sea otter

Sea Otters Use Tools To Combat Food Competition Amid Climate Change, According To Study 

In certain parts of the ocean, sea otters are facing major competition for food, partially due to climate change limiting food supplies. However, they’ve adapted by utilizing “tools” such as rocks or even glass bottles to open tougher prey, like clams, giving them an opportunity to maintain their diet. 

These observations were recently published as a part of a new study published in the journal Science. The study analyzed sea otters in Monterey Bay, California, and was specifically looking at how individual otters used various tools they found, and how utilizing them impacted their health and nutrition. 

The findings also concluded that this skill set could increase sea otters chances of survival in ocean environments that are constantly changing as a result of climate change. 

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Sea otters often spend their days foraging for food in kelp forests by diving to the bottom of a body of water to grab morsels of food and rocks that they can use as tools. The study stated that they then bring their food and rocks to the surface of the water, float on their backs, and use their stomach as a table to open and eat their snacks. 

“Their preferred prey are usually urchins and abalone,” says Chris Law, a biologist at the University of Texas and the University of Washington involved in the study. 

Law stated that urchins and abalones are a part of sea otters diets and are typically easy for them to break apart and open. 

“Unfortunately, all those prey items have been declining or have declined,” especially in highly populated areas like Monterey Bay, says Law.

A big part of a sea urchin’s diet is kelp, and they can consume a lot at a relatively quick rate. When large groups of urchins go through a kelp forest, they can completely decimate it, which can in turn make the urchins “calorie-poor” with little nutritional value for the otters that consume them. 

“So that means otters have to eat alternative foods. A lot of those alternative foods are those super-hard-shell prey items that really require some kind of external force to break into,” said Law. 

Law added that “snails are abundant in the bay, but they’re low-calorie and basically like a rock that you have to break into to eat the insides.”

Law and his colleagues looked at data from 196 otters in Monterey Bay. They tagged the otters, and volunteers involved in the study monitored the marine mammals closely to see what they were eating, how large and tough their prey is, and if the otter utilized a tool to eat it. 

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According to the report, otters who used tools were able to eat larger prey. Female otters’ use of tools is important for their overall nutrition because they’re smaller than males and don’t have the ability to bite down as hard.  

“They [female otters] typically wouldn’t be able to break into harder prey. But they use tools more than males, so they’re able to gain access to these novel sources of food items,” said Law. 

The use of tools also work to protect otters’ dental health. The otters monitored in the study received dental assessments as well, and the researchers found that those who used tools had less damage to their teeth than those who didn’t use tools, because they just bite down on the hard shells to break them open. 

“Without their teeth, they clearly can’t eat anything. So then they die. What we’re suggesting is that this behavior really allowed them to continue living on despite not having their preferred prey.”

“This is such an important paper,” says Rob Shumaker, president and CEO of the Indianapolis Zoo and one of the authors of a book called Animal Tool Behavior.

According to NPR, he said “scientists have spent decades documenting tool use in dozens of species; tool use in sea otters, for example, has been recognized since the 1960s. But now, studies like this one are showing that this field of research is starting to shift.”

“It’s not about describing the actual tool use or tool manufacture anymore. It’s describing the impact that it has on that animal’s life.”