9/20/2023 0 Comments Flat worm eggsCestodes (tapeworms) and trematodes (flukes) have complex life-cycles, with mature stages that live as parasites in the digestive systems of fish or land vertebrates, and intermediate stages that infest secondary hosts. Free-living flatworms are mostly predators, and live in water or in shaded, humid terrestrial environments, such as leaf litter. In traditional medicinal texts, Platyhelminthes are divided into Turbellaria, which are mostly non- parasitic animals such as planarians, and three entirely parasitic groups: Cestoda, Trematoda and Monogenea however, since the turbellarians have since been proven not to be monophyletic, this classification is now deprecated. The digestive cavity has only one opening for both ingestion (intake of nutrients) and egestion (removal of undigested wastes) as a result, the food cannot be processed continuously. Unlike other bilaterians, they are acoelomates (having no body cavity), and have no specialised circulatory and respiratory organs, which restricts them to having flattened shapes that allow oxygen and nutrients to pass through their bodies by diffusion. The flatworms, flat worms, Platyhelminthes, or platyhelminths (from the Greek πλατύ, platy, meaning "flat" and ἕλμινς (root: ἑλμινθ-), helminth-, meaning "worm") are a phylum of relatively simple bilaterian, unsegmented, soft-bodied invertebrates. Possible Cambrian, Ordovician and Devonian records īedford's flatworm, Pseudobiceros bedfordi
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