Form and Function

Each animal has physically adapted to its environment, as noted by Charles Darwin. But why do two species of fish often react quite differently within the same lake environment and why do the same species of fish often react quite differently in two different types of Iakes? Besides the biological factors, morphology and biokinetics also influence fish behavior. 

The morphology or body shape of fish has a great influence on how a particular species relates to an environment. The northern pike is highly specialized for acceleration. The salmonids take advantage of maximum thrust combined with minimum drag which make them highly capable cruisers, a necessity in open, deep water, or when fighting strong currents. The largemouth has a body shape which favors manoeuvrability at the expense of the ability to cruise or accelerate. Most fish are generalists, combining to some degree the abilities to cruise, accelerate, and manoeuvre.

The different ways in which fish feed illustrate the specialized biokinetic adaptations to specific environments. The jaws of the northern are well-armed with piercing and holding teeth, backed up by a well developed network of muscles - special equipment for high-speed attacks on quickly moving baitfish. In contrast, the white sucker's underslung vacuum-style mouth and grinding mandibles ideally suit it for bottom feeding on organic debris. The largemouth bass takes this ability further by literally creating a vacuum with its large, cartilaginous mouth to engulf a variety of food items which make up its diet.

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