Why do otters keep one stone for life?

| John Anderson | Nature



Sea otters have a favorite stone that they keep fanatically for life.   

Researchers found the stone is used for overcoming environmental challenges, dealing with threats, and, of course, for play – they like to roll their favorite stone very close to the chest. Another major use of stone is to break oysters for edible purposes. Yap, it’s a tool.

The otter keeps its precious stone close to its chest in a pocket of loose skin that stretches from the armpit through the chest.

Bonus Fact 1: Unlike other marine mammals, sea otters do not have a layer of fat, and instead rely on an extra-thick layer of fur for protection from the cold. Over 150,000 hairs grow on a square inch of the otter body – making otter fur the densest of all animals.

Bonus fact 2: The otter spends a lot of time grooming its fur. and its bares fruits – otters do not have lice or other parasites in their fur that create itching.