Crab

Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (abdomen), usually hidden entirely under the thorax. They live in all the world's oceans, in freshwater, and on land. They first appeared during the Jurassic Period.

Crabs are generally covered with a thick exoskeleton, composed primarily of highly mineralized chitin, and armed with a pair of chelae (claws). Crabs vary in size from the pea crab, a few millimetres wide, to the Japanese spider crab, with a leg span up to 4 m (13 ft). Several other groups of crustaceans with similar appearance- such as king crabs and porcelain crabs- are not true crabs, but have evolved features similar to true crabs though a process known as carcinization.

Crabs are omnivores, feeding primarily on algae, and taking any other food, including molluscs, worms, other crustaceans, fungi, bacteria, and detritus, depending on their availability and the crab species. For many crabs, a mixed diet of plant and animal matter results in the fastest growth and greatest fitness. Some species are more specialized in their diets, based in plankton, clams or fish.

Crabs are prepared and eaten as a dish in many different ways all over the world. Some species are eaten whole, including the shell, while for other species, just the claws or legs are eaten. The latter is particularly common for larger crabs, such as the snow crabs. In many cultures, the roe of the female crab is also eaten, which usually appears orange or yellow in fertile crabs. This is popular in Southeast Asian cultures, some Northern European cultures and Guld Coasts of the United States.

Trivia

 * In some crab species, meat is harvested by manually twisting and pulling off one or both claws and returning the live crab to the water in the knowledge that the crab may survive and regenerate the claws.
 * Crabs are known to work together to provide food and protection for their family, and during mating season to find a comfortable spot for the female to release her eggs.