JACOBS, M.W.; Friday Harbor Laboratories, University of Washington: Pelagic Juvenile Ascidians? Dispersal and Reproductive Ecology of Herdmania momus and other Solitary Ascidian Species.

Solitary ascidians produce small, short-lived, non-feeding larvae which function primarily in habitat selection and dispersal. Because all adult ascidians are sessile, dispersal in these common invasive species is usually thought to be limited by larval lifespan (or in some instances rafting of adults). I show that the tropical stolidobranch ascidian Herdmania momus (formerly H. curvata) is capable of detaching and dispersing after metamorphosis. 79% of these �pelagic juveniles� successfully reattached within 24 hours when offered appropriate settlement conditions. Furthermore, attachment in both H. momus and Phallusia julinea, another solitary tropical species, can be delayed until hours, days, or even weeks after metamorphosis. Evidence from these and other species suggests that this potential to extend dispersal beyond larval life may be widespread in the ascidians, and has serious implications for our understanding of ecology and invasibility of the ascidiacea.