Cestoda

Cestoda is a class of parasitic worms in the flatworm phylum (Platyhelminthes). Most of the species—and the best-known—are those in the subclass Eucestoda; they are ribbon-like worms as adults, commonly known as tapeworms. Their bodies consist of many similar units known as proglottids—essentially packages of eggs which are regularly shed into the environment to infect other organisms. Species of the other subclass, Cestodaria, are mainly fish-infecting parasites.

Eucestoda is the larger of the two subclasses of flatworms in the class Cestoda (the other subclass being Cestodaria) whose members are commonly known as tapeworms. Larvae have six posterior hooks on the scolex (head), in contrast to the ten-hooked Cestodaria. All tapeworms are endoparasites of vertebrates, living in the digestive tract or related ducts. Examples are the pork tapeworm (Taenia solium) with a human definitive host, and pigs as the secondary host, and Moniezia expansa, the definitive hosts of which are ruminants.

Cestodaria is one of two subclasses of the class Cestoda. The Cestodaria subclass is made up of Amphilinidea and Gyrocotylidea. The larvae have ten hooks on the posterior end.

REDIRECT Amphilinidae

thumb|right| Drawing of Cysticerus cellulosae: Left one from the pig showing an invaginated scolex. Right one from human intestine showing the evaginated scolex. Cysticercus (pl. cysticerci) is a scientific name given to the young tapeworms (larvae) belonging to the genus Taenia. It is a small, sac-like vesicle resembling a bladder; hence, it is also known as bladder worm. It is filled with fluid, in which the main body of the larva, called scolex (which will eventually form the head of the tapeworm), resides. It normally develops from the eggs, which are ingested by the intermediate hosts, su

Gyrocotylidea is an order of Cestoda (tapeworms). Members of this order are parasites of vertebrates, living in the coelom (the body cavity). Gyrocotylidea are a subspecies of the tapeworm that is mainly a parasite of fishes and turtles. They do not have a gut, thus being classified with Cestodes.

thumb|right|Plerocerci of Callitetrarhynchus gracilis in the body cavity of the fish [[Scomberomorus commerson]]

Bothriocephalus is a genus of flatworms belonging to the family Bothriocephalidae.

Triaenophoridae is a family of flatworms belonging to the order Bothriocephalidea.

thumb|General description of the egg and oncosphere of Echinococcus spp.

The procercoid is the second larval stage of some tapeworms, which typically develops inside of copepods following their ingestion of the coracidium parasite structure that contains the larval oncosphere. The flatworm in this stage is not enclosed in a protective cyst, but is infectious to the next intermediate host. Procercoids resemble their adult forms in pathways of energy metabolism. They are basically anaerobic, lacking a complete Krebs cycle, and rely on glycolysis.

A cysticercoid is the larval stage of certain tapeworms, similar in appearance to a cysticercus, but having the scolex filling completely the enclosing cyst. In tapeworm infections, cysticercoids can be seen in free form as well as enclosed by cysts in biological tissues such as the intestinal mucosa. Also referred to as metacestodes, they produce proteins enabling them to invade and to survive in the host. It is typically associated with cyclophyllid tapeworms that have an invertebrate intermediate host, but can appear in humans during the autoinfective cycle of Hymenolepis nana.

Bothriocephalidea is an order of Cestoda (tapeworms). Members of this order are gut parasites of vertebrates.

genus of worms

Amphilinidae is a family of parasitic flatworms of the phylum Platyhelminthes. It is the only family in the monotypic order Amphilinidea. Amphilinids are Cestodes, yet differ from true tapeworms (Eucestoda) as their bodies are unsegmented and not divided into proglottids. "Amphilinids are large worms which have a flattened leaf-like body. Only 8 amphilinid species are known." "The adults are hermaphroditic. A muscular proboscis is located at the anterior end, and is sometimes very weakly developed or absent." They live in the body cavities of freshwater turtles and teleost fish as adults, and

Cathetocephalidea is an order of flatworms belonging to the class Cestoda.