Trematoda is a class of parasitic flatworms commonly known as flukes. They are characterized by their leaf-like shape and lack of a body cavity. Trematodes typically have complex life cycles that involve multiple hosts, including snails and various vertebrates, such as fish and mammals. These organisms are known for causing diseases in their hosts, including schistosomiasis, which affects millions of people worldwide. Trematodes attach to their hosts using specialized structures called suckers, allowing them to feed on blood, tissues, or other bodily fluids. Their ability to adapt to different environments makes them successful parasites.