Dec, 1921 FOOD of ohio darters 45 



mostraca are eaten, with the insect larvas and the amphipods 

 gradually predominating. In the last stage the diet becomes 

 very complex with the larger insect larvas and amphipods fur- 

 nishing the larger proportion of the food while the quantity of 

 entomostraca becomes negligible. Although the quantity of 

 entomostraca definitely decreases, a few are eaten even by the 

 largest fish and an occasional individual is found which has 

 eaten little else. 



The specimens taken from the inland lakes were fewer in 

 number but were more developed, none being smaller than 

 30 mm. The food habits of this group closely parallels that of 

 the Lake Erie group but there is one outstanding, if minor, 

 difference. Entomostraca do not play nearly so constant a 

 part in the diet although there is a larger proportion eaten by 

 the smaller fishes. It is to be noted that the waters of the inland 

 lakes are much more concentrated in their production of insect 

 food than those of Lake Erie and it is possible that the Lake 

 Erie fish are compelled to rely upon Entomostraca in the 

 absence of insect food. 



Some interesting variations in food habits are offered by the 

 fishes from the streams. 1. The food is less varied in the stream 

 fish. 2. Entomostraca are eaten constantly but in a very small 

 proportion while midge and May fly larvse furnish almost the 

 whole food in many cases. 3. Amphipods are wholly lacking 

 in the food of the stream fishes. 4. There is a proportionately 

 large amount of molluscan food taken. 5. Planorbis and Physa 

 are the principal snails eaten by the specimens from Lake Erie 

 while Ancylus is the only snail taken by the stream fishes. 



Summary of Food Habits in Percina caprodes. 



1. Younger specimens subsist mainly upon entomostraca. 

 2. Insect food and entomostraca are taken by the intermediate 

 individuals. 3. The larger specimens have a more complicated 

 diet but entomostraca are continued as a constant though small 

 item and insect larvas form the principal constituent. 4. Spec- 

 imens from the inland lakes vary somewhat from the course 

 followed by the Lake Erie specimens. 5. Fishes from the 

 streams differ markedly in their food habits from those from 

 Lake Erie and the inland lakes. 



