THE TOXOGLOSSAN PROBOSCIS: STRUCTURE AND FUNCTION

The structure of the proboscis and anterior alimentary systemis described and reviewed in the three families (Conidae, Terebridae,Turridae) of the Conoidea (=Toxoglossa). A number of proboscisforms are shown, characterized by the presence of a permanentrhynchodeum, modified alimentary system and a venom apparatus.Despite the diversity of prey types in the Conidae (polychaetes,molluscs and fish) they have a uniform proboscis structure witha long buccal tube and functional buccal and venom apparati.This homogeneity is not present in the Turridae and the Terebridaewhich show a variety of proboscis structures. Terebrids feedonly on polychaetes or hemichordates but appear to have threeprimary feeding modes based on significant difference in thestructure and function of the buccal tube and associated buccalorgans. The greatest variety of proboscis type is found in thediverse Turridae which feed mainly on polychaetes, but includesipunculans, gastropods and nemerteans in their diet.