Sunday, July 22, 2018

The Ultimate Shopaholic: A Hermit Crab

Hairy red hermit crab in an empty triton shell eating a shrimp.

Family Ties

Hermit crabs are crustaceans, a class of animals that have segmented bodies and an exoskeleton (a hard outer covering).  They are related to lobsters, shrimp, and other crabs.  But hermit crabs are special.  

Unlike other crustaceans that have an exoskeleton covering their abdomen, the last third of a hermit crab's body is soft and exposed.  To protect itself, the crab looks for an abandoned shell.  Once it locates a shell that fits, the hermit crab wriggles inside and walks off with a happy abdomen.

The shell comes in very handy when the hermit crab gets scared.  It can withdraw it's whole body inside to hide, hence the name hermit crab. 

Hermit crabs can withdraw into their shell for protection.

Home Sweet Home

Some hermit crabs live on land and others live in the water. There are many species that live in the ocean.  The ocean dwellers have a special way of protecting themselves.  Often times they will allow a sea anemone to set up residence on the top of their shell.  Sea anemones sting predators with toxin for protection.  Having an anemone on your side comes in handy.  

A Picky Shopper         

Hermit crabs make good pets.  But be sure to keep some empty shells on hand.  As the crab grows, it will need to move into a bigger shell. It would be good to have several choices available.  

I recently observed a hermit crab switching shells in the aquarium where I work.  The crab spent over an hour examining one particular shell. First it spun the shell around and around checking it from top to bottom.  Next it circled the shell to view it from front and back.  Finally it stuck its claws inside the shell, feeling as far back as it could reach.

The crab repeated this scenario again and again before it was ready to make its move.  Once the decision was made, it didn't take long. In about 10 seconds the little crustacean had slipped out of its old shell into its new home.  Then off it crawled, until---alas!  The shell wasn't quite right.  The crab crawled back to its old shell and climbed inside, then off it went to continue the search.

If you're looking for a interesting pet, check into this amazing little critter. 

Research Credits:

1.  "Land Hermit Crab".  Smithsonian's National Zoo & Conservation Biology Institute.  Smithsonian.  Web.  13 Jul. 2018.  < >.

2.  "Why Do Hermit Crabs Live in Borrowed Shells?" Wonderopolis: Where the Wonders of Learning Never Cease.  National Center For Families Learning.  Web.  13 Jul. 2018. <>.   

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