84 ANIMAL AGGREGATIONS 



even though the animal selected for study belongs to what is usually 

 regarded as a non-social species. 



It is relatively easy, though sufficiently exciting to be called sport, 

 given the right body of water and the proper season and bait, to lift a 

 large-mouthed black bass from the water; but if one should under- 

 take to trace out all the interrelations from which the black bass has 

 suddenly been removed, he will have seen the whole complicated 

 mechanism of the aquatic life of the locality, both plant and animal, 

 of which the black bass forms a part. 



In the food of the black bass are to be found fishes of different 

 species at different ages of the individual, representing all the im- 

 portant orders of the fishes; insects in considerable number, especial- 

 ly the various water bugs and larvae of the May flies; fresh-water 

 crayfishes, shrimps, and a multitude of the small crustaceans called 

 Entomostraca, of many genera and species. 



Looking at the food of the fishes upon which the black bass feeds, 

 one finds that one of these eats mud, algae and Entomostraca, and 

 another takes nearly every animal substance in the water, including 

 mollusks and decomposing organic matter. The crayfishes are nearly 

 omnivorous; of the other Crustacea, some eat Entomostraca and 

 some algae and Protozoa. The insects eaten by the bass eat each 

 other, other insects, and Entomostraca. At only the second step, 

 therefore, do we find the black bass directly related to every class 

 of animals, many plants, and the decaying vegetal matter of the 

 water. 



Turning now to competitors, which are extremely numerous, we 

 find that all the young fishes, except the suckers, feed at first almost 

 wholly on Entomostraca, so that the young black bass finds himself 

 at the very beginning engaged in a scramble with almost all the 

 other fishes in the lake for food and, in fact, not only with the fishes 

 but with the insects and mollusks and larger crustaceans that also 

 live on these small entomostracans. The Mollusca are not in such 

 direct competition; but they do compete, since they feed upon the 

 microplankton which the Entomostraca themselves take as food. 



But the competitors of the bass are not limited to those which 

 take the same food, for predaceous fishes, turtles, water snakes, 



