Did you know that a crab has ten legs, unlike spiders, which have eight? The first pair of legs on these animals form a pair of claws. These crustaceans have an exoskeleton, which means their bones are on the outside instead of the inside, acting as a kind of shield. The abdomen and thorax are joined together, which is quite unusual, although there are a few breeds without this feature. Males have narrow abdomens and females have wide ones.
