Meeting Abstract

P3.13  Jan. 6  Teleplanic Larvae in Culture: 4.5 Years from Hatching to Metamorphosis STRATHMANN, M F; STRATHMANN, R R*; Univ. of Washington, Friday Harbor Labs; Univ. of Washington, Friday Harbor Labs rrstrath@u.washington.edu

Larvae of the NE Pacific snail Fusitriton oregonensis from field collected egg capsules were reared in the lab for 4.5 years from hatching to metamorphosis. The alga Rhodomonas was their primary food. Larval shell increased in width and length from 0.24 x 0.20 to 3.0 x 3.4 mm (greatest dimensions perpendicular and parallel to shell axis). Mean shell sizes increased slowly during their later years as larvae. The final protoconch width was similar to the 2.7 and 2.8 mm width on shells of field collected snails, indicating that size at metamorphosis was close to that in nature. Larvae had 4 narrow velar lobes. The total transverse spread across the velar lobes was as great as 2 cm. Fouling on shells of old larvae included diatoms and vorticellid and folliculinid ciliates. The larvae spent their last two years mostly on the bottom of the gently stirred glass jars with velar lobes extended. They did not metamorphose until the 11 survivors, out of the 4000 initially cultured, were presented with subtidal rocks and shells as substratum. Five metamorphosed juveniles survived and grew, the two females first reproducing 3.5 years after metamorphosis. This extraordinarily long larval period in culture may not reflect the natural duration but indicates the possibility of larval periods far longer than previously suspected. The larval duration exceeded the time from metamorphosis to first reproduction and greatly exceeded previous estimates of maximum time for larval transport in ocean currents.