The evolution of different body plans in animals has led to a wide diversity of species. For example, in Cnidaria (which includes jellyfish and corals) we see a radically different body plan compared to insects or birds. What significant evolutionary development is exhibited by insects and birds that is not present in Cnidaria? The development of bilateral symmetry and cephalization. The development of radial symmetry. The development of a calcified exoskeleton. The development of tentacles for capturing prey. 666