Nemertina is a phylum consisting mostly of free-living worms found in marine, freshwater, and soil habitats. Their common name ribbon worm refers to their flat bodies and the brilliant color patterns of many species. A long, sensitive anterior proboscis that is separate from the digestive tract characterizes nemertines. This unusual organ is branched in some species. The proboscis resides in a body cavity (rhynchocoel), from which the worm rapidly everts its proboscis as much as three times the length of its body. Muscular pressure on the fluid-filled proboscis chamber forces explosive eversion of the proboscis. So accurate is its aim that another common name for these worms is nemertine, based on the Greek term meaning the unerring one. Nemertines use the proboscis to explore the environment, to capture prey, to defend themselves, and for locomotion. Annoyed nemertines release their proboscises, which they then regenerate.