Parameter Tree:
EARTH SCIENCE > BIOLOGICAL CLASSIFICATION > ANIMALS/INVERTEBRATES > FLATWORMS/FLUKES/TAPEWORMS

Definition:
Flatworms have a dorsoventrally flattened, simple triploblastic body lacking
a coelom, anus and blood vascular system. 


Reference:
Burn, David M. Animal World. 1980. Octopus Books Ltd. London.