Elaborates Class Trematoda and Monogenea - Flukes?

Members of this Class are commonly known as the tapeworms. They resemble a long flat tape, or ribbon, and are parasitic, living in the intestinal tracts of humans and other animals. Tapeworms have many specialized features that are characteristic of the highly evolved parasitic lifestyle. They lack a digestive tract since they absorbed digested food through their skin.

Tapeworms have an anterior organ called the scolex, which attaches itself to the host by means of suckers and hooks. The main body of a tapeworm consists of a long chain of flattened segments called proglottids. Each proglottid segment contains mostly male and female reproductive structures. Fertilization of eggs by sperm can occur between two different individual tapeworms; sperm from one proglottid may fertilize eggs from another proglottid on the same individual; or sperm may fertilize eggs from the same proglottid. The chain of proglottids may exceed lengths of 10 meters, with the oldest, most mature segments toward the end.

The fertilized eggs, or zygotes, start to develop within the proglottids. The proglottids can either break away or burst open in this mature state. Zygotes are then expelled with the feces from the host animal and can be deposited on various surfaces or in water, where they are ingested by another animal.