Final answer:
Eumetazoa includes animals with true differentiated tissues and body symmetry, divided into radial or bilateral symmetry, with bilaterally symmetrical animals typically being triploblastic and possessing a true or partial coelom.
Step-by-step explanation:
In contrast to Parazoa, which lack true differentiated tissues, the Eumetazoa includes all animals that have true tissues with distinct cellular and functional specialization and body symmetry. The Eumetazoa can be divided into creatures with radial symmetry, like cnidarians and ctenophores, and those with bilateral symmetry, encompassing the majority of animal species. Animals with bilateral symmetry typically possess three embryonic tissue layers, also known as being triploblastic, and may have an internal body cavity known as a coelom. This coelomic space can be lined completely by mesodermal tissue (true coelomates) or partially (pseudocoelomates), giving rise to various structures and systems within the organism.