| We chordates are deuterostomes, as are echinoderms, some marine worms called hemichordates, and the urochordates, or sea squirts. |
| Arthropods, chordates and annelids are the three segmented phyla in the animal kingdom. |
| Janvier agrees that gills, and perhaps the external branchial skeleton, are primitive to the chordates. |
| In those chordates which lack bone, muscles work against the notochord to move the animal. |
| Notochords are the axial skeleton of invertebrate chordates, of agnathan fish, and of amphibian tadpoles. |
| Comparison of their photoreceptive cells with those of the chordates corroborated such a phylogenetic position. |
