DEVELOPMENTAL TYPES OF SHALLOW-WATER ASTEROIDS OF MCMURDO SOUND, ANTARCTICA

The mode of development was ascertained for 14 of the 16 species of sea stars known to occur in shallow waters of McMurdo Sound, Antarctica (77°51′S; 166°40′E). The species were collected between September 1984 and December 1985. Females of three species, Odontaster validus, O. meridionalis and Porania antarctica, spawn small to moderate eggs (0.17 to 0.55 mm), have a high fecundity, and produce feeding larvae. Females of an undescribed Porania species spawn a few eggs (150 to 310) that are 0.55 mm in diameter and develop into demersal non-feeding larvae. Females of Diplasterias brucei and Notasterias armata produce a few (<300) large eggs (2.8 to 3.5 mm) and brood their young. Females of the remaining eight species have moderate fecundity and produce pelagic non-feeding larvae, as determined from egg type (buoyant, 0.54 to 1.28 mm diam) and direct observations of spawning and development. The high incidence (11 out of 14 species; 79%) of non-feeding development is consistent with predictions that environmental conditions in high-latitude regions are unfavorable for planktotrophic development. Nonetheless, most of the species surveyed (11 out of 14) had pelagic larvae, which contradicts inferences of unusual selection for benthic development in the Antarctic. © 1990 Springer-Verlag.