ABSTRACT
A comparative study of reproductive patterns was conducted using twelve abundant species of holothuroids in the San Juan Archipelago, Washington, USA. Modes of development include viviparity (one sp. of synaptid), external brooding (two dendrochirote spp.), lecithotrophy (seven spp. of dendrochirotes and one molpadid sp.), and planktotrophy (one aspidochirote sp.). Breeding seasons for the viviparous and externally brooding sea cucumbers begin in November and December, the eight lecithotrophic species spawn from December - May, while the single planktotroph has an extended reproductive season of April through September. The unique spawning behaviors exhibited by the different species appear adapted to their particular habitats to aid fertilization and dispersal. Extremes in fecundity and egg size range from 149 eggs of 1015µm diameter of a brooding species to nine million eggs of 206µm size produced by the planktotrophic species. Developmental stages were timed by monitoring cultures maintained at 11°C. Larval types include the auricularia, doliolaria, and a uniformly ciliated larva; the doliolaria may possess two, three, or five ciliary rings. Brooded embryos lack ciliation, metamorphose within the egg membrane, and hatch at the pentactula stage. Larval pelagic periods last 6 to 61 days. Most species’ size at metamorphosis is determined by egg size.
