1. CHORDATES and VERTEBRATES
Or you got a lot of nerve... or is it backbone?

2. The phylum Chordata includes three subphyla, the vertebrates and two phyla of invertebrates, the urochordates and the cephalochordates.
Fig. 34.1

3. FOUR CHARACTERISTICS
These chordate characteristics are a notochord; a dorsal, hollow nerve cord; pharyngeal slits; and a muscular, postanal tail.

4. Four anatomical features characterize the phylum Chordata
1. The notochord, present in all chordate embryos, is a longitudinal, flexible rod located between the digestive tube and the nerve cord.
2. The dorsal, hollow nerve cord develops in the vertebrate embryo from a plate of ectoderm that rolls into a tube dorsal to the notochord.

5. 3. Pharyngeal gill slits connect the pharynx, just posterior to the mouth, to the outside of the animal.
4. Most chordates have a muscular tail extending posterior to the anus.

6. Assignment Chordate
Provide details for each of the four anatomical features of the chordates.
Describe the two chordates that are invertebrates
Describe the evolution of chordates

7. Vertebrates
Neural crest, pronounced cephalization, a vertebral column, and a closed circulatory system characterize the subphylum Vertebrata.
Why are these four features important to vertebrates?

8. Fig. 34.7

9. Finally
At each evolutionary step describe the changes to vertebrates to help explain the diversification we see today.