File:Hermet red crab.jpg

Crustaceans

There are bizarre shapes and adaptions in the world of crabs, also known as crustaceans. This sea animal group is best known for their hard outer shells and as it grows the shell must be removed. After this the new shell has to harden and during this period crabs are without its main protection, making them vulnerable to other predators. A few of the main predators are the teeth of a triggerfish and the beak of an octopus, which can crack the toughest crab shells. But crabs still have the claw, which is capable of exerting hundreds of pounds of pressure. Some crabs can stun their prey by producing a deafening miniature sonic boom.

Common crustaceans to be found on coral reefs:

•Arrow crab: bizarre looking creatures who get their name from the triangular shape of their bodies. They have long legs that can reach a span of about six inches, giving them a spider-like appearance. They are known for pulling feather duster worms out of their tubes.

•Red Hermit crab: this type of crab carries its shell (home) on its back and as it grows larger it must continually find new shells. They are very good scavengers so it feeds on most anything it finds. The abdomen is soft and vulnerable so it uses discarded shells to protect itself.

•Purple shore crab: this crab species is small and has a purple and red shell with a white underbelly and grows to be about 2 inches. It is commonly found on the open rocky seashores of the pacific coast of North America and it can be seen scavenging the seashore for algae and dead animal matter to feed on.