Some species of phylum Nemertea are live in mud, There are 900 species of nemertea. nemertea are found in freshwater and terrestrial habitats as well. Most nemertea are carnivores, feed on worms, clams, they have commensalism relationships with some mollusks.

Some species have fish like characters of clams and crumbs. They are few millimeters and several kinds are centimeter in length. They have different coloures such as yellow, orange, red and green. They have Bilateral symmetry and have highly contractile body Epidermis is present with cilia and gland cells Body spaces are also present with a parenchyma, it may be gelatinous An eversible proboscis, is also present in it which lies free in a cavity) on upper side of alimentary canal It has Complete digestive system (mouth and anus is present Outer body layer is circular and inner layer is longitudinal with diagonal fibers Blood-vascular system have two or three longitudinal trunks Nervous system usually have four-lobed brain linked to paired longitudinal nerve trunks Excretory system also have two coiled canals, which are connected with flame cells Sex cells are separate with simple gonads; asexual and sexual reproduction present asexual reproduction by fragmentation .