Larval Development and Metamorphosis of the Sea Star Luidia foliolata (Echinodermata : Asteroidea)

Abstract

Spawning of Luidia foliolata in Barkley Sound, British Columbia, Canada, occurs in spring. Ova are transparent and about 150μm in diameter. The first cleavage occurs approximately 3hr after fertilization at ca. 10℃. The embryo develops into a bipinnaria after a wrinkled blastula stage. Metamorphosis takes place about 4 mo after fertilization, without the larva's passing through a brachiolaria stage. The full-grown bipinnaria is 2.5mm long and has five pairs of bipinnaria arms. At metamorphosis the larval part is absorbed into the asteroid rudiment. Juveniles are about 730μm in diameter. They have five arms, each bearing two pairs of tube-feet. The present observations show that L. foliolata undergoes a non-brachiolarian type of development, as do all species of Luidia previously studied.