captaculum

…head with slender tentacles, the captacula, that serve as sensory and food-catching organs. The anterior end is usually buried in the sea bottom. The posterior end admits water for respiration and discharges wastes. Tusk shells feed upon such small organisms as protozoans of the order Forminifera and young bivalves. Sexes…

…the filamentous head tentacles (captacula). Except for the carnivorous septibranch anomalodermata, all bivalves are ciliary suspension feeders, using food-sorting organs near the mouth (labial palps) and respiratory gills modified to assist in feeding (ctenidia). Found in marine and fresh water, most bivalves burrow into sediments to depths of 10,700…