1. Amphibians

2. Classification  Phylum Chordata  Subphylum Vertebrata  Class Amphibia  Order Urodela  Order Anura  Order Apoda

3. Origin of Amphibians  Amphibia means “double life”  ~4200 species  Believed to evolved from early lobe- finned fish over a million years ago.  Advantages to land over water  Large food supply  More shelter  No predators

4. General Characteristics  Endoskeleton  Ectothermic  Depend on water for reproduction  Must live around moist areas  Thin moist skin  Used for gas exchange  Undergo metamorphosis

5. General Characteristics  Respiration  Lungs, skin, and some gills  No Claws  Tetrapods- 4 legs  3-chambered heart  1 chamber recieves oxygenated blood from lungs, 1 receives deoxygenated blood from body, 3 rd chamber pumps blood to body/lungs

6. Reproduction  Separate sexes  Frogs and Toads- mostly external  Salamanders- mostly internal  Eggs laid- oviparity  Eggs develop inside without nourishment from mother- oviviparity  Eggs develop inside with nourishment from the mother- viviparity

7. Metamorphosis  Lifecycle  Fertilized egg (laid in water) hatch into tadpole  Tadpole grows into adult frog/toad  Fins are replaced with legs and 2- chambered heart is replaced with a 3- chambered heart.

9. Order Anura Frogs and Toads  No tail, neck, or scales  Vocal chords found in larynx  Males have pouches to increase volume of call, used for attracting mates  External Reproduction  Specialized limbs for jumping  Long sticky tongue attached to front of mouth for catching prey

10. Frogs and Toads  Adults have lungs  Adults are carnivorous, tadpoles are herbivores  Tympanic Membrane (eardrum) picks up vibrations from air and water.  Eyes on top of head allow them to stay submerged while seeing out of water  Nictitating membrane- keeps eyes moist

11. Frogs vs. Toads  Toads have  Shorter legs  Larger bodies  Thicker skin with prominent warts  Live primarily on land  Prefer dryer climates

12. Causes of Decline  5 reasons the populations of frogs and toads are declining  1. acid rain  2. water pollution  3. air pollution  4. use of pesticides  5. thinning ozone layer

13. Order Urodela Salamanders  Most abundant in North America  Have tails, no scales  4 equal limbs  Look like lizards, but with smooth, moist skin and no claws  Long slinder body  Some are completely Aquatic

14. Salamanders  Some breathe through skin while some have lungs  Carnivorous- feed on worms, small arthropods, and small mollusks  Internal Fertilization- Male deposits spermatophore on leaf and female recovers it and then lays fertilized eggs

16. Order Apoda Rare Caecilians  Long and Limbless  Look like worms, but have eyes covered by skin  Have small scales  Short or no tail  Some have small eyes, but most are totally blind  Found in tropical forests of S. America, Africa and SE Asia  Internal fertilization- some lay eggs, others have live birth

17. Caecilian