sentence: Crabs have very short tails.
sentences_after: A crab's tail and  reduced abdomen is entirely hidden under the thorax. It is folded under its body, and may not be visible at all unless the crab is turned over. Usually they have a very hard exoskeleton. This means they are well protected against predators. Crabs are armed with a single pair of claws.
concept_name: crab
headings: Crab Structure and life-style Body