I believe Echinoderms evolved first.
Cnidaria
Sponges, Cnidarians, Mollusks, and Echinoderms are not Arthropods.
Cnidarians and echinoderms
No, cnidarians do not have spicules. Spicules are small, needle-like structures made of calcium carbonate or silica that are found in some sponges and echinoderms for support and defense. Cnidarians, such as jellyfish and corals, have a different type of support structure called a mesoglea.
fish, mollusks, worms, crustaceans, echinoderms, sponges, tunicates and other cnidarians
Cnidarians are true radially symmetrical animals. They include jellyfish. Echinoderms (like starfish) also display radial symmetry. It is important to note that the larvae of echinoderms are bilaterally symmetrical and that Echinoderms evolved from a bilaterally symmetrical group.
By swimming using tentacles
Echinoderms (ex: starfish), cnidarians (ex: jellyfish) and and some vermiforms have longitudinal radial symmetry.
An invertebrate is an organism that lacks a backbone. The 6 groups of invertebrates are sponges, cnidarians, worms, mollusks, echinoderms and arthropods.
no, it is a vegetarian: D
CnidarianRadial symmetryNo body cavity other than gastrovascular cavitydiploblastic - 2 primary layers ( endoderm and ectoderm )Unique stinging cellsOne opening to digestive trackHydrostatic skeleton based on gastrovascular cavitymore primativeEchinodermRadial Symmetric adults, Bilateral larvaeDeuterostome developed coelomTriploblastic - 3 primary layers ( endoderm, ectoderm and mesoderm)Unique water vascular systemComplete digestive trackcalcareous endoskeleton, supplemented by water vascular systemMore derived