Cestodes, more commonly referred to as tapeworms, are a class of parasitic flatworms belonging to the phylum Platyhelminthes. They are parasites of the digestive tract of vertebrates, with over one thousand described species. Humans often are exposed to them through the consumption of undercooked meat or through poor hygiene and living conditions.
Cestode bodies are flat and ribbon like. They possess a neck, which is thought to be immortal, and a body composed of a series of successive proglottids, which are collectively referred to as the strobila. The proglottids are capable of independent reproduction, leading some biologists to conclude that a single worm should not be considered to be a single organism. Cestodes are also characteried by their scolex, which is a structure at the head of the tapeworm that is used to attatch to the intestine of the definitive host. While the scolex is structured differently in different cestode species, it is typically composed of bothria, tentacles that function as suction cups, or a combination of hooks and suckers.