| Notochords are the axial skeleton of invertebrate chordates, of agnathan fish, and of amphibian tadpoles. |
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| Above all, the appearance of diverse chordates and agnathans greatly expands our knowledge of the Cambrian explosion. |
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| Arthropods, chordates and annelids are the three segmented phyla in the animal kingdom. |
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| In those chordates which lack bone, muscles work against the notochord to move the animal. |
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| We chordates are deuterostomes, as are echinoderms, some marine worms called hemichordates, and the urochordates, or sea squirts. |
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| Comparison of their photoreceptive cells with those of the chordates corroborated such a phylogenetic position. |
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| In the animal kingdom there are many phyla, and the mammals come into a phylum called the chordates. |
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| Some DNA-based studies of evolution suggest that hemichordates are actually closer to echinoderms than to true chordates. |
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| Color changing or metachromatism or metachrosis is common in chordates and in vertebrates such as fish, amphibians and in some types of lizards. |
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| Janvier agrees that gills, and perhaps the external branchial skeleton, are primitive to the chordates. |
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| Most biologists are familiar with only a few of the approximately 40 extant animal phyla such as annelids, arthropods, molluscs, echinoderms and chordates. |
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| Into the early 1990s most researchers and evidence suggested that the deuterostomes were composed of chordates, hemichordates, echinoderms, chaetognaths, and lophophorates. |
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| Scenarios of pituitary evolution traditionally focused on the base of the chordates consistent with the exclusively chordate nature of the pituitary structure. |
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| Importantly, urchins act as the closest living relative to chordates and thus may shed light on the evolution of vertebrates. |
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| In addition, many students have never learned about the subphylum Urochordata and are under the mistaken impression that all chordates have a back bone. |
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