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.
Introduction. Platyhelminthes, or flatworms, are considered by many to be ancestral to most of the metazoans that were to follow and for the first time we see the development of the final germ layer, the mesoderm, with its potential to form muscles and other structures.ut, unlike the other animals that are to follow, in flatworms the mesoderm remains as a solid mass of tissue without a coelom and the advantages that this adaptation could have provided to the group are lost. This probably explains why most of today's flatworms are parasitic rather than free living.