● Metagenesis (alternation of generation) is observed in members of phylum Coelenterata (Cnidaria). ● Echinoderms are triploblastic and coelomate animals as true coelom is observed in them. ● Roundworms (Aschelminths) have organ system level of organization. ● Comb plates present in ctenophores help in locomotion. ● Water vascular system is seen in echinoderms, which helps in locomotion, capture and transport of food and respiration.