Members of the Phylum Nemertea are called nemerteans or ribbon worms. These aquatic animals are typically found in marine environments, though a few species are found in fresh water or moist soil.

True to their name, ribbon worms typically have threadlike or ribbon-shaped bodies. They are usually less than 20 cm long, but some species are several meters in length.

Ribbon worms are carnivorous and all species have a long, muscular proboscis that is used to grasp prey. They feed primarily on annelids and other small invertebrates.