Hermit Crabs and Why They Must Fight For Those Seashell Homes!

Striped hermit crab
tiny hermit crab in conch shell

Tiny Hermit Crab in Crown Conch

If you read this blog, you have probably grown tired of me talking about hermit crabs, but here I go again!   Usually I am complaining that every awesome shell I come across out in the backwater is inhabited by a hermit crab.

This time I am going to tell (and show) you just how crazy things can get when hermit crabs fight for those seashell homes. It’s a crab vs. crab world down under the sea.

About Hermit Crabs

First of all, if you know next to nothing about crabs, here’s a bit of info.
Hermit crabs are not like regular crabs you find along the beach and catch to eat.  Stone crabs and Blue crabs, to name a couple of Florida regulars which are caught for food, don’t need shells of mollusks to survive.  Unlike hermit crabs, they scurry around without dragging a shell along.

It’s difficult to ever see the entire body of the hermit crab, as it is usually hidden within a shell.  A hermit crab will “hang” out of the shell sometimes, but he will not come all the way out except to swap shells.  This is because his back end is a soft rounded thing without legs.  If you are lucky enough to be present when he swaps his old shell for a new one, you can get a quick glimpse of the back end of his body.

When Sea Snails Die Their Empty Shell Becomes a Home For the Hermit

That shell it carries with it used to belong to a snail – land, or marine.  The hermit crab did not make the shell he lives in, and will stay in it only as long as he fits well inside.   Once the fit is too tight, he will have to find another shell to occupy.  His life depends on it.

The shell he moves into will have to empty… they don’t kill snails or mollusks to take a shell.  And they don’t fight other hermit crabs that are already inside a shell.

hermit crabs

Imagine that your present home will have to be abandoned as you grow.  You can’t stop growing, so it’s a constant hunt for a new place to live.  Without a shell to hide in, a hermit crab’s life is in peril.

In this NatGeo video, deceptively entitled “Hermit Crab vs. Conch”, a large Horse Conch chases down a tulip snail (banded tulip) and digests it. But the main story is about the hermit crabs who need to find new and larger real estate for their growing bodies. They realize that the horse conch will spit out the left over shell when he’s done eating the snail and they all want that house!

Did you see the shells those hermit crabs are scurrying around in? One was a pear whelk (yellow shell), and one was a shaped like a shark’s eye, or moon snail.

Here’s another amazing video of a hermit crab changing shells, but this one takes her “friends” with her!  Smart creature!  (This shell looks like some kind of knobbed triton.)

You may wonder why the crab doesn’t just find a big shell to live in so he won’t have to worry about trading out his home.  That won’t work because if the shell is too big, he can’t carry it around as easily.

Screen Shot 2017-06-12 at 2.28.54 PM

(Photo credits: Pixabay)

Striped hermit crab

18 thoughts on “Hermit Crabs and Why They Must Fight For Those Seashell Homes!

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    1. Dustytoes

      I see far too many hermit crabs… LOL, and I think you will have to visit a tropical location to view them.
      The photos are thanks to the generous photographers of Pixabay.
      It’s tough for me to get good photos when I’m out on the water. I don’t like to take my good camera, with all that salt water and sand around. But using my iPhone is dangerous too. The sun is so bright I am usually just guessing if the subject is in the frame..!

      1. Pete Hillman

        I know what you mean about sand and saltwater, especially when changing lenses, and if the wind is whipping sand around. I could do with a good all round camera really, for when I visit the coast.

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