Crayfish molt because they must shed their hard exoskeletons and grow new, larger ones as their size increases. During the first year of life, a crayfish molts six to 10 times. This number decreases to three to five times during its second year.
When a crayfish molts, it is very vulnerable for several days. It spends two to three days inactive in its home to avoid injury and predators before emerging with a strong new exoskeleton. In order to support their rapid growth, young crayfish take in 1 to 4 percent of their body weight each day. Adult crayfish only need to consume 0.3 to 1 percent of their body weight each day.