Reproduction , Spawning and Development of the Starfish Patiriella exigua (Lamarck) (Asteroidea : Asterinidae) and Some Comparisons with P. calcar (Lamarck)

Abstract

P. exigua adults are mature throughout the year. The species can breed in any month of the year, though spawning is most active in the late winter and spring. P. calcar has a definite breeding season in the late spring and summer. P. exigua lays an egg mass through oral gonopores. The 400-�m eggs develop directly, through a yolky brachiolaria stage to a juvenile star, before leaving the egg mass at 22-23 days. P. calcar, with eggs of similar size laid through oral gonopores, has a planktonic lecithotrophic larva. The development of P. exigua is compared with that of other yolky asteroid embryos. Modes of development in the genus Patiriella are discussed.