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.
CLASSIFICATION OF PLATYHELMINTHES. (Girish Chandra). PHYLUM PLATYHELMINTHES. Commonly known as flat worms, they are acoelomate, triploblastic and bilaterally symmetrical animals which have no skeleton, respiratory and circulatory systems.Alimentary canal when present is in blind sac plan.lass TURBELLARIA (Dugesia; Bipalium; Leptoplana; Notoplana). They are free living eddy worms, with flattened body and mouth located on the ventral side. Suckers are absent and epidermal cells are multiciliated.