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Crabs

Page 1
Blue Crab
Calico Crab
Fiddler Crab
Ghost Crab
Page 2
Hermit Crab
Marsh Crab
Mud Crab
Stone Crab

Crabs of Galveston Bay

Crabs belong to the Phylum Arthropoda which is the largest phylum of animals with about one million known species and many remaining undiscovered. They have invaded all types of environments including the oceans. Marine arthropods, or crustaceans, encompass a huge variety of animals such as barnacles, shrimp, lobsters and crabs.

They have an exoskeleton that they must molt in order to grow. The old exoskeleton is discarded and a new one develops after the animal takes in water to expand itself. They also have jointed appendages such as legs and mouthparts.

The crab (as well as shrimp and lobsters) belong to the Order Decapoda (meaning "ten legs"). They have five pair of walking legs, the first is heavier and usually has pincers to get food and for defense. The body of most decapods is divided into two segments: The cephalothorax (the head-end) and the abdomen (the tail-end). In crabs, the abdomen is small and tucked under the broad cephalothorax. The abdomen is visible as a flat, V-shaped plate in males; in females it is expanded and U-shaped for carrying eggs.

They are typically scavengers, feeding off of detritus - bits of dead plant and animal material. Some crabs, such as the stone crab, have powerful claws to break the shell of snails.