Phylum Platyhelminthes

• They are commonly called as flatworms, they have dorso-ventrally flattened body.
• Habit - They are mostly endoparasites found in animals and human beings.
• Habitat - Fresh-water and salt water; terrestrial.
• Body symmetry - Flatworms are bilaterally symmetrical.
• Body wall - They are triploblastic animals.
• Coelomic cavity - They are acoelomate animals
• Level of organization - Organ level of organization.
• Digestive system - In flatworms digestive system is incomplete, that is the digestive cavity has a single opening.
• Parasitic flatworms possess hooks and suckers to hold on to the body of the host. Some forms absorb nutrition directly from the host, through their body surface.
• Osmoregulation and excretion is carried out by specialized cells cells flame cells.
• Sexes are not separate.
• Fertilization is internal and development is indirect, having many larval stages.
• Some members like Planaria possess high regeneration capacity.
• Examples: Taenia (tapeworm), Fasciola (liver fluke).