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Sea otters: Here’s what you otter know.

In honor of Sea Otter Awareness Week, an expert talks about these fluffy marine mammals.

A northern sea otter floats on its back while crushing a clam shell with its teeth in Seward, Alaska. Sea otters are probably larger than you may think. Northern sea otters can weigh up to 100 pounds; their southern cousins are up to 50 pounds for females, up to 70 pounds for males. (Dan Joling/AP)

It’s Sea Otter Awareness Week, which means it’s a great time to learn about everyone’s favorite aquatic fluffball! And the first thing you “otter” know about sea otters is that they are way bigger than you might think.

“The ones we have here in California are southern sea otters, and they can get up to four feet long,” says Chandler Rangel, an aquarist in the education department at the Monterey Bay Aquarium. “The females weigh up to about 50 pounds and the males up to 70 pounds.”

In Alaska, sea otters grow even bigger, with males tipping the scales at about 100 pounds, says Rangel, who has worked in marine mammal rescue and rehabilitation. That means a sea otter is roughly the size of a fourth-grader.

Sea otters are also incredibly hairy. “They don’t have any blubber, like most marine mammals do, and our waters here in California are very, very cold,” says Rangel. “That’s why sea otters have up to 1 million hairs per square inch. Humans only have about 100,000 hairs on our entire head.”

Because it’s so thick, sea otter fur is warm and waterproof. It’s also super-soft, which has made the animals prized targets for fur-trappers.

In fact, sea otters were nearly hunted to extinction in the 1700s and 1800s. Fortunately, people realized the animals were almost lost, and the United States government added several otter species to the endangered species list beginning in the 1970s. Today there are about 3,000 southern sea otters living on California’s coast.

And that’s good news, because sea otters are eco-superstars. “Other than just being cute and cuddly and being great tourist attractions, they actually play a very important part in their ecosystems,” says Rangel.

This is because otters love to eat invertebrates, such as sea urchins, which in turn like to eat kelp forests that grow in coastal waters. When otters disappear from these areas, the urchins multiply so much that they can eat an entire kelp forest. “When the kelp’s gone, nothing else can really live there. And that just destroys the entire habitat,” says Rangel.

A final fascinating fact: Sea otters learn to eat what their mothers eat, and they have different tastes. Some like purple urchins, for instance. They eat so many of the dark, pincushion-like creatures that the sea otters’ teeth and bones turn purple.

It’s “an-otter” example of “you are what you eat.”

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