I. Vertebrates a. Chordates | i. Phylum Urochordata (Tunicates): 1. The deepest branching lineage of chordates. 2. Larva uses tail muscles and notochord to swim through water for a place to stay. 3. Goes through a radical metamorphosis in which most of its parts go away and the remaining parts rotate 90 degrees. ii. Phylum Cephalochordata (Lancelets) 1. Get name from bladelike shape 2. Passively sink to trap plankton and other suspended matter within their pharynx. 3. Muscles that are arranged as chevrons flex the notochord in undulations to thrust the body forward. 4. Possesses somites which are blocks of mesoderm that develop into muscle segments. b. Chordates | Craniates i. Class Myxini (Hagfishes) 1. Possess skull made of cartilage with no jaws or vertebrae. 2. Can produce liters of slime in less than a minute which coats the gills of an attacking fish sending it into retreat or suffocating it. c.
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