what type of symmetry and body cavity do platyhelminthes (flatworms) have?
Flatworms are considered acoelomate, since they have no body cavity, and roundworms are pseudocoelomate because they have a body cavity, but it is not derived from the splittiâ¦ng of the mesoderm tissue. Also, flatworms only have one opening in their digestive system unlike roundworms with two.
Platyhelminthes, or Flatworms, are the simplest kind of worms. There are about 20,000 species in this group. They are found in many places and can be free living or parasitic. A parasite lives off of another living thing called a host and can be harmful. One of the most known flatworms is the tapeworm. Also, Flatworms are found in marine and fresh water. Type of Skeleton A flatworm has no skeleton, but has tiny bristles called cilia that help it move at least two layers of muscles under its skin. It has three cell layers called the endoderm, the mesoderm and the ectoderm. They also have the beginnings of a head region. They are a phylum of triploblastic acoelomate invertebrate animals. The word platyhelminthes comes from the Greek words 'platy' meaning flat and 'helmins' meaning worm. Their bodies are soft, unsegmented, dorsoventrally flattened with bilateral symmetry and resemble ribbons.