HRAP Online Encyclopedia

Crabs and Shrimp

Oregon has a vast number of species of crabs and shrimp in all different shapes and sizes. Several of the larger species, like Dungeness crab and red rock crab, are commonly caught both commercially and recreationally. Others, like the mole crab - which resembles a large bug more than a crab - is an important prey species for local birds. The undersides of male and female crabs look different. Males have a triangle flap on their undersides while females have a rounder flap; these flaps are referred to as aprons. Female crabs carry their eggs under their aprons that have a larger surface area compared to males. All species of crab and shrimp have a hard exoskeleton and jointed legs. In order to grow larger, they all shed their exoskeletons periodically - these are called molts. In order to do this, they grow a new, bigger shell within the old one but keep it soft and flexible so they can bend and slip out of the old, smaller shell. With the new shell being soft, they are then very vulnerable for a bit until it hardens. The molts, that often look like an intact crab or shrimp, end up washed up on the beach, a fun discovery for a beach comber!

Crabs

Shrimp