Hermit Crab Facts
Hermit Crabs, the decopods that borrow empty gastropod shells for use as homes, can be found in both deep ocean, near shore and land environments.
With hundreds of different hermit crab species found world-wide, they can vary in size from anywhere between one inch and one foot in length.
As they grow, hermit crabs replace one borrowed shell home for a larger version. A large hermit crab such as the white-spotted hermit crab of Hawaii might need a shell over a foot long.
Two hermit crab families, Paguridae (right-handed hermit crabs) and Diogenidae (left-handed hermit crabs) live along the coastal areas, with the difference between the two families determined by the hand with the largest claw.
The Giant Hermit Crab (Petrochirus diogenes) of the Southeast, Gulf of Mexico and Caribbean, grows to a length of up to eight inches.
It is the sole member of the Petrochirus genus in the family Diogenidae (left-handed hermit crabs), and it is the largest hermit crab found off coastal waters of the Continental United States.
Large hermit crabs require large shells for survival. The specimen in the top picture washed ashore inside of, what looks to be, a Florida Fighting Conch. They also use other local large shells such as tun-shells and whelks.
The top picture highlights the characteristic purple lines on the legs.
In the right handed hermit crab family, family Parguidae, some sixty different Pagurus species inhabit the world's coastal areas.
Because of their tendency to remain inside their adopted shell residence, identifying any particular species can be difficult.
The Hairy Hermit Crab (Pagurus hirsutiusculus), in the second picture is a fairly common resident of the West Coast of the United States.
The hair on the legs, along with the white bands serve as good field identification clues.
Finding hermit crabs in intertidal zones can be as easy as looking for a moving shell. They are scavengers that feed on algae and small invertebrates.
Of the approximately eight hundred documented hermit crab species, about sixteen are categorized as terrestrial (genus Coenobita).
Most Ceonobita inhabit areas of the Indian Ocean and Pacific Ocean. The Pacific Hermit Crab (Coenobita compressus) and the Caribbean hermit crab (Coenobita clypeatus) are popular in the pet trade.
Reaching a little over one foot in length, the Coconut Crab (Birgus latro), also called the Palm Thief or Robber Crab, ranks as not only the world's largest hermit crab, but also the world's largest land-living arthropod.
Young Coconut Crabs use shells to protect their bodies. However, the bodies of adult Coconut Crabs harden, removing the need to use protective shells.
© 2010-2011 Patricia A. Michaels