Name: ラッコの幻想的な毛皮｜ディープルック (The Fantastic Fur of Sea Otters | Deep Look)
Uploaded: 2021-01-14T05:43:06.000Z
Duration: 3 min 24 s
Description: VoiceTubeの動画で発音を聞きながら英語表現を覚えよう！学べる英語：

Here’s one word to describe the Northern California coast: COLD.

If you or I were in those waves without a wetsuit right now,  we’d get hypothermia in minutes.

But sea otters have figured out how to survive here.

Which is amazing, especially  when you consider that this  little guy has to maintain an internal body

temperature around 100 degrees Fahrenheit.

Almost twice as warm as the water he’s swimming in.

Sure, whales do it. Sea lions do it. But those mammals have had tens of millions of years

Evolutionarily speaking, sea otters are newcomers... land animals that waded into the ocean a mere

Unlike other ocean mammals, they have no blubber.

And they’re small, meaning they are constantly losing heat.

Sea otters have the thickest fur on the planet. Up to a million hairs per square inch.

It also almost killed them -- back around the 19th century sea otters were hunted nearly

But it’s not really the fur, per se, that keeps the otter warm. It’s air.

Fur works by trapping air near the skin’s surface, like a down comforter.

Sea otter fur is so dense it’s basically waterproof. You can see how dry it is close

That layer of  air gives the otter’s fur a glossy look as it tumbles

Baby sea otters? Their fur traps so much air that they bob at the surface  -- their

fluffiness makes them buoyant. That is, until they shed the pup fur and learn to dive.

This excellent  insulation comes at a price.

Every time a sea otter dives, some of the air in their fur gets forced out -- see those

bubbles?  And so the otter has to groom himself all over again, to pump more air in.

As you can see, sea otter fur is actually made up of two kinds of hair: under fur, the

insulating part, and those  longer, protective guard hairs.

Under a microscope, you can see how the individual hairs are scaly and rough.

Those barbs on the hair shafts let the fur mat together.

For comparison - here’s a coyote. Coyotes, of course, don’t live in the freezing ocean,

Their fur keeps them warm on land, but they wouldn’t stay dry in the ocean.

In a lot of ways, otters have more in common with land animals.

But many years ago, otters took an evolutionary leap into these icy waters.