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.
Best Answer: Platyhelminthes consists of flat worms. They are dorsoventrally flattened. Have a gastrovascular cavity or no digestive system. No segments. Example) Planerian Nematoda is an unsegmented pseudocoelomate. No circulatory system. Consists of Roundworms. Annelia consists of segmented worms.