1. Chordates (Chap 27)

2. Kingdom: Animalia Phylum: Chordata (evolved ~535 mya) All chordates have the following features at some point in their life (may only be present in the embryo): pharyngeal slits - a series of openings that connect the inside of the throat to the outside of the "neck". These are often, but not always, used as gills. dorsal nerve cord - a bundle of nerve fibers which runs down the "back". It connects the brain with the lateral muscles and other organs.

3. notochord - cartilaginous rod running underneath, and supporting, the nerve cord. post-anal tail - an extension of the body past the anal opening.

4. Subphylum: Vertebrata (evolved ~ 500mya) Characteristics have vertebral columns (backbones) brain enclosed in a cranium ventral heart gills or lungs two-- pairs of limbs, eyes, kidneys, sexes

5. 7 Living Classes of Vertebrates 1. Agnatha marine animals lack jaws and paired fins skeletons of cartilage ~ 75 sp. -- hagfish and lampreys

6. 2. Chondrichthyes fishes with skeletons of cartilage skin is placoid scales– miniature teeth embedded in the skin ~ 700 sp. -- sharks, skates and rays

7. 3. Osteichthyes “bony fishes” have a swim bladder have an operculum, a flap on each side of the fish that covers the gills over 29,000 species

8. 4. Amphibia most develop and reproduce in water have primitive lungs moist skin for gas exchange ~ 5700 sp. -- frogs, salamanders…

9. 5. Reptilia scales well-developed lungs most are terrestrial internal fertilization a leathery amniotic egg- embryo surrounded by a fluid-filled sac and membranes ~ 6500 sp. -- turtles, snakes, lizards…

10. 6. Aves light and strong skeleton beak, no teeth feathers large yolked, hard-shelled eggs enlarged sternum where flight muscles can attach ~ 9000 sp.

11. 7. Mammals