Author Institution: Zoological Laboratory, Beloit Colleg

Turner, Clarence L.

The Ohio Journal of Science

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NOTES ON THE FOOD HABITS OF YOUNGOF COTTUS ICTALOPS (Millers Thumb.)C. L. TURNERZoological Labaratory, Beloit CollegeWhile the writer was engaged in collecting the fry of thePerch and of the Darters in the vicinity of Put-in-Bay, pre-paratory to making a study of their food habits a locality wasfound in which the young of Coitus ictalops were fairlyabundant.Around the shores of Buckeye Island there is an abundanceof short, thick vegetation, shaded by willows and protectedand held together by willow roots. This margin is constantlyawash due to the exposed position of the island. The young ofGottus ictalops and of the Fan Tailed Darter (Etheostomaflabellare) were found hiding in the vegetation and under therocks in the vicinity. It was not possible to take the fish in aseine because they were so well protected but a small collectionwas secured by persistently dragging the vegetation with a flatended dip net.About a hundred specimens were taken ranging in size from12 to 22 millimeters and the stomach contents of thirty-fivewere examined. The food articles have been arranged in atabular form showing the proportion of each kind of food eatenby each size of fish.•—Although ten" different articles occur in the food some ofthem are almost negligible in quantity and even the youngestfish seem to prefer large, active Amphipods or insect larvae. Insome cases a single insect larva, two-thirds as long as the fishfilled the stomach.The young of most fish subsist on Entomostraca during theyounger stages, turning later to specialized and larger foods.In a fish of generalized feeding habits the time during which ittakes Entomostraca is known as the period of infancy, a laterperiod when midge larvas and other minute insect larvae areused is known as the period of youth, while the stage in whichthe usual food of the adult is taken is designated as the periodof maturity. The period of infancy seems to be entirely omitted95C. L. TURNER Vol. XXII, No. 3or to be passed over in specimens of less than 12 millimeters inlength. In this regard it resembles Etheostoma flabellare,which unlike most of the other darters captures large, activefood while still very small and if it takes Entomostraca at all itdoes so only in negligible quantities.The adult Millers Thumb is reported to be a voraciousfeeder and very destructive to other fish. It is interesting thatthe young resemble the adult in their ability and their willing-ness to capture large food animals which are proportionatelylarge even in 12 millimeter specimens. It is well adapted tofeeding upon large objects by its large terminal mouth.Table 'Length in mm.No. examinedArticles of diet:Midge larvaeMay fly larvaeAmphipodsPish remainsBottom debrisBeetle larvaeRound wormsFilamentous algaeFish eggsInsect eggsillustrating the food of young121100.13160.40.141100.1522.547.548.51.516333.33+51.66+15.of Cottus ictalops.17522.643.827.41.21.4.18520.54.18.6.2.19522.525.52.520528.7532.512.520.5.1.2521475.12.512.52231.66+81.66+16.66+Figures represent the percentage of the volume of the stomach contents.96

Notes on the Food Habits of Young of Cottus Ictalops (Millers Thumb)

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Notes on the Food Habits of Young of Cottus Ictalops (Millers Thumb)

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