Phylum NEMERTEA – nemerteans, nemertines
Small phylum, 200 - 300+ spp.
Rhynchocoel, proboscis, some with proboscis armature, a stylet and accessory stylets. Some produce toxins. Commonly with separate sexes. Colorful, long worms (up to 100 ' long specimens of Lineus ruber). Important role in mudflat food webs.
Malacobdella grossa – "oyster leech," common symbiont in oysters and clams. Lives in mantle cavity, eats mucus from host. Not considered parasitic, some data suggests it may almost be mutually beneficial to host. Direct life cycle, do not transfer between hosts.
Carcinonemertes – egg predators of crabs and lobsters. Small size, reduced proboscis armature. C. carcinophila on the blue crab. Stylet for egg puncture. Direct life cycle, but cues for settlement are not well known. Worms associated with catastrophic declines in Dungeness crab stock off N. California, red king crab stocks in fjord areas and Kodiak Island off Alaksa. High intensity infections resemble castration. Sexual transmission in C. errans, transfer at molt on all species.
Symbiotic forms occur in tunicates, in hermit crab shells, etc.