A NEW DISTRIBUTION RECORD AND NOTES ON THE BIOLOGY OF THE BRITTLE STAR OPHIACTIS SIMPLEX (ECHINODERMATA: OPHIUROIDEA) IN TEXAS

摘要

Brittle stars (Echinodermata: Ophiuroidea) are a common component of marine communities and often make up a significant portion of the biomass. Identification, however, can be problematic, particularly in the small fissiparous species. Fissiparity, asexual reproduction in which an individual divides in two and regenerates missing parts, occurs in 34 of the 2,000 species of brittle star (Emson & Wilkie 1980). One of these is Ophiactis simplex, an eastern Pacific species, with distribution from the Channel Islands to Panama and the Galapagos Islands (Neilsen 1932; Lonhart & Tupen 2001). Like other fissiparous brittle stars most specimens have six arms and are asymmetrical, with three long arms and three shorter arms. However, individuals with five and seven arms are not uncommon; the author has collected one with nine arms. One of the distinguishing characteristics of this species is the red tube feet. The red color is due to the presence of hemoglobin containing coelomocytes (RBCs) present in the water vascular system (Christensen 1999).