In both sharks and teleost fishes, undulation of the body generates
forward locomotion. However, it is notable that while tail
morphology differs greatly between these two groups of fishes, in
both cases the tail still acts as a major locomotor control surface to
manipulate fluid dynamics involved in swimming, albeit in different
ways. But why should the tail of fishes have evolved a great deal
of morphological differentiation amongst species when the trunk
morphology has not specialized to the same degree? The answer
to this question may lie in the functional attributes inherent in a
given tail morphology which might have been selected for due to
particular performance advantages