Nemertine Toxins

Abstract

Nemertines are a generally toxic phylum of carnivorous worms which are rarely observed by marine biologists as they are generally of small size (0.5-3 cm is a common length) and usually hide under rocks or burrow in sand and mud. Over 800 species have been described by taxonomists (Gibson, 1972). Most inhabit the intertidal zone, although others occur in a variety of other habitats including land, freshwater and the open sea. Being soft-bodied and unable to rapidly escape from predators, they produce integumentary toxins which serve as a chemical defense against predators (Kern, 1971, 1985, 1988a). The phylum is roughly divided into two large groups, the hoplonemertines which possess a proboscis stylet (mineralized armature), and the anoplans, which lack a stylet. The hoplonemertine stylet is used to puncture the skin of the prey (usually annelids or crustaceans) at multiple sites, thus facilitating entry of toxins into the circulatory system of the organism The relative scarcity of nemertines in most marine habitats makes them relatively difficult to collect. Another problem is species identification, as the external morphologies of some species are so similar that the preparation of tissue sections for histological examination may be necessary. Nonetheless, this phylum represents an unusually rich source of toxins, including alkaloids, peptides, and proteins, most still awaiting investigation.