Nemerteans, also known as ribbon worms or proboscis worms, are graceful and often spectacularly colorful marine predators related to annelids, molluscs and other Lophotrochozoan animals.

The phylum Nemertea (= Rhynchocoela) contains about 1250 described species which occur intertidally, subtidally and at great depths in all of the worlds oceans.

Nemerteans are unsegmented and characterized by a unique eversible proboscis, which in some species is armed with venomous stylets. Proboscis is used to attack and subdue prey (e.g. annelids and crustaceans).

The name is derived from that of Nemertes, a greek sea goddess, one of the  50 sisters nereids, daughters of gods Nereus and Doris. The name means “wise, unerring”.