1. Phylum chordata Invertebrate chordates (no backbones) vertebrate chordates (have backbones)

2. All chordates have the following: • Notochord: • Flexible dorsal supporting rod • Usually replaced by a backbone as embryo develops • Hollow dorsal nerve cord • As opposed to the ventral nerve in other animals • Pharyngeal (throat) slits • In aquatic chordates, these gills are slits • In terrestrial chordates, these slits disappear early in embryonic development

3. Invertebrate chordates • Tunicates and lancelets • Not many of these but they are of great evolutionary interest • Possible link between vertebrates and all other animals

4. Vertebrate chordates • Fish (3 classes) • Amphibians • Reptiles • Birds • Mammals

5. Vertebrates (subphylum vertebrata) • Characteristics: • Endoskeleton • Vertebral column (“backbone”) • Closed circulatory system • Ventral heart • Usually four appendages

7. Temperature control • All vertebrates must keep their body temperatures within a certain range. There are 2 ways of doing this • Ectotherms: change behavior in response to temperature fluctuations • Lack effective insulation, have low metabolic rates, are fish, amphibians, reptiles • Endotherms: rely on heat generated by their bodies (and some behavioral strategies) • They have insulation, high metabolic rates, birds, mammals and possible dinosaurs

8. Fish • Aquatic vertebrates with scales, fins and pharyngeal gills • Classes: • Agnatha: primitive jawless fish that are parasitic or scavegers, includes lampreys and hagfish • Condricthyes: ancient group of mostly predatory cartilaginous fish (skeleton entirely cartilage), includes sharks, skates and rays • Osteichthyes: “regular” fish with a bony skeleton. 97% of all fish are in this class

9. Amphibians • Vertebrates that are aquatic as larvae and terrestrial as adults • Have moist skin, lack scales and claws, and adults breath with skin and lungs • Smallest vertebrate class (4000 species) • It has three orders: • Frogs and toads (order ANURA) • Salamanders and newts (order CAUDATA) • Legless amphibians (order APODA)

10. Reptiles • Vertebrates with adaptations that enable them to live entirely on land • Have lungs that are more efficient than amphibians, scaly skin to prevent drying out, amniotic egg with shell, yolk and several protective membranes • 4 orders • Snakes and lizards • Crocodilians • Turtles, tortoises + terrapins • Tuataras (last species of an order common in time of dinosaurs)

11. Birds • Reptile like vertebrates with the following modifications: • Feathers • Front limbs modified into wings • Hind limbs for perching/walking • Birds are as successful as mammals in the modern world. (live almost in all habitats) • Many orders: songbirds, waterfowl, raptors, seabirds, penguins and flightless birds