Bocas Species Database

Habitat: Pier pilings, rock reef, and coral reef habitats with its associated sponges.   Distribution: Caribbean   Natural History Notes: Individuals are occasionally found outside of sponges, but most are endocommensals of sponges such as 'Agelas spp., Verongia lacunosa, and Neofibularia nolitangere. Some of these sponges are toxic and avoided by sponge-eating predators, to the advantage of the brittle stars. The species suspension feeds at night, extending pairs of arms from sponge oscula. The eggs produced by the species are small (0.07 mm diameter), suggesting planktotrophic larval development.   Depth: 2-618 m, but usually less than 73 m.   Characteristics: O. quinqueradia is the largest Caribbean Ophiactis species, reaching 13 mm in disk diameter with arms 100 mm long. The species is exclusively five-armed. There are usually six arm spines. The middle spines are longest, flattened, with a broad, spinulose tip; the dorsal spines are shorter, rounded, and more pointed; the most ventral spine is smallest. Disk coloration is dark reddish brown, purplish brown, or black, variegated with gray and white. The arms are banded with gray, black, tan, or brown.