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.
In Worms. Flatworms have bilateral symmetry. Bilateral symmetry means the animal has symmetry across one plane (known as the sagittal plane, and directly down the centre of their body), â¦ which means one side of their body approximately mirrors the other side. Aaron McClellan.