1. Vertebrate Diversity

2. Phylum Chordata Bilateral Deuterostomes 4 characteristics
Dorsal, hollow nerve cord
Central nervous system
Notochord
Supports nerve cord, reduced in many vertebrates
Pharyngeal slits
Filter feeding, gills, parts of ear
Post-anal tail

3. Chordates Lancelets Tunicates
Muscle structure similar to fish in chevron shape
Tunicates
Only larval stage has chordate characteristics
9 hox genes instead of 13 like vertebrates
Research on genetic control of brain and nerve formation

4. Craniates Head with brain, eyes, nerves Characteristics
Neural crest becomes teeth and some nerves
Pharyngeal slits become gills
Muscular digestive system to support higher metabolism

5. Craniates Hagfishes Brain and partial skull No jaws or vertebrae
Marine scavangers
Slime glands to avoid being eaten

7. Vertebrates Backbone made of vertebrae Lampreys- no jaws
Parasites of fish
Problems for Great Lakes

8. Gnathostomes Have jaws Aquatic species have lateral line systems
Sensitive to changes in water pressure
Fossil gnathostomes: placoderms
Armored fish
Dunkleosteus: 10m long

9. Chondrichthyes Sharks and rays
Reduced calcification of bones is derived
Denser than water
Oil filled liver to reduce density
Suspension feeders or active predators

10. Chondrichthyes
Rays
Bottoms dwellers
Predators
Enhanced pectoral fin

11. Chondrichthyes Sharks Acute senses for predatory lifestyle
Detect electric fields
No eardrums, entire body receives sounds waves

12. Osteichthyes “bony fish” Paraphyletic without tetrapods
For now, just the aquatic variety
Operculum covering gills
Swim bladder
Evolved from lungs
Scales

13. Bony Fish: Ray Fins Most of fish Fins supported by bony rays
Evolved in freshwater and then moved to the sea
Some still make this transition during life

14. Bony Fish: Lobe Fins
Pectoral and pelvis fins have rod shaped bone surrounded by muscle.
Used muscular fins to walk on land in swampy areas
Only three lineages remain

15. Bony Fish: Lobe Fins Coelacanths Lungfishes
Thought to be extinct until 1999
Lungfishes
Only six species
Gills and lungs to gulp air
When ponds dry up, can estivate in the mud
Tetrapods (next section of notes)

16. Tetrapods
Gnathostomes with 4 limbs

17. Amphibians Salamanders, frogs and caecilians “double life”
But not in salamanders and caecilians
Damp habitats
Exchange gas across skin
External fertilization
Some carry fertilized eggs on back

20. Amniotes Tetrapods with a terrestrially adapted egg Amniotic egg
Amnion- fluid filled cavity to protect against physical shock
Chorion- exchange gases
Yolk sac- stockpile of nutrients
Allantois- waste products
Covered in shell or remains in mother’s body
Rib cage to enhance breathing through lungs

22. Reptiles: Traits Scales containing keratin Shelled eggs
Internal fertilization
Ectothermic
Derive body heat from surroundings
EXCEPT birds
Diapsids

23. Reptile Diversity
Lepidosaurs
Tuataras
Squamates
Snakes
Lizards

24. Reptiles: Turtles Distinctive because of shield
Fused to the ribs and vertebrae
May be most closely related to crocodiles

25. Alligators and Crocodiles
Appeared during Triassic
Some were as big as 12m long

26. Reptiles: Birds Most characters are derived for function in flying
Wings and feathers
Efficient lungs
Acute vision
Larger brain
Lighter bones

27. Mammals
Amniotes that have hair and produce milk

28. Mammals: Diversity Monotremes Marsupials Eutherians
Australia and New Guinea
Platypus and echidnas
Lay eggs
Marsupials
Give birth to live young early in development
Offspring continue to develop in pouch
Eutherians
Offspring are born well developed