1. Chapters 30-32 Biology – Miller • Levine
The Chordates
Chapters 30-32
Biology – Miller • Levine

2. Chordates Phylum Chordata
Includes two invertebrate subphyla: lancelets and tunicates
Subphylum Vertebrata

3. Chordate Characteristics
Dorsal, hollow nerve cord – the brain and spinal cord
Notochord – flexible, longitudinal rod located between the digestive tract and the nerve cord
Pharyngeal pouches – gill structures in the pharynx
Post-anal tail – tail to the rear of the anus

4. Chordate Characteristics
The characteristics are not always visible in the adult form, but are always present in the embryo

5. Vertebrates
Subphylum that includes mammals, birds, reptiles, amphibians and the various classes of fishes
Unique features include cranium and backbone

6. Fishes

7. Agnathans Jawless fish Class Myxini (hagfishes)
Class Cephalaspidomorphi (lampreys)

8. Class Chondrichthyes Cartilaginous fishes Include sharks and rays
Have a flexible skeleton made of cartilage
Lateral line system – row of sensory organs running along each side of the body, detects minor vibrations

9. Class Chondrichthyes

10. Class Osteichthyes Bony fishes (trout and goldfish)
Also have a lateral line system
Operculum – protective flap that covers the gills
Swim bladder – gas-filled sac that keeps them buoyant

11. Class Osteichthyes
Most are ray-finned fishes – fins supported by thin, flexible rays
Lungfishes – must surface to gulp air into their lungs
Lobe-finned fishes – fins are supported by stout bones

12. Amphibians

13. Class Amphibia Frogs and salamanders
Exhibit a mixture of aquatic & terrestrial adaptations
Need water to reproduce
Depend on their moist skin to supplement lung function in exchanging gases

14. Class Amphibia First vertebrates to colonize land
Tetrapods (“four legs”) – terrestrial vertebrates (amphibians, reptiles, birds & mammals)

15. Reptiles

16. Class Reptilia Snakes, lizards, turtles, crocodiles, and alligators
Have many additional adaptations for living on land
Water-proofed scales to prevent dehydration
Amniotic egg – water-containing egg enclosed in a shell

17. Class Reptilia Ectotherms – warms itself by absorbing external heat
Can survive on less than 10% of the calories required by mammals
Mesozoic era – “age of reptiles” – the time of the dinosaurs

18. Birds

19. Class Aves Birds Reptilian features – scales on legs, amniotic egg
Almost all species are able to fly

20. Class Aves Adaptations for flight: Light, hollow bone
Absence of some internal organs
Are toothless
Endotherms – maintain temperature using metabolic heat
Wings – strong muscles, feathers

21. Mammals

22. Class Mammalia Probably evolved from reptiles
Most are terrestrial, some are aquatic (dolphins, whales), some can fly (bats)
Two unique features: hair and mammary glands
Are endotherms
Have a fluid filled amniotic sac

23. Three Major Groups Monotremes – egg-laying mammals (platypus)
Marsupials – pouched mammals (kangaroo)
Eutherians – placental mammals
Make up almost 95% of mammals
Marsupials and Eutherians both have a placenta which joins the embryo to the mother and provides nutrients to the embryo

24. Class Mammalia

25. Primates Order that includes monkeys, apes & humans
Early primates were small, arboreal (tree-dwelling) mammals
Limber shoulder joints, dexterous hands, eyes close together on face, excellent hand-eye coordination

26. Primates Divided into two main groups:
Prosimians (lemurs)
Anthropoids (monkeys, apes & humans)
Humans are most closely related to apes