blue crab is a decapod, which means it possesses ten appendages,
of which four pairs are segmented walking legs. Its last
pair of legs is paddle-shaped, permitting the crab to swim
more actively than most other crab species. These legs,
called the paddle fins, are flexible so that they can be
rotated in a sculling action that allows the crab to propel
itself through the water. The crab is capable of swimming
at burst speeds of up to one meter per second.
largest appendages are a pair of segmented arms ending in
pincer-like claws, which the crab uses for defense and to
grasp and crush prey. The carapace is the shell that covers
and protects the crab. Eyes, mouth, and antennae are located
at the front edge of the carapace.
have an outer hard shell called an exoskeleton. Unlike skin,
the hard shell can't stretch to accommodate growth, so the
crab must molt, or shed its shell, in order to grow. As
the crab grows, the shedding process occurs again and again,
as often as 25 times.