Planktonic juveniles of the estuarine brittlestar Ophiophragmus filograneus (Echinodermata: Ophiuroidea) and their implications for method of reproduction and recruitment.

The Florida seagrass brittlestar, Ophiophi·agmus flograneus, is endeinic to shallow estuarine bays and lagoons of Florida, where it is exposed to variations in salinity that are beyond the ambient range for most echinoderms, Whereas the physiological basis for its salinity tolerance has not been studied, the species seems to have other aspects of its biology that help with its estuarine life. The full spectrum of its life-history pattern is unknown. Still, the presence of planktonic juveniles in an ichthyoplankton study of the Indian River Lagoon System indicates that it can be dispersed even if it lacks a pluteus lana Occurrence in tlie plankton ranges from spring through fall, although variations in timing and density differ among basins of the Indian River Lagoon System. Planktonic juveniles are smaller than those reported from benthic samples, although some demonstrate the unusual pattern of arm growth reported for new bentl-tic recruits of this species. The presence of two long non-adjacent arms of the larger specimens might serve to gi·asp blades of seagrass upon settlement to the benthos. [ABSTRACT FROM AUTHOR]