LAKE AND RIVER IN WINTER 299 



A crayfish has five pairs of legs. Observation of a live 

 crayfish will teach you that the first pair, which are modi- 

 fied into the dreaded claws or pinchers, are not used for walk- 

 ing, but are offensive and defensive weapons. You can 

 often see crayfishes walking slowly over the bottom ; when, 

 however, they wish to escape from danger, they strike the 

 water downward with their tail and swim rapidly back- 

 ward. The mouth of the crayfish is a rather large opening 

 under the head ; it is large enough to admit the head of a 

 large pin, and is surrounded with very complicated prehen- 

 sile and masticating organs. 



The eyes of the crayfish are black and set on little stalks ; 

 they can be moved in all directions, and, when danger 

 threatens, they are laid down in a furrow under the point 

 of the head shield. The head is also provided with a pair 

 of long, thread-like feelers, or antennae. These long an- 

 tennae are delicate organs of touch. Just above them is a 

 pair of shorter antennae, which contain the organs of hear- 

 ing. It is also highly probable that crayfishes can smell 

 and taste, but the organs for these senses have not been 

 made out with absolute certainty. 



The color of the crayfish is a dark olive-green, which 

 blends very nicely with the weeds and stones among which 

 it lives. Crayfish very often live in holes, which they dig 

 near the water. If the water dries up temporarily, they 

 dig their holes deeper, until they reach moisture. If you 

 remove the carapace of a crayfish, you will find the feather- 

 shaped gills below it. By means of these gills the animal 

 can breathe in air as well as in water, as long as its gills 

 are kept moist. Transporting live crayfish is accomplished 

 much better by putting them in wet grass or leaves than by 

 keeping them in a pailful of water. You can induce the 

 crayfish to leave their holes by stamping around them or 

 by pouring water into them. 



