Dec, 1921 FOOD of ohio darters 59 



equipped for the purpose with fine gill strainers. Some of the 

 darters feed upon entomostraca to some extent in the adult 

 stage but there are none that may be classed as feeding exclu- 

 sively upon very small objects. An examination of the gill 

 strainers in the different species listed here failed to show any 

 marked differences. 



The position of a terminal mouth, especially if the lower 

 jaw is projecting, also seems to be correlated definitely with the 

 habit of taking large and active food. Etheostoma flaheUare is 

 the most specialized in the development of a projecting lower 

 jaw and it has developed the habit of taking large, active food 

 animals more than any other. Etheostoma coeruleum is some- 

 what less specialized in both its food habits and the devel- 

 opment of a terminal mouth but it resembles E. flabellare. 

 Boleichthys fiisiformis was taken in a situation where vegetation 

 and debris were most abundant, but a very small trace of either 

 appears on the food. It is a remarkably clean feeder for the 

 environment and seems to have developed nothing of the grub- 

 bing habit, although it is bottom feeder. 



{d) Special Habits. 



All of the darters are considered to be very agile fish, but 

 even among the members of an active group there are some 

 that are more active than others. The difference in the ability 

 ot the fish to overtake and seize food animals would be reflected 

 in the food. Of the list given here Etheostoma flabellare is the 

 most active and the large, active food animals that appear in 

 the diet are not taken by any other darter. 



The habit of feeding upon the bottom seems to be well 

 established in the adults of most species but there is a differ- 

 ence even here. Some of the fish have developed a habit of 

 grubbing upon the bottom so that a large amount of debris 

 appears incidentally in the food. Boleosoma nigrum is one of 

 this sort. Others may live in the midst of debris and select only 

 live, active food. Boleichthys Jusiformis illustrates this type. 



Percina caprodes in its very early stages is a surface feeder 

 like the younger stages of the perch and black bass but as it 

 matures it becomes a bottom feeder. Others like Etheostoma 

 flabellare and Boleichthys f.iisijormis seem to be bottom feeders 

 from the time that they hatch. This difference in habits has its 



