Bilaterally symmetrical, metamerically segmented animals with a closed circulatory system are included under the phylum
Annelids are bilaterally symmetrical, metamerically segmented animals with a closed circulatory system.
Arthropods have an open circulatory system
Molluscs are unsegmented and most of them have an open circulatory system.
Echinoderms are unsegmented and are radially symmetrical in the adult stage.