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.
(Answer #1). The digestive system of flatworms is incomplete, not fully developed, yet more advanced than in any other simple livings, therefore, they complete their digestion by means of extracellular and intracellular activity.he complete digestive system of the flatworms consists of mouth, a tube similar to pharynx and the intestine that could be branched to enlarge the area of absoption of nutrients.