Oviposition and development of two intertidal snails, Littorina sitkana and Littorina scutulata

Abstract

At San Juan Island, Littorina scutulata spawns in the summer, releasing pelagic egg capsules with planktotrophic development, whereas Littorina sitkana spawns in the spring and autumn and lays benthic egg masses with lecithotrophic development. The larval development of each species is described and the chronological events from fertilization to hatching are tabulated.L. scutulata veligers hatch by a combination of mechanical and osmotic factors but L. sitkana juveniles utilize the foot and shell to rupture the capsular wall and capsular membrane. It was postulated that rows of tubercles on the larval shell of L. sitkana form an abrasive surface which facilitates hatching.Embryonic and juvenile growth was studied in L. sitkana. A rapid growth phase is observed when the young veliger begins to feed on the albumen.