What is the largest reptile in the world?

The saltwater crocodile, reaching six metres and over a tonne. It has the strongest measured bite of any living animal, around 16,000 newtons, and almost no muscle for opening its jaws - which is why a band of tape round a crocodile's snout is enough to hold it shut, a fact that looks absurd and is genuinely how they are handled.

Despite the name it is not confined to salt water; it lives in rivers and estuaries across northern Australia and Southeast Asia and simply tolerates the sea better than other crocodilians, which lets it cross open ocean. Tracking has shown individuals travelling hundreds of kilometres by riding tidal currents - waiting for the flow to turn in their favour and going with it, rather than swimming.

They are also considerably more sophisticated than the log-with-teeth reputation. Crocodiles have a four-chambered heart, care for their young by carrying hatchlings to water in their jaws and guarding them for months, hunt cooperatively, and have been recorded balancing sticks on their snouts during nesting season where birds are collecting nest material. Their closest living relatives are birds, not lizards.