MASS LABORATORY CULTURE AND ASSOCIATED STUDIES OF THE LONG-TERM PLANKTOTROPHIC LARVAE OF BOONEA BISUTURALIS (OPISTHOBRANCHIA: PYRAMIDELLIDAE)

The first successful mass culture technique for long-term planktotrophic opisthobranch larvae has been developed and used to rear&nbsp;<em>Boonea bisurturalis</em> (Pyramidellidae) to metamorphosis in the laboratory. To prevent entrapent of veligers by surface tension, free air is excluded from the culture jars by flexible plastic lids. At water changes, larvae are collected behind a screen clamped between two funnels incorporated into a siphon tube. <em>Boonea bisuturalis&nbsp;</em>larvae in cultures of multiple parentage show a neary linear increase in mean shell length with hime until competence for metamorphosis is approached, when the rate of linear growth decreases. Considerable variation in the growth rate of individual larvae is found within cultures. The stage in organogenesis indicated by appearance of eye pigment is not accurately predictable from shell length. Changes in shell shape during development are illustrated by drawings. In settlement experiments, two gastropod and one polychaete species induced metamorphosis of these larvae. A fully effective narcotization technique for gastropod veligers has been developed, and relaxed&nbsp;<em>Boonea bisuturalis</em> larvae of different developmenta stages have been examined using scanning electron microscopy.