Crabs must molt because their hard, calcified exoskeleton cannot grow with them. Before molting, they reabsorb calcium and weaken their old shell from the inside. During ecdysis, they painfully pull ...

Blue Crab on Beach of Florida© Katarina_G/Shutterstock.com A crab’s exoskeleton protects it like armor and gives the animal structural support. Without the process of molting, crabs and other ...