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The Hermit Crab: A Crabby House Hunter
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By:
Margarita M. Espiritu
Summer time in a tropical country can only mean one thing to many of us, frequent family vacations to the beach! And most of us know that this does not only include swimming and building castles in the sand for pastimes. Going to the beach gives us the opportunity to comb the shoreline in hopes of discovering interesting creatures as well. One such creature, which we can see scuttling about this way and that, is the hermit crab.
 The tiny land hermit crab, also known as the soldier crab for temperamental reasons, can only grow up to three inches long. It is part of the Crustacean family, which is a group of animals whose skeletons are on the outside of their bodies. Some crustaceans live in saltwater and breathe through gills, just like fish. They have many pairs of legs, and their bodies are jointed, like a human's elbows or knees. Crabs, shrimp, lobsters and barnacles are all crustaceans. Some crustaceans can swim, like crabs and shrimp. Some can only scuttle along the ocean floor, like the lobster. And the barnacle sticks to a hard spot and never moves at all. The hermit crab is also a crustacean, but he does not grow his own shell. He has to find empty shells of other animals to move into.
The birth and the growth of the hermit crab can be compared to that of the tadpole. Both are hatched from eggs in the water, in the hermit crabs' case, it is hatched in the ocean. And both do not look anything like its adult counterpart. The zoea (zo-ee-a), or the newly hatched hermit crab is long, slender with two large eyes and a pointed snout. Like the tadpole that lives in fresh water, the hermit crab lives in the ocean for a short period of time until it matures. Slowly the hermit crab will not need to go to the ocean anymore and will live on land. An adult hermit crab gets his water from tidal pools and rain puddles and can only be submerged in water for a short while, after which he will already drown. As he grows, he will eventually seek residence in a shell.
The hermit crab, unlike most armored crabs needs a shell shack to protect its soft and defenseless back and stomach. He usually picks snail shells as homes. Having to live in small, cramped places the hermit crab has evolved to having only one large pincer because there is no room for two. The one large pincer that he has serves as a sword for keeping enemies at bay. When feeling threatened, he tries to retreat as far back into his shell as possible and uses his strong and fully armored pincer as guard. He uses this pincer as protection against other predators or other hermit crabs that are interested to move into his own dwelling.
Hermit crabs are a bit of a bully. A crab that gets too big for his shell embarks on a ruthless house hunt. He checks all the shells in the vicinity, whether empty or not. If he has his eye on one shell that has an inhabitant still living in it, he stops at nothing. If a snail still lives in a shell, the hermit crab will devour it. If another hermit crab still lives in a shell, then a long battle, sometimes to the death, ensues. Some brave and stubborn hermit crabs would prefer to have their pincers pulled out in combat rather than to give up his home. Some however are not much into wrestling so they soon leave their homes and scuttle to the nearest rock to find temporary protection for their nakedness, while the victor quickly and nervously moves into the home he had conquered.
The hermit crab is also a bit of a shopper. He is very selective when picking his shell "home". He may spend an hour or two "touching" the prospective home with his legs and antennae. He may move into the new shell, only to decide that he liked his old shell better, and starts window-shopping once more. Some however seem to have simpler and more practical taste. A certain hermit crab was once seen living in an empty can! Remember the saying, "One man's trash is another man's treasure?" Well, this seems to be the case for this particular imaginative hermit crab. That's recycling at its best!
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