What is Hermit crab?
{{Taxobox | name = Hermit crab | image = Hermit crab corcovado.jpg | image_width = 250px | image_caption = A hermit crab from [[Costa Rica]]. | regnum = [[Animal]]ia | phylum = [[Arthropod]]a | subphylum = [[Mandibulata]] | classis = [[Crustacea]] | subclassis = [[Malacostraca]] | ordo = [[Decapoda]] | subordo = [[Pleocyemata]] | infraordo = [[Anomura]] | superfamilia = '''Paguroidea''' | superfamilia_authority = [[Pierre André Latreille|Latreille]], 1802 | subdivision_ranks = [[Family (biology)|Families]] | subdivision = * [[Coenobitidae]] * [[Diogenidae]] * [[King crab|Lithodidae]] * [[Paguridae]] * [[Parapaguridae]] * [[Pylochelidae]] * [[Pylojacquesidae]] }} The '''hermit crab''' is a type of [[crab]] that does not have a hard shell. They use old shells for protection. They especially like old [[whelk]] shells. When the hermit crab grows in size, it finds a larger shell. == Description == The hermit crab is a [[crustacean]], but it is very different from other crustaceans. While most crustaceans are covered from [[head]] to [[tail]] with a hard [[exoskeleton]], the hermit crab is missing part of its exoskeleton. The back part where its [[abdomen]] is located, is soft and [[wikt:squish|squishy]]. Thus, the minute a hermit crab [[wikt:molt|molt]]s into an [[adult]], it sets out to find a [[Animal shell|shell]] in which to live. To get into the shell, the hermit crab squeezes in backwards, using its four back legs to enter the shell. The back legs have hooks that [[anchor]] the hermit crab into the shell without [[wikt:trouble|difficulty]]. The next four legs are used for walking, while the front two are its [[wikt:cheliped|chelipeds]]. The chelipeds are not equal in size: one is big and other is small. The larger one is used for grabbing [[wikt:prey|prey]] and [[wikt:guard|guard]]ing the entrance to its [[Animal shell|shell]]. All together, hermit crabs have a total of ten legs, including the chelipeds and the rear legs used to anchor to the shell. There are about 500 different [[species]] of hermit crabs a