THE BIOLOGY OF A BROODING SEASTAR, LEPTASTERIAS TENERA, IN BLOCK ISLAND SOUND

¹ Smithsonian Oceanographic Sorting Center, Smithsonian Institution, Washington, D. C. 20560
² Biology Department, Brooklyn College, CUNY, Brooklyn, N. Y. 11210

Leptasterias tenera (Stimpson) was sampled from a muddy habitat, 28-37 m deep, dominated by tubicolous amphipods. The seastars were seldom aggregated and had mean densities of 3-8 individuals per m². L. tenera is holophagous, feeding primarily on small crustaceans which they capture with the pedicellariae and tube feet. Approximately half of the branched testes in mature males are degenerated or absent, but females usually have 10 lobate ovaries. Females initially brood embryos in their pyloric stomach and hold them externally during the latter half of the brooding period. The embryos are attached in cohesive masses by their elongate brachiolar appendages. L. tenera is slow-growing and iteroparous. The gonad and digestive caecum organ indices of L. tenera are not in phase with each other. Caecum index values indicate that females neither store more nutrient, nor utilize more reserves during the brooding period than males. Sexually mature males appear to have a higher rate of mortality than females. Thus, additional parameters must be examined to determine whether there is an energetic cost attributable to brooding adaptations in Leptasterias. It is possible that brooding specializations, small size, and slow growth rates typical for Leptasterias species are "cold adaptations" (sensu Clarke, 1980) rather than a coadaptive consequence of competition as suggested by Menge (1975) for Leptasterias hexactis.