CRUSTACEANS 



quickly, insuring large additions to the copepod race; and 

 the resting eggs usually formed in seasons of cold and drought, 

 which can lie dormant even through years of drying. 



Fig. 127. — Common copepods: i , Diaptomus, often 

 found in spring-pools; 2, Canthocamptus. 



Copepods eat as much of as many kinds of food as their 

 small size will permit. They feed upon microscopic organ- 

 isms, and they will devour any kind of decayed matter, but 

 preferably decomposing plant tissue. Those which live 

 among the plankton (p. 19) on the surface of open water 

 are apt to be transparent and slender while ^hose which Hve 

 in the weeds near shore are shorter and often dark colored- 

 Some species of Diaptomus (Fig. 127) are red, blue or purple. 

 The greatest numbers of copepods are found from May to 

 early November. 



Aquarium study. — Cyclops is easy to keep in an aquarium 

 and is very useful there, being a natural food for small animals 

 such as the brown and green hydras which flourish on it (Fig. 

 87). The bladderwort, Utricularia, catches large numbers of 

 them in its traps (p. 102). 



167 



