Eucestoda

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.

==Body structure== Adult Eucestoda have a white-opaque dorso-ventrally flattened appearance, and are elongated, ranging in length from a few millimeters (about ") to 25 meters (80'). Almost all members, except members of the orders Caryophyllidea and Spathebothriidea, are polyzoic with repeated sets of reproductive organs down the body length, and almost all members, except members of the order Dioecocestidae, are protandral hermaphrodites. Most except caryophyllideans consist of a few to 4000 proglottids (segments) that show a characteristic body differentiation pattern into scolex (head), neck, and strobila.