Phylum Chordates

Chorates have 3 basic characteristics, number one being a dorsal notochord just under the nerve cord. number two being a dorsal hallow nerve cord that like above the notochord. Lastly being pharyngeal pouches that become gills in fishes and amphibian larvae.
Invertebrate chordates are ocean floor dwellers with a thick walled squat sack with incurrent and excurrent siphons. also, they have numerous gill slits for filter feeding. as for larvae they have three chordate traits, ancestors may have matures in larval form to become primitive fish.