Sea Otters Have Been Using Tools for Millions of Years

Sea otters are expert tool users, using rocks to expertly break open shellfish to extract the nutritious, fleshy insides. And it looks like they’ve been honing their skills for a long time, long before other marine mammals—even dolphins—picked up their own tools.

A genetic study of more than 100 wild sea otters living off the coast of California suggests that their ancestors living millions of years ago were similarly adept. The study was published in the journal Biology Letters by a group of researchers from the Smithsonian Conservation Biology Institute.

If sea otters’ ancestors held rocks on their chests, then that may explain the depressions found in the chests of some modern otters. Researchers plan to study fossil remains to confirm when the behavior may have started.

A genetic study suggests sea otters’ ancestors also used tools millions of years ago.

This behavior seems innate in all young sea otters, according to the researchers. In their paper, they wrote: “Orphaned otter pups raised in captivity exhibit rudimentary pounding behaviour without training or previous experience, and wild pups develop tool-use behaviour before weaning regardless of their mother’s diet type.”

Sea otters appear to be a unique case of what seems to be intrinsic tool use. Here’s Helen Briggs reporting for BBC News:

“Sea otters provide a fascinating opportunity to investigate how genetic predispositions, learning, and environmental conditions contribute to a species’ capacity to use foraging tools,” said Dr Christian Rutz, an evolutionary ecologist at the University of St Andrews, who studies tool use in Hawaiian crows and New Caledonian crows.

Tool use is certainly not exclusive to sea otters. Scientists have observed a wide range of animals—including dolphins, primates, and crows—using tools.

Researchers have observed dolphins off the coast of Australia use sponges when looking for fish on the sea floor, the idea being that the sponges protect their nose. But that behavior is relatively new, dating back to less than 200 years ago. Other researchers have studied how crows bend twigs into hooks to extract food hidden in wooden logs.