In geophysics the refraction or reflection of seismic waves is used for research into the structure of the Earth's interior, and man-made vibrations are often generated to investigate shallow, subsurface structures.
Flatworms are considered acoelomate, since they have no body cavity, and roundworms are pseudocoelomate because they have a body cavity, but it is not derived from the splittiâ¦ng of the mesoderm tissue. Also, flatworms only have one opening in their digestive system unlike roundworms with two.
Explain the basic body plan of members of the phylum Platyhelminthes. Identify representatives of the classes Turbellaria, Trematoda, and Cestoda. Compare and contrast the anatomy and morphology of free-living and parisitic flatworms. Describe the symmetry of this group. Platyhelminthes is a phylum composed of three classes of flatworms. The class Turbellaria (planarians) is free-living, while the remaining classes including the Trematoda (flukes) and Cestoda (tapeworms) are parisitic. Members of the phylum Platyhelminthes are dorsoventrally flattened.