Exclusively marine, radially symmetrical, diploblastic organisms with tissue level of organisation are included under
Exclusively marine, radially symmetrical, diploblastic organisms with tissue level of organisation are included under Ctenophora. Porifera includes animals with cellular level of organisation and some of them live in freshwater (e.g., Spongilla). Some cnidarians (e.g., Hydra) live in freshwater. Echinoderms are triploblastic with organ-system level of organisation.