Differences in Larval Settlement Site between Generalist and Specialist of Aeolid Nudibranchs

Abstract

The preys of three flabellinid nudibranchs and the distribution of their pediveliger larvae were investigated to reveal the relation between the width of dietary spectrum and the larval recruitment site. Hundreds of pediveligers were found in total from the field. Flabellina amabilis and Flabellina sp. were specialists consuming exclusively one hydroid species, while Flabellina athadona was a generalist eating five hydroid species. Not only in the specialists but in the generalist, the pediveligers were associated with their adult diet hydroids, although there was a hydroid species on which the larvae of the generalist could hardly succeed to settle. As to microdistribution of pediveligers on the hydroids, there was a significant difference between the specialists and the generalist; pediveligers of F. amabilis and F. sp. were mostly found to directly adhere to the naked hydranths, while those of F. athadona were found away from the naked hydranths. The causes of these phenomena are discussed.