BIOLOGICAL FACTORS AFFECTING LARVAL GROWTH IN THE NUDIBRANCH MOLLUSK HERMISSENDA-CRASSICORNIS (ESCHSCHOLTZ, 1831)

The nudibranch mollusc Hermissenda crassicornis is used as a biomedica l model for studying learning and memory. It is an eurytrophic benthic species with long-term, planktotrophic larvae, and it has been cultur ed in our laboratory for several years. This paper reports the effects of some dietary factors on H. crassicornis larvae that were investiga ted in order to establish the conditions for optimal larval growth. Of the several treatments tested densities of 1-4 larvae ml(-1), a diet of Isochrysis galbana Parke and Rhodomonas salina (Wislouch) Butcher a t a 1:1 mixture, and an algal density of 10-25 x 10(3) cells ml(-1) yi elded the largest, healthiest larvae, that underwent metamorphosis. Bo th diet quantity and quality, as well as larval density, had an effect on larval growth and metamorphosis of Hermissenda crassicornis in the laboratory. (C) 1997 Elsevier Science B.V.