Population density and predators of Ophiacantha fidelis (Koehler, 1930) (Echinodermata : Ophiuroidea) on the continental slope of Tasmania

Densities of the brittle star O. fidelis at a site on the upper continental slope (420-580 m) off eastern Tasmania, Australia, were calculated from underwater photographs. Their beds covered 61% of the substratum, with a mean density of 348 animals m-2 (52.2 g m-2). The starfish Mediaster australiensis, which was restricted to O. fidelis beds, had a mean density of 0.09 animals m-2 (5.5 g m-2). Gut analyses of trawled M. australiensis confirmed that they are predators of 0. fidelis, as were several common benthic fish species.