Ammonium and free amino acid uptake by a deep-sea mussel (Bathymodiolus sp., undescribed) containing methanotrophic bacterial symbionts

The morphology of the lophophore and mouth was measured for freshly collected colonies of seven common bryozoan reef species at three sites along the central Caribbean coast of Panamá during the dry season, from the end of December 1988 through May 1989. Characters measured or scored include the number of tentacles, circumference of the lophophore, abanal and anal tentacle length, abanal and anal tentacle spacing, and perimeter of the mouth. Taxa studied include three species each of Stylophoma Levinsen, and Steginoporella (Smitt), and one species of Trematooecia Osburn. Individuals were collected from both continental and offshore fringing reefs from depths of 1 to>30 m. Terrestrial runoff from heavy tropical rains, sedimentation, and sea exposure vary greatly between sites. Congeneric species showed small but consistent differences in lophophore size, but little or no difference in spacing of tentacles or perimeter of the mouth. This suggests that closely related species feed on similarly sized particles despite their overall differences in zooidal size. Lopophore morphology also varied intraspecifically between reefs, particularly in the length of the tentacles and spacing between tentacles. Patterns of variation were similar for all species, which implies that species shift their diets in similar directions between the different reefs. The combination of these patterns suggests that niche diversification in feeding does not occur among congeneric species in the cheilostomes examined.