WHITE SUCKER 
173 
FOOD AND THE FEEDING HABITS OF THE WHITE SUCKER 
With respect to their food, fishes may be divided into several groups. For 
example, we have plankton feeders, mud feeders, insectivorous species, fish eaters, 
mollusk eaters, and herbivorous species. Probably very few fishes confine their 
diet to one of these types of food, yet the classification is useful and may be applied 
in a broad sense. The factor that usually causes fishes to deviate from one type 
of food is their size. Obviously very small fishes must subsist upon still smaller 
organisms, so we are not surprised to learn that microorganisms form the early 
food of most species. 
Some fishes pass through more than two stages in their feeding activities. The 
bass, for example, is a plankton feeder at first; later it pursues such Crustacea as 
the water shrimps and also insects, and as an adult it feeds largely upon smaller 
fishes, frogs, and crawfish. 
The case of the sucker is peculiar in that a new factor — namely, the position of 
its mouth — enters in to alter its range of feeding. As its mouth changes from a 
terminal to an inferior position, the fish must alter its diet, losing those forms that 
swim or float and sucking in the fauna of the stream bottom. This, together with 
its wide range of taste, makes it almost omnivorous, and it is difficult to classify 
it according to the system mentioned above. While, of the various groups listed, we 
would be obliged to consider the sucker principally insectivorous, yet in an interest- 
ing way many insects escape it entirely. On the other hand, it does not exclude 
entirely any of the types of food upon which other fishes subsist. 
REVIEW OF THE LITERATURE 
Examination of the stomach contents of the white sucker has been made by 
Forbes (1890), Hankinson (1908), Reighard (1915 and 1920), Baker (1916), and 
Pearse (1918). Two or three facts are at once evident in reviewing this work. The 
number reported upon by each author ranges from 5 to 42, which seems a small 
number upon which to draw conclusions in the case of a fish of such varied feeding 
habits. Again, in most cases the size of the specimens does not cover a wide range 
from any one locality, which is necessary in giving a picture of the biological relation- 
ships of the organism throughout its life; and the time of year frequently is not 
mentioned, yet we know that age, season, and available food all influence the selec- 
tion of items in the diet of fishes. 
It is striking to note how much disagreement exists in the accounts referred to 
above. Forbes and Baker report mollusks as forming 42 per cent and 30 per cent, 
respectively, of the food eaten. Pearse mentions no mollusks, while Hankinson 
notes their presence but gives no percentages. Again, while Pearse gives chiro- 
nomid larvae as forming 40 per cent of the food, Forbes reports but 3 per cent; and 
while Baker. (1916) found “mud and plant remains” making up 49 per cent (3 
adults), Pearse finds “algae and silt” composing but 6.6 per cent. Similar variance 
could be shown in the reports on Protozoa, May-fly nymphs, rotifers, etc. The 
observations of the authors in question probably are reliable, so we must assume 
that the disagreement is due to the difference in place, age, and season. 
