Do animals have a natural instinct that tells them saltwater is bad, that they can’t drink it?
It seems that a thirsty animal, especially one that didn’t grow up near a beach, would gulp down seawater without a second thought. Sure, it would taste like hell, but animals drink all kinds of fresh water from ditches and such that must taste terrible as well.
I’d guess the saltiness would make them not want to drink it – it tastes bad to them.
Though some animals – seagulls, for instance – can drink salt water with not ill effect. They tend to have a way of expelling the salt.
I had an Airdale Terrier named Red. Took him and another dog, Speedway, to a park located on Puget Sound. Both ran to the water and neither hesitated to jump right in. Red lapped at the water 3 times before he realized that it did not taste so good. He shook his head and ran up and looked at me like I had played a trick on him. Good thing he knew how to drink out of a drinking fountain. Speedway was smart enough to sniff the water to see if it was drinkable. Airdales are not the smartest dogs around and this was one of the many ways Red proved it.
I’m not sure the taste is what makes them not drink the water. Deer and cows often are given salt licks. Any other animals? Perhaps it’s the smell?
It’s evolutionary selection. Those animals which could not differentiate appropriate drinking water from inappropriate by the taste tended to not pass on their genes.