• Hermit crabs are prey for a wide variety of predators.Hermit Crab image by Bobbybigfish from Fotolia.com
  
  Hermit crabs are one of the most widespread crustaceans on the planet. There are over 500 different species, ranging in size from just a couple of centimeters to the size of a coconut. They do not grow a protective shell of their own but instead salvage a sea shell from the ocean floor, which they carry on their backs. They can retract their whole bodies into the shell when threatened. As they grow they replace the shell with a bigger one. Their favored environments are shallow sand- or mud-covered marine water, primarily in the intertidal zone, although they are also able to survive on land and some species are able to climb trees.
  
  

Marine Predators

• A wide variety of fish will eat hermit crabs, including yellow-fin tuna. Some are even able to eat them shells and all. Octopuses are also common predators of the crabs, their beak-like mouth parts adept at shattering the shell to get to the soft body of the crab inside. Turtles are also able to do this in order to consume the crab. Another significant predator is larger true crabs, those that grow their own shell, and, indeed, other hermit crabs.
  
  

Aerial Predators

• All manner of birds that live along coastlines, primarily seagulls and wading birds, will eat hermit crabs if they can catch them in the shallow water or on land. Birds' beaks are particularly effective at pecking the crab to death in its shell so that it will no longer secure itself inside and can be consumed.
  
  

Land Predators

• On land, hermit crabs are often eaten by opportunistic hunters such as rats. They are also part of the diet of omnivorous reptiles such as the cane toad and large lizards. They may also be at risk, in certain areas, from domestic pets such as dogs and cats.
  
  

Defense

• The shell they live in is the only real defense the hermit crab has against predators. Some hermit crabs, however, have taken to augmenting their protection and using shells that already have sea anemones living on them, the stinging tentacles of the anemone serving to ward off predators. In return, the anemones are able to feed on scraps that float up from the crab's meals.