Acting Fishy: Evolutionary Perspectives On Fish Behavior

Essay by GrimslayUniversity, Bachelor'sA+, May 2005

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The fishes are the most numerous and diverse of the vertebrate groups, stemming from a long and branched line of ancient ancestry. Though they account for more than half of the world's total vertebrate species, they have essentially retained the same anatomical plan for 450 million years (Maisey, 1996). What accounts for the stamina of these living fossils? During their evolutionary history, fishes have given rise to a vast diversity of forms, not merely to survive but also to compete, they have colonized an extraordinary range of habitats, and their sheer numbers are nearly enough to ensure their survival (Whitehead 1975). Alongside these marks of success are the patterns of behavior that have evolved to help the various species cope with environmental, ecological, and individual strains that threaten to impede on their survival. Of the most significant categories of behavior are migratory behavior, schooling behavior, feeding behavior, aggressive behavior, resting behavior, reproductive behavior, and communication.

Migration is the mass movement of fish from one region to another. A migration can be from saltwater to saltwater, freshwater to freshwater, saltwater to freshwater, vice versa, or hopping back and forth from one to the other. One means by which fish increase their numbers is to spawn in an area that their young are likely to thrive in. Though the energy investment is high, some fish will swim for weeks or even months to reach a suitable spawning ground for the development of larva, which often, is the same as their "home" area that they can recognize by its distinctive odor, orientation to the magnetic fields and water gradients (Moyle, Cech 1996). This behavior, in turn, creates a separation of life history stages in that, once hatched, the currents will carry the young to favorable feeding areas, and once they are active swimmers...



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