A combination of factors is likely causing the decline of blue spruce trees throughout Michigan. Posted on March 7, 2011 by Dennis Fulbright, Michigan State University Extension, Department of Plant Pathology, and Jill OâDonnell, Michigan State University Extension.
Flatworms lack a respiratory or circulatory system; these functions take place by absorption through the body wall. Nonparasitic forms have a simple, incomplete gut; even this is lacking in many parasitic species. Movement in some flatworms is controlled by longitudinal, circular, and oblique layers of muscle.
All flatworms have a soft body and a triangle-shaped head. They also have eye-spots on top of their heads which can see light. Flatworms are not closely related to most other worms, such as earthworms. Bodies are flat instead of round, and they do not have segments. Flatworms spend most of their time on the bottom, especially since they can't swim. They release sticky mucus (a lot like slugs and snails) which they glide on top of.