Wednesday, July 2, 2008

Hermit Crab

We all have heard of the great sadhus and wise of the old. These Hermits are supposed to have meditated in a particular stance mostly a yogic position for even years! anthills were built around them but nothing deterred these people from stopping their meditation. They made them as their home.

Today's class is a
lso about one such crab. Its called the hermit crab.

Hermit crabs are crustaceans, not closely related to true crabs. As the normal ones have four pairs of walking legs while these have only three pairs along with having a long soft abdomen which is protected from predators by the adaptation of carrying around a salvaged empty seashell, into which the whole crab's body can retract. Most frequently hermit crabs utilize the shells of sea snails, marine gastropod molluscs. The tip of the hermit crab's abdomen is adapted to clasp strongly onto the columella of the snail shell. As the hermit crab grows in size it has to find a larger shell and abandon the previous one.

This habit of living in a second hand shell is what gave rise to the popular name "hermit crab", which is a reference to the idea of a hermit living alone in a small cave. Hermit crabs live in the wild in colonies of 100 or more, and do not thrive in smaller numbers.

The availability of empty snail shells at any given place depends primarily on the relative abundance of gastropods in the right range of sizes, compared to the demographics of the population of hermit crabs. An equally important issue is the frequency of organisms which prey upon gastropods but leave the shells intact. They are also very famous for their mutualism with sea anemone

There is also a video caught by me in the Andamans. Watch.