Abstract

A coelodendrid phaeodarian with features diagnostic for several subfamilies is described from individual living specimens collected during mesopelagic submersible operations in the Bahamas. Scanning and transmission electron microscopy reveal features of the functional morphology of the organism which adapt it to its mesopelagic existence. There was no evidence of gelatinous material in the specimens examined, but these radiolaria maintained neutral buoyancy in vitro. There was an elaborate network of rhizopodial strands extending over the surfaces of the verticillate branches of the distal regions of the skeleton. These radiolaria readily accepted certain types of prey in the laboratory and remains of metazoan prey were found in recently collected organisms.