Self-cleavage is also found among the higher multicellular organisms—namely, the Cnidaria (polyps, medus).
Real parasites are not numerous among the sponges and Cnidaria.
Flagellated epithelium is especially found in the Cnidaria and platodes; ciliated epithelium mostly in the vermalia and mollusca.
On the other hand, the Cnidaria develop into higher radial (star-shaped) persons, and the platodes into lower bilateral persons.
In this way is formed a ring of tentacles, the most characteristic organs of the Cnidaria.
I began with the consideration of the simplest sponges (olynthus) and Cnidaria (hydra).