Lineus

Lineus is a genus of marine annelid worms belonging to the phylum Nemertea, commonly known as ribbon worms. These unsegmented worms are characterized by their long, slender, and often brightly colored bodies. They are found in a wide range of marine environments, from shallow intertidal zones to the deep sea, inhabiting various substrates such as sand, mud, and rocky areas.

The most distinctive feature of Lineus worms is their proboscis, a muscular, eversible tube used for capturing prey. This proboscis can be extended rapidly and forcefully, often entangling or paralyzing small invertebrates like crustaceans, mollusks, and other worms. Many species are carnivorous, while some may feed on detritus.

Lineus worms possess a complete digestive system and a closed circulatory system. They reproduce sexually, with most species being dioecious, releasing eggs and sperm into the water column. Larval stages are planktonic before settling to the benthos. Some species can also reproduce asexually through fragmentation. Their ecological role includes predation and serving as a food source for other marine animals. Their slimy mucus coating helps protect them and aids in locomotion.