Commonly known as flatworms, Platyhelminthes are very simple invertebrates with flattened bodies. They have no body cavity, circulatory, or respiratory systems. this restricts their shape. Nutrients and other vital materials pass though the skin through diffusion. They have a simple digestive tract with only one opening for ingestion and egestion.
The muscular system present in flatworms is comprised of layers of circular, longitudinal, and diagonal muscles close to the epidermis, and separate muscles consisting of transverse, and longitudinal fibers passing through the connective tissue. Because of this, Platyhelminthes can willingly expand and contract, extensively.
Most flatworms are either pests or parasites. causing disease in humans and other animals. However they can be beneficial in population reduction of other pests. Click one of the following links to see more details of three