Platyhelminths are mainly known as flatworms. These flatworms are bilaterally symmetrical and are triploblastic. Platyhelminths are also acoelomates and participate in gas exchange by diffusion in the integumentary layer. Platyhelminths are subcategorized into two classes: Trematoda and Cestoidea. Clonorchis sinensis, a trematode parasite, and Echinococcus granulosus, a cestoidean parasite, are similar in that they are both Platyhelminthes, but these parasites differ in terms of their life cycle and ability to cause infection in humans. Clonorchis sinensis belongs to the class Trematoda. All trematodes are parasitic. Most trematodes have complex life cycles normally having two or more hosts, the first host almost always being the mollusk. “Selection of the second intermediate host is less host specific since cercariae are stimulated to swim by shadows and movement” (Eckroad). Echinococcus granulosus belongs to the class Cestoidea. All cestodes are endoparasites requiring at least two hosts. The life cycle of Echinococcus granulosus includes dogs and other dogs as its definition...