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The crayfish moves about with ease, Backward and forward, to the side- Although he has ten legs, he can From danger very quickly hide. He moves his eyes, but not his head, And wears his skeleton outside!
YOU may find a crayfish resting quietly on the bottom of the creek, or hiding in the shadow of some rock. If you reach for him, he will move quickly away with a few jerky movements. He moves backward, forward, or sidewise, as he pleases. Because of his dark color, you can hardly find him in the shadow of the rock.
The dark, hard, brittle covering which a crayfish wears is all the skeleton he has. A frog's bony skeleton is covered with
muscles, but a crayfish does not have bones to cover. His skeleton is like a tough, hard skin which hides and protects the soft parts of his body. This outside skeleton is called an exoskeleton.
Have you noticed that the crayfish has no neck ? A hard shield covers his head and the forward part of his body. This shield is the largest piece of his exoskeleton.
Under the lower edges of the shield on each side are the breathing parts of a crayfish, which have been compared to bunches of tiny plumes. These are called gills. The oxygen which a crayfish breathes is taken from the water in which he lives. It passes through his gills into his colorless blood which carries it to all parts of his body.
The next time you catch a crayfish, put him in a dish of water and watch him closely. As he has no neck, he cannot turn his head without moving his body. His eyes are on movable stalks, so the crayfish moves his eyes instead of his head.
You will notice the two long antennae attached to the crayfish's head, which wave
about in the water. Besides these long antennae, each crayfish has a shorter pair, each of which is branched. He can move these as he does the larger ones. These, in addition to serving as feelers, appear to help the crayfish keep his balance so that he can move straight ahead when he wishes to do so.
A crayfish has five pairs of legs. You will notice that the first three pairs have pincers. If one of these little animals has ever caught your finger between his powerful pincers, you know how well he can use them to defend himself. Even with this protection, however, he may some day be eaten by a fish or by another neighbor who is stronger than he.
Perhaps you will find a crayfish that is growing a new leg or antenna to take the place of one that was broken off or lost in fighting.
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