Hirudinaria (Indian cattle leech) is sanguivorous (blood sucking) animal with 2 suckers-one oral and another anal suckers. It is an ectoparasite on cattle and humans and lives in ponds, stream, rice field etc. They secrete an anticoagulant hirudin from their salivary glands, which causes blood clotting.
Nereis (the sand worm) is gregarous nocturnal carnivorous with separate sexes. The body is metamerically segmented. It has three parts head, trunk and pygidium. Its sexual stage is known as heteronereis.
Tapeworm (Taenia solium) is an endoparasite in human intestine, who consume pork as their food. It is digenetic with elongated ribbon shaped body. It formly gets attached to the wall of intestine with hooks and suckers.
Earthworm (Pheretima posthuma) has a cylindrical body. The body is divisible into 100−200 segments by circular grooves. It is terrestrial or freshwater and varies in nutrition.