The common hermit crab, pagurus bernhardus, is actually more closely related to lobsters than to crabs. They have a maximum body length of 3 inches (8 centimeters). The bodies of these creatures are yellowish, reddish and/or brownish in color. Due to the lack of a hard carapace (a hard upper part of the exoskeleton or a shell, like a turtle), they seek protection within the shells of gastropod mollusks. They also have a soft abdomen that is twisted asymmetrically to the right, short antennae, and 2 compound eyes that are located on moveable stalks. There are 2 pincers on the first pair of walking legs, with the right one being larger than the left.
The common hermit crab can be found in north-western Europe as well as around all the coasts of Britain. They will inhabit rocky and sandy areas both close to the shore as well as up to depths of 459 (140 meters). They often form a symbiotic relationship with a sea anemone, gaining increased protection while providing the anemone with improved food collecting in return. Whenever they move into a different shell (which they do as they grow larger), they will move the anemone with them. It is actually not uncommon for these animals to steal another hermit crab’s shell by forcing them out.
The diet of a common hermit crab consists of both plant and animal matter. They are also able to filter organic particles from the water and will even graze on periphyton (a type of algae). When faced with danger (such as a predator), these animals will retreat further into their shells and cover the opening with its walking legs. The right forceps are particularly helpful in barricading this entrance.
Breeding season for the common hermit crab takes place in January or February for those in more shallow waters. The ones that live deep underwater however, can be found carrying eggs throughout the year, meaning that there is no set breeding season for them. After mating, females will carry around the fertilized eggs (which are attached to the few abdominal legs) for up to 2 months before they hatch. The larvae may remain with their mother for a number of weeks after hatching before becoming independent and venturing off into the ocean on their own. Sexual maturity for the larvae is often reached before they are even 1 year old.
The common hermit crab is not an endangered (or even threatened) species. Their numbers are so vast that there are not any immediate concerns to their population in the wild. As with any animal however, special care must be taken so that they are not exploited or put in any other kind of danger that could have a negative impact on their status. With any luck, the common hermit crab can continue to thrive alongside humans and not ever have to worry about facing the possibility of extinction. After all, such a unique crustacean deserves to live and prosper for future generations to see.
Works Cited
“Common Hermit Crab” 9 August 2011
“Common Hermit Crab (Pagurus Bernhardus)” 9 August 2011
