aka ‘salties’ or estuarine crocodiles, are enormous creatures and the world’s largest living reptiles. The average male is 5m in length and weighs around 500kg, while females are significantly smaller, with the average female saltwater crocodile measuring a little under 3m in length and weighing less than 100kg.
What’s the biggest saltwater crocodile ever found?
The largest saltwater crocodile ever recorded was around 6.3m long, but individuals of up to 7m have probably lived in the past. It’s possible that such large crocodiles no longer exist due to extensive hunting of the largest specimens. These huge male salties are estimated to have weighed a staggering 1500-2000kg.
The short answer is yes. “Most crocodiles can achieve 12–14kph for short periods,” says crocodile specialist Adam Britton, “which is slower than a fit human can run. So if you’re in reasonable shape, you could definitely outrun a croc.”
Crocodiles have three main types of locomotion: the belly-crawl, used over mud; the high walk, in which the legs push the body up off the ground; and the ‘gallop’, where they bound like a rabbit. “Ancient croc-like creatures likely galloped after prey on land, but most modern crocodiles only gallop to escape danger,” says Adam, “taking prey by surprise launches from the water.”
Saltwater crocodiles have a huge range that extends from northern Australia to eastern India and South-east Asia. As their name suggests, saltwater crocodiles are able to live in coastal habitats, but they are comfortable in freshwater rivers as well.
These huge reptiles are so well adapted to life in saltwater that they are able to spend days or even weeks at sea, drifting and swimming hundreds of kilometres and possibly hunting en route.
Saltwater crocodiles have long lifespans, with many living to more than 65 years, longer than any other crocodile species. It’s possible that some saltwater crocodiles may live for over a century, but this has never been verified in the wild. In captivity, there have been several reports of crocodiles living to be over 100 years old.
On the flip side, infant mortality is extremely high in saltwater crocodiles due to extensive predation, and only 1% of newborn salties will survive to adulthood.
Do crocodiles really sleep with one eye open?
Australian legend has it that crocodiles sleep with one eye open – and scientists have now proved it to be true.
Australian saltwater crocodiles join several aquatic mammals and birds in being capable of unihemispheric sleep, which involves shutting down only one half of their brain at a time, keeping the other half alert to danger.
The central nervous system is wired up such that the right eye remains open when the left side of the brain is awake, and vice versa.
Disconcertingly, experiments showed that the crocodiles were particularly likely to keep an eye out when humans, rather than other crocodiles, were nearby.
They typically feed on fish, mammals and birds, preferring to hunt at night. Even small crocodiles are able to take relatively large prey, and nothing really stands a chance against a large male saltwater crocodile, which is capable of killing and eating pretty much anything that comes into its territory, including sharks and humans.
What’s the “death roll”?
Salties are known for the ‘death roll’ – a hunting behaviour reserved for larger prey. After drowning its victim, the crocodile rapidly rolls it in the water in order to remove its limbs, as its teeth are designed for gripping rather than tearing flesh.
What would you do if you were attacked by a crocodile? How would you escape? Discover one man’s incredible story about literally escaping from the jaws of a crocodile: