300 HANDBOOK OF NATURE STUDY 



The food of the crayfish consists of snails, insect larvae, 

 tadpoles, small frogs, dead animals, and aquatic plants. 

 Crabs should be kept in an aquarium by themselves, be- 

 cause they are likely either to eat or to injure other small 

 aquarian animals. 



During the winter, crayfish hide themselves. They re- 

 appear in early spring, and at this time the females are 

 laden with eggs, which they carry beneath the tail, and 

 which look like a mass of small berries. The eggs hatch 

 in May or June, and the young, which closely resemble the 

 adults, attach themselves to the mother for several days. 



After a crayfish has been boiled, its calcareous shell looks 

 red, and can now be easily separated from the white flesh 

 within it. Vertebrate animals have their bones surrounded 

 by flesh, but you see that the crayfish has its flesh sur- 

 rounded by bones. The flesh and blood of the crayfish are 

 white. How do you think this animal can grow in its 

 tightly fitting armor ? You can easily convince yourself 

 that it will not stretch. Once or several times a year, the 

 crayfish casts off its old integument. It splits below, and 

 the animal crawls out of it, and pulls its legs, feelers, and 

 eyes out too. Frequently you will find the crust, which 

 looks just like the animal in shape, but is of a lighter color. 

 It is not rare that one or more of the legs are broken in the 

 process of moulting; but this does not seriously incon- 

 venience our armored knight, as he has the peculiar power 

 to repair any limb which has become detached or mutilated. 



We must place the crayfish among the useful animals, 

 because it acts as a scavenger in the water, and furnishes us 

 with palatable food. 



Teachers and pupils who would like to study aquatic animals are 

 referred to the very interesting book, Fresh Water Aquaria, by G. 

 C. Bateman. Though intended for England, it serves very well for 

 this country. 



