Crocs sweat salt from their tongues

Why don't saltwater crocodiles shrivel up like raisins after drinking from the ocean? They have modified salivary glands on their tongues that act like biological desalination plants.

These lingual salt glands pump concentrated salt out of the body at a rate far higher than any kidney could manage. While a human would die of dehydration trying to process seawater, the crocodile simply secretes a thick, salty fluid through its tongue and spits it out.

This system is so efficient that a crocodile can spend months at sea without ever touching fresh water. They aren't actually crying when they crawl onto land; while they have salt glands on their tongues, the 'tears' seen near their eyes come from separate lachrymal glands that also help excrete excess salt.

Oddly, some species of crocodiles have these glands even though they live exclusively in freshwater rivers. This suggests their ancestors were ocean voyagers who never bothered to lose their offshore survival gear.