Evolutionary patterns in tropical marine reef fish feeding

Abstract

The majority of tropical reef fishes are acanthopterygians. Most of them are percomorphs and thus are likely monophyletic. In accordance to modern systematics, the primitive types among the latter are large-mouthed suction feeders. Species from advanced families often have biting oral jaws with a reduced number and complexly shaped teeth. Mouth sizes decrease from the primitive towards the advanced reef fishes when ranked according to increasing family numbers (Nelson 1984). To create a functional resource axis, Randall's (1967) and Hobson's (1974) data on tropical reef fish feeding were re-interpreted by ranking food items from mobile to sessile prey. The primitive paracantho pterygian and acanthopterygian reef fishes are large-mouthed, suction-feeding predators on mobile prey. Most of the advanced, small-mouthed species are browsers and grazers, but often feed on mobile prey too. Obligatory specialists (monophagous and unable to switch) seem to be relatively rare among modern reef fishes. The trends stated above indicate a wealth of parallel developments in many advanced families of reef fishes towards small, often biting oral jaws. This parallelism may be the result of comparable regimes of selection pressures in reefs and of the need for newly evolved species to establish themselves within the already existing guilds.