Un-specialized cells, osculum, and no communication through the body

Cnidocytes, live in colonies

Mantle makes a shell, open circulatory system, and has a radulla

Body segments and appendages

Body segments and appendages

Molting, carapace, body segments, and appendages

Appendages, segments, chitin, pincers, and some have fangs with venom

Radial symmetry and has a water vascular system

Made of cartilage and has a barbed stinger

Made of bones and have an operculum

Have gills but lose them and they are the first land and water animal

"Cold blooded" and have scales

Live birth, hair, and produces milk

Wings, feathers, webbed feet