The mesoderm of adult round worms lines the inside of the body cavity but not around the gut. You may use a diagram but it must be labeled and explained. Name one phylum for each type of organism. Below is a cross section of a chordate embryo . Label the three structures indicated by the lines which you would likely see in such a cross section.
Urochordates are a subphylum containing tunicates.
The adults are a sessile form of a free swimming larval stage. Energy is used for survival and reproduction. A sessile life style in which food comes to you does not require cephalization, or structures for movement. Individuals that put energy into reproduction and not the maintenance of unused structures will have more offspring. These structures will be lost in the population.