I. Chordates

A. ALL CHORDATES HAVE:

Notochord (stiff rod along dorsal aspect of embryo)

Tubular dorsal nerve cord

3. Slits in pharynx

4. Embryonic Tail

B. Chordate Classification

Subphyla: Tunicates (Invertebrate chordates)

Subphyla: Lancelets (the almost fish)

Subphyla: Vertebrates (encased nerve cord)

C. Evolutionary Trends

Circulatory System: Open vs. Closed and Single-loop vs. Double-loop

Feeding: Filter feeder to developed jaws.

Breathing: Simple diffusion to repiratory organs.

II. The fishes

A. 3 Remaining Divisions:

Jawless(lampreys)

Cartilagenous (sharks, rays)

Bony (most fish in world)

B. Key Characteristics

1. Encased nerve cord

2. 2-chambered heart/Single Loop

3. Modified lung = Swim bladder (regulates buoyancy) in bony fish

4. Gills for gas exchange

III. Amphibians

Examples: Frogs,salamanders, toads

Two life stages: aquatic and terrestrial.

Must return to water for reproduction.

Three-chambered heart (single loop)

Respire through the skin (exhale).

IV. Reptiles

A. Examples: Lizard, Turtle

B. Adapted to life on Land:

1. 3 (+) chambered heart

2. Dry scales for skin (conserve H20).

Possible due to efficient lungs.

4. Kidneys excrete urea, not ammonia.

5. Internal fertilization.

6. Ectotherms (cold-blooded).

Thermal Regulation

Cold-blooded, or

Ectotherm (heat from environment)

Warm-blooded, or

Endotherm (heat

from within)

V. Aves (Birds)

Characteristics:

1. Feathers (modified scales)

2. 4-chambered heart (Double Loop)

3. Endotherms

4. Often hollow bones

5. Urea-based waste

B. Archeoptryx: Bird?

Willo: Dinosaur Heart

C. Birth in Amniotes

1. The amniotic egg has three layers:

a. Amnion: Membrane holding fluid

around embryo.

b. Allantois: Membrane for gas exchange

and waste removal (surrounds yolk).

c. Chorion: Outer most membrane;

functions in gas exchange.

2. Shell on outside of egg

VI. Mammals

Characteristics:

1. Mammary gland (all)

2. Hair

3. 4-chambered, double loop circulation

4. Endotherms

5. Extreme development of Brain

Class Mammalia (con’t)

B. Three Orders:

1. Monotremes (egg-laying mammals)

2. Marsupials (young develop in pouch)

3. Eutherians/Placental Mammals

(humans)

VII. (if you want to keep numbering) Geologic Ages

Paleozoic (Ancient Age): No/Little Oxygen; Inverts and Fish

Mesozoic (Middle Age): Dinosaurs, Ferns, Few Mammals

Cenozoic (Current Age): Age of mammals (and insects)