FOOD AND FEEDING 



FIG. 67. Polyphemus 

 pedeculus. Greatly enlarged. 



caying vegetation, organic ofFal and small infusoria. They are the best 

 food for the goldfish. It has been noticed that the tiny newly hatched 

 alevin will follow Daphnia to feed upon the young as they are released 

 from the brood pouch of the female. The most generally distributed 

 forms are Daphnia l^evis, D. pellucida, D. pulex, Daphnella branchyura, 

 Ceriodaphnia pulchella and Sida crystallina. 



Polyphemus. Fig. 67. One species of Polyphemus is quite gener- 

 ally present in still and stagnant water. This is P. 

 pedeculus, of which the body is of most grotesque form, 

 owing to the peculiar humplike brood pouch. It is 

 smaller than the Daphnia, about .65 to i millimeter in 

 length. 



Leptodora. Fig. 68. One form of Leptodora 

 is quite generally present in larger bodies of freshwater, 

 and may be taken on the surface on bright days. The 

 body is long and is covered by a faintly segmented carapace. There are 

 two long swimming legs and the very long antennae branch at the ends and 



are furnished with swimming bristles. 

 L. hyalina is the most generally dis- 

 tributed form. Its length is about 

 I to 1.5 millimeters. 



Sub-Order Ostracoda. Com- 

 pressed body small, indistinctly seg- 



FIG. 68. Leptodora hyalina. Greatly enlarged. mentcd, in a bivalvC shcll, fivC pairS 



of feet adopted to swimming and creeping. The freshwater form is Cypris. 

 CypRis. Fig. 69. Several species are very generally distributed and 

 may be taken from almost every water which contains the other entomos- 

 traca. The body is unsegmented and is enclosed in a carapace articulated 

 at the dorsal edge to form a bivalve shell. At 

 the anterior end is a median eye, and there are 

 seven pairs of swimming appendages. Its size is 

 I to 1.5 millimeters, and its movements are slow 

 and leisurely either In swimming or In crawling 

 over the bottom. The young are developed in 

 the brood pouch but are expelled In the larvel 

 condition. This Crustacean propagates even more 

 abundantly than the Daphnia, and will prey upon the eggs and embrios 

 of fishes, a number of them may attack an alevin, fastening themselves 

 to its surface and devouring it in spite of efforts to free itself. Goldfishes 

 eagerly eat the Cypris. The generally distributed forms are Cypris virens, 

 C. pubera, C. pellucida, C. fusca and C. ornata. 



FIG. 69. Cypris virens. 

 Greatly enlarged. 



