Sea otters turn to rocks and trash in fight for survival

AUSTIN (KXAN) -- Sea otters are on the edge of extinction. There are currently around 3,000 of them living off the coast of California's Monterey Bay, according to Brett Long with the Aquarium of the Pacific in Long Beach, California.

New research from biologists currently with the University of Texas at Austin is shedding light on how these furry, cuddly creatures may survive.

"Monterey Bay is just full of them. So I said, why not? Who doesn't want to work with a fuzzy teddy bear like animals?" said Chris Law, a postdoctoral researcher currently at UT Austin. Law began his research while attending the University of California at Santa Cruz.

There are 13 species of otter, with southern sea otters being one of the largest. "They are one of the few tool users in the animal kingdom," Law said. One species of river otter lives in Texas.

Tools and survival

This ability to use tools could save their species. Hunters and fur traders once nearly wiped out the species. In the 1920s, the species was on the brink of extinction, with many assuming they had been wiped out until the 1930s.

Efforts to save the species brought them back from just 50 sea otters to the 3,000 we have today. Now, food scarcity is the biggest threat.

"Urchins and abalone are both declining in populations, most likely due to just sea otters eating on them. So they're forced to switch to alternative prey," Law said.

Here is where the tools come in. The alternate prey includes clams and other hard shell creatures. Getting to the meat within the shells is challenging. "It takes a mound of effort to break them open," Law said.

So otters have turned to tools. "They'll use rocks, or even other shells, even trash like bottles and, or things and even like people's boats or docks, and they'll treat it as an anvil."

Law said that this behavior is essential to their survival. Without access to these hard shell food sources, they could die off. Without tools, they wouldn't be able to access these meats easily.

Taking a bite out of survival

Another advantage to using tools: tooth health. New research published by Law in the scientific journal Science shows the impact tool use has on sea otter teeth.

"We were curious to see if individuals that use tools more frequently, are they actually showing a reduction in tooth damage," Law said.

Southern sea otters have flat teeth. "In order to break into them, they typically use their teeth, which have these more layer formed dentition. So very flat teeth similar to ours, they're perfect for crushing."

The researchers found that the sea otters that used the tools had better, healthier teeth. "We found that there is a pretty cool pattern between that in which individuals that use tools frequently actually do show reduce overall to damage compared to those non tool users," Law said.

Researchers gathered their data from a few sources. Many researchers, including people from the US Geological Survey, Fish and Wildlife, the Monterey Bay Aquarium and UC Santa Cruz, study sea otters in Monterey Bay, gathering data on their teeth during their work. Dead otters that washed up on shore were also dissected.

Female sea otters were the most prominent tool users.

"They are the ones that primarily raising the pups. So it's super energetically costly to raise both pups and themselves in that cold Pacific environment." Tool use helps reduce the amount of energy they expend.

Sea otters aren't the only species to use tools to prevent injury. Humans, of course, use tools constantly to prevent injury. Dolphins also do this. Some use sponges to protect their noses when digging for food in sand.