The crab is a decapod crustacean which lives in the coastal areas of salty, fresh and brackish waters.
The crabs are generally covered with a thick exoskeleton and armed with a single pair of claws.
There are two kinds of crabs. First are true crabs which have short abdomen and use four pairs of long legs for walking and second are false crabs.
The latin word "cancer" is related to the word "crab" in Latin and both the constellation Cancer and the astrological sign are named after the crab.