1. VERTEBRATES Kingdom – ANIMALIA Phylum – CHORDATA (means “cord”) Subphylum – VERTEBRATA (means “jointed backbone”) I.Evolution of Vertebrates: Invertebrate Ancestors Amphibians Fish Reptiles Birds Mammals

2. II.Characteristics of ALL Vertebrates A.Hollow nerve cord B.Notochord – in embryos; in most vertebrates is replaced by a backbone that protects nerve cord & allowsfor greater flexibility C.Postanal Tail – extension of vertebrae in some vertebrates

3. D.Bilateral Symmetry E.Endoskeleton F.Coelom – a body cavity G.Closed Circulatory System – blood flows through vessels to/from heart H.Complex Brain, Sense Organs & Efficient Respiratory Systems

4. Chapter 28.1-2 – Fishes and Amphibians I.Characteristics of ALL Fish A.Gills – respiratory structures made up of feathery gill filaments w/ tiny blood vessels 1.Fish takes in water thru mouth 2.water w/ dissolved O 2 (not from H2O) passes countercurrent to blood flow in the gill’s capillaries

5. B.2-chambered Heart: slow blood flow 1.1 chamber receives deoxygenated blood from the fish’s tissues 2.Other chamber pumps blood to capillaries in gills, where O 2 is picked up & CO 2 is dropped off

6. C.Sexual Reproduction – w/ egg & sperm 1.can be released directly into water 2.can be deposited on plants D.Paired Fins – (ray or lobe) fan-shaped membranes made of bone for balance, swimming, & steering 1.Lobed fins foreshadowed the development of limbs for movement on land & wings for flying (p. 831)

7. E.Developed Sensory Systems 1.Lateral Line – cartilage & bony fish have this fluid-filled canal line to sense vibration changes in the environment 2.Eyes – allow fish to see objects & differences in light and dark 3.Sense of Smell – detect chemicals

8. Lateral line system Swim/Air bladder Scales Gills Fins Kidney Urinary bladder Reproductive organ Stomach Intestine Liver Heart

9. II.Diversity of Fish (more species of fish than all other vertebrates combined) A.Superclass AGNATHA – “without jaws”  Class MYXINI – hagfish  Class CEPHALASPIDOMORPHI – lampreys 1.Jawless, cartilage skeleton, no scales, internal fertilization 2. Lampreys use a sucker to attach & drink dying fish’s blood, teeth scrape flesh away

10. B.Class CHONDRICHTHYES – “cartilage”  sharks, skates, rays 1.Predators living on/near ocean floor 2.Jaws, cartilage skeleton, scales, paired fins, internal fertilization a.Skates deposit fertilized eggs on ocean floor (mermaid purse) b.Some sharks & rays carry young inside their bodies

11. C.Class OSTEICHTHYES – means “bony”  walleye, sturgeon, bass, trout, perch, etc. 1.Jaws, bony skeleton, scales, paired fins 2.Air/Swim bladder – depth is changed by adjusting amount of gas 3.Most do external fertilization called “spawning”