Soft-shelled crabs, as their name implies, do not have hard exoskeletons and can be eaten without needing to remove their shells.This is not, however, because they are a special, soft species of crab.Given what you know about exoskeletons, what else might explain this trait?

MCQs on the evolutionary history, phylogenetic relationships, comparative anatomy and physiology, and ecological interrelationships among animal taxa, as well as the evolutionary pressures that led to physiological and ecological differences among species and groups.