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.
Three types of worms with different body types will be explored in this lesson: 1  Flatworms, which have ribbon-like bodies with no body cavity. 2  Roundworms, which have a body cavity but no segments. 3  Segmented worms, which have both a body cavity and segmented bodies.haracteristics of Flatworms. There are specific differences between the flatworms and the roundworms. 1  Unlike the flatworms, the roundworms have a body cavity with internal organs. 2  A roundworm has a complete digestive system, which includes both a mouth and an anus.