characteristic of the crustaceans is a “shell” or
cuticle made up of chitin, a network of
molecules that are something of a hybrid
between carbohydrates and proteins. In
shrimp, the cuticle is thin and transparent; in
larger animals it’s thick and opaque, hardened
to a rock-like mass with calcium minerals
filling the space between chitin fibers.
Crustacean anatomy. The forward part of the
crustacean body, the cephalothorax or
“head,” contains the digestive and
reproductive organs. The rear part, the
abdomen or “tail,” is mainly fast muscle
tissue that moves the rear fins and propels
shrimp (top) and lobsters (center) in brief
swimming maneuvers. The crab (bottom) has
only a vestigial abdomen tucked under its