Meeting Abstract
Gill rakers of ray-finned fishes are bony structures that extend anteriorly off the gill arches into the buccopharyngeal cavity. Filter-feeding fishes have highly elongate and filamentous rakers to filter plankton during ram and suspension feeding. However, many ray-finned fishes that do not filter feed still retain small and widely spaced rakers that are assumed to play a role in protecting gill tissue during feeding. To understand how the morphology of non-filtration rakers evolves in response to diet, we studied a group of closely related fishes, the sculpins (superfamily Cottoidea). Sculpins have a wide range of diets, although they are all primarily suction feeders. We examined 12 sculpin species from the Pacific Northwest using scanning electron microscopy to take measurements of rakers. We quantified evolutionary correlations of raker morphometrics, head measurements, and previously published diet data using phylogenetically independent contrasts and phylogenetically corrected ANOVAs. We found that premaxillary length, raker diameter, and raker spacing were larger in species that primarily ate prey that required manipulation. This is one of the first studies to directly correlate raker size to diet in non-filter-feeding fishes, and the relationship between raker diameter and prey type implies that wider rakers are used to protect the gill tissue during prey manipulation.
