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.
These Flatworm creatures are hermaphroditic, which simply means that they have both male and female reproductive organs, and that they are able to produce both sexually and asexually. Now, the creatures of the Platyhelminthes phylum do not contain a body cavity nor a circulatory system. The circulatory system is very crucial for many organisms, but the species in this phylum do no have this specific system.