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.
Specific animals that are part of this phylum are: Tapeworms, Flatworms, and also Planarians. So, these worm-like creatures are part of this phylum and do not contain a circulatory system.hese Flatworm creatures are hermaphroditic, which simply means that they have both male and female reproductive organs, and that they are able to produce both sexually and asexually. Now, the creatures of the Platyhelminthes phylum do not contain a body cavity nor a circulatory system.