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.
The Platyhelminthes are the simplest animals that are bilaterally symmetrical and formally triploblastic (composed of three fundamental cell layers).http://www.tolweb.org/Bilateria/2459. Four Clades or Classes of Platyhelminthes: Turbellaria-The Free-Living Flatworms.omplex, through incomplete gut in free living forms, absent in some parasitic forms. The following organ systems are present. Integumentary system :The epidermis is composed of a wholly or partially ciliated, syncytial or cellular epithelium, with gland cells and sensory nerve endings.