MULTIPLE-MODES OF ASEXUAL REPRODUCTION BY TROPICAL AND SUBTROPICAL SEA STAR LARVAE - AN UNUSUAL ADAPTATION FOR GENET DISPERSAL AND SURVIVAL

Sea star larvae (Echinodermata: Asteroidea), collected from the subtro pical Northwest Atlantic Ocean, exhibited three distinct modes of asex ual reproduction. A number of different bipinnariae and brachiolariae reproduced by paratomous cloning of the posterolateral arms. This morp hogenesis was identical to that of larvae assignable to the genus Luid ia. A second mode of asexual reproduction involves the autotomization of an anterior portion of the preoral lobe. Primary larvae with preora l lobes of varying sizes and free-swimming preoral lobes of various st ages of morphological development were simultaneously collected. The f ree-swimming preoral lobes developed complete digestive systems and ul timately assumed the form of typical bipinnaria larvae. Asexual reprod uction by larvae may also take the form of budding. The released indiv idual is either a blastula- or gastrula-stage embryo. Subsequent devel opment to a bipinnaria-stage secondary larva, with the possible except ion of coelom formation, appears to occur through the events associate d with normal larval development. These diverse methods of asexual pro pagation provide a common mechanism to increase the length of larval l ife and amplify the number of individuals. Thus asexual reproduction b y larvae should increase the likelihood of genet representation in the next generation.