Unlike the more primitive turbellarians, animals in this class lack cilia, and have a thick cuticle secreted by inner cells instead of a cellular epidermis. Like the Cestodans, they have suckers by which they attach themselves to a host, and much of their body is occupied by reproductive organs. Although one order is ectoparasitic, the endoparasitic varieties involved multiple hosts in their life 
Unlike the more primitive turbellarians, animals in this class lack cilia, and have a thick cuticle secreted by inner cells instead of a cellular epidermis. Like the Cestodans, they have suckers by which they attach themselves to a host, and much of their body is occupied by reproductive organs. Although one order is ectoparasitic, the endoparasitic varieties involved multiple hosts in their life cycle and pose major health risks to humans in areas with contaminated water. FTP, identify this class of flatworms whose most infamous member causes schistosomiasis.
Unlike the more primitive turbellarians, animals in this class lack cilia, and have a thick cuticle secreted by inner cells instead of a cellular epidermis.
trematoda or trematodes or flukes