The furriest animal on Earth

I was entranced by the sea otters (Enhydra lutris) I saw on my recent visit to the California coast, and looked up some facts about them. One thing that astonished me was the almost unbelievable thickness of their fur.

The facts from BBC Earth, referencing a paper in Acta Theriologica:

In a 2010 paper, researchers compared the hair densities of Eurasian otters and sea otters. They found that Eurasian otters have up to 80,000 hairs per square centimetre of skin, while sea otters have an astonishing 140,000 hairs per sq cm.

By comparison, Arctic foxes and chinchillas both have 20,000 hairs per sq cm, and a muskox has just 420 per sq cm. Clearly, the sea otter is the furriest creature on Earth.

Since 1 cm² = 0.155 inch², this means that (as confirmed by other sources), sea otters have 140,000/0.155 or a bit more than 900,000 hairs per square inch on some parts of their body. This comports with other sources, like SeaWorld, which says this:

Sea otters have the densest fur of any mammal. Hair density varies dramatically with location on the body, ranging from about 26,000 to 165,000 hairs per square centimeter (170,000-1,062,000 per square inch).

Imagine that! I can’t even conceive of it: imagine taking one square inch of sea otter skin and counting a million hairs!  In comparison, Leaf notes that the average human has 2,200 hairs per square inch, or 100,000 on the entire head. That’s just 1/10 the number of hairs on one square inch of an otter’s body, so that otters have a hair density about 450 times that of humans.

Of course, the otters need them because they inhabit cold waters and rarely leave the ocean; the fur is for insulation.

The density of those hairs is also responsible for the near-extermination of sea otters for their fur, which took the population down to between 1000 and 2000 individuals in the early 1900s. Now, thanks to conservation, the species is up to about 100,000 individuals compared to the historical estimate of 150,000-300,000. They’re still classified as endangered, though.

29 Comments

  1. Posted January 24, 2019 at 2:26 pm | Permalink

    Not only the furriest, perhaps the cutest. I guess cuteness didn’t count for much when their pelts were so valuable.

    • gravelinspector-Aidan
      Posted January 25, 2019 at 9:45 am | Permalink

      Surely a Just God (a friend of the Oh God, of hangovers?) would have completed the hat trick and made them tasty too?
      Is the hair long enough to shear them, like sheep? I’m sure someone has tried. Probably after trying cockroach milking.

  2. mikeyc
    Posted January 24, 2019 at 2:41 pm | Permalink

    Unlike most marine mammals, Sea Otters don’t have blubber. So they really need that thick fur. It also means they must eat a LOT, diving and munching almost constantly with very cute floating naps in between their many meals.

    • Posted January 25, 2019 at 11:21 am | Permalink

      I had wondered about the blubber. (Or as it turns out lack of.) Interesting.

  3. Barbara Radcliff
    Posted January 24, 2019 at 3:12 pm | Permalink

    Help! Was there no Hili dialogue today? I can’t find it, and my morning coffee just didn’t taste the same!

  4. Ken Kukec
    Posted January 24, 2019 at 3:22 pm | Permalink

    … the average human has 2,200 hairs per square inch, or 100,000 on the entire head …

    Wonder what Ronald Reagan’s hair count was. Never cared much personally for the Gipper’s presidenting (though compared to what we’ve got now, he seems like Pericles in the Golden Age of Athenian democracy), but the son-of-a-gun had a helluva head of hair right through into his dotage, gotta grant him that.

    • Ken Kukec
      Posted January 24, 2019 at 3:40 pm | Permalink

      I’m gonna guess somewhere south of a sea otter but north of a chinchilla, though don’t cite me as an authoritative source on that.

      • Adam M.
        Posted January 24, 2019 at 6:08 pm | Permalink

        😀

        Gotta say that you’re one of the most colorful and intelligent commenters around, and we’re lucky to have you.

        • rickflick
          Posted January 24, 2019 at 6:52 pm | Permalink

          +1

        • Mikeyc
          Posted January 24, 2019 at 10:20 pm | Permalink

          You got that right. I’d like to see his music collection too.

    • Posted January 24, 2019 at 7:42 pm | Permalink

      Trump’s hair count, of course, is extremely low…

      • W.Benson
        Posted January 24, 2019 at 8:26 pm | Permalink

        Best comment today!

        • Glenda Palmer
          Posted January 24, 2019 at 8:42 pm | Permalink

          Jeez, it just dawned on me that if he shaved his head he would look like Benito Mussolini.

          • rickflick
            Posted January 24, 2019 at 8:53 pm | Permalink

            More than look like…

            • Posted January 24, 2019 at 9:00 pm | Permalink

              Indeed!

              • rickflick
                Posted January 24, 2019 at 10:04 pm | Permalink

                I can see that a helmet would come in handy for tRump.

      • rickflick
        Posted January 24, 2019 at 8:42 pm | Permalink

        The operative term is “sparse”.

  5. Merilee
    Posted January 24, 2019 at 3:59 pm | Permalink

    🐾🐾

  6. Heather Hastie
    Posted January 24, 2019 at 4:15 pm | Permalink

    I adore sea otters – they’re in my previously mentioned top ten of all animals. I wish we had them in NZ.

  7. Joe Dickinson
    Posted January 24, 2019 at 6:41 pm | Permalink

    Definitely way up on cuteness, but not quite so much when they are in the middle of dismantling a crab.

  8. Joe Dickinson
    Posted January 24, 2019 at 6:43 pm | Permalink

    Oh, and I think the dense fur my trap air that helps them float without the need to swim constantly.

    • Posted January 25, 2019 at 5:58 am | Permalink

      This is particularly so for the pups whose coat traps so much air they are essentially unsinkable. This enables the mothers to leave the pups bobbing on the surface while they dive to forage.

  9. Posted January 25, 2019 at 4:36 am | Permalink

    Definitely way up on cuteness, but not quite so much when they are in the middle of dismantling a crab.

  10. Posted January 25, 2019 at 8:57 am | Permalink

    I suppose that there is a unit of measurement for insulation strength but an’t think of what it is. I wonder how a sea otters fur compares to a penguins feathers.

  11. Katey
    Posted January 26, 2019 at 9:45 am | Permalink

    While the fur density of sea otters is mindblowing, trust me when I say a chinchilla’s paltry 20,000 per sq cm is plenty impressive when they shed all over your house!

  12. Posted February 20, 2019 at 2:19 pm | Permalink

    Adorable , I love how they care for each other.


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