evolutionIn both sharks and teleost fishes, undulation of the body gen-erates forward locomotion. However, it is notable that while tailmorphology differs greatly between these two groups of fishes, inboth cases the tail still acts as a major locomotor control surface tomanipulate fluid dynamics involved in swimming, albeit in differ-ent ways. But why should the tail of fishes have evolved a great dealof morphological differentiation amongst species when the trunkmorphology has not specialized to the same degree? The answerto this question may lie in the functional attributes inherent in agiven tail morphology which might have been selected for due toparticular performance advantages.