ABSTRACT
The teleost (whole + bone) ‘shes are not as menacing as sharks, but their numbers attest to their success. They are ‘erce competitors if not ‘erce predators, which many of them are. Lanham (1962, p. 77) pointed out that teleosts have radiated into niches formerly used by more primitive ‘shes and have expanded their ranges into habitats that may not have been occupied previously:
Teleosts were present by the late Triassic (ca. 220 mya), and they are the most numerous and diversi‘ed vertebrates. There are at least 26,840 teleost species, and they constitute 96% of all living ‘shes (Nelson 2006). Common to all teleosts is a newly derived homocercal tail that appears more symmetrical on the outside than the heterocercal tail of their ancestors (Figure 6.1), but it is actually asymmetrical on the inside due to the presence of new skeletal bones (i.e., uroneurals) that act as supports to stiffen the caudal ‘n. Other features include further development of the gas bladder into a highly ef‘cient hydrostatic organ changes in bones of the mouth, and development of a branchial pump for feeding and other purposes.
