Abstract
The larval preference of Bugula neritina for settlement to each constituent of primary film, such as detrital particles, attaching bacteria and attaching diatoms which had been coated on a glass slide by immersing in the sea and in a closed circulating aquarium was studied through a choice test. Two hundred larvae were put in a chamber where six not film-coated and six film-coated glass slides were stuck on the inner side of the Iid of the chamber. The settlement index on film-coated glass slides was defined as the difference between the numbers of larvae which settled on the film-coated and not film-coated surfaces.
The glass slide coated with the primary film was preferable for the settlement of the larvae to the not film-coated glass slide. The attaching diatom showed a quite similar pattern of increase to that of the settlement index. The attaching diatoms on the surface of the glass slide was the most attractive for the settlement of the larva.
