Scavengers of the reef, Crabs and Shrimp are crustaceans. Related to land animals like spiders, scorpions and centipedes,they are one of the most important groups living on coral reefs.
Typified by a rigid external skeleton, they periodically outgrow their shells and molt. Shedding the old shell, the animal is particularly vulnerable until the new shell hardens.
Most have limbs which are jointed allowing movement in all directions.These are used for feeding, locomotion, touch and chemical reception. Most often they will have walking legs, 2 pair of antennae,and pincer like claws.