Secernenteans (seck-uhr-NEHN-shuns) are land-dwelling parasites of plants and animals. Parasites (PAIR-uh-sites) are animals or plants that live on or in other animals or plants, or hosts, without helping them and usually harming them. Secernenteans can be microscopic to several feet long. The body of secernenteans consists of a flexible cylinder with a pointed tail and a blunt head. A flexible but tough covering with a system of crosswise grooves from head to tail protects the insides of secernenteans. Lengthwise ridges run along most of the body. Most secernenteans have a hard, sharp spear on the head. They use muscles to move the spear in and out to puncture their host's cells and empty the contents.
Animal Life ResourceJellyfish, Sponges, and Other Simple AnimalsSecernenteans: Secernentea - Physical Characteristics, Behavior And Reproduction, Secernenteans And People, Canine Heartworm (dirofilaria Immitis): Species Accounts - GEOGRAPHIC RANGE, HABITAT, DIET, CONSERVATION STATUS