1. Amphibian- “Double Life” - Water and land
Chapter 19-Amphibians
Amphibian- “Double Life”
- Water and land

2. Amphibian Characteristics
1st true tetrapod vertebrates
Bony skeletons with four limbs
Exceptions: Caecilians (limbless) and Sirens (forelimbs only)
Many w/webbed feet
Thin moist skin; no scales
Breathe w/ lungs (Internal, bag-like organ that exchanges oxygen and carbon dioxide with the air and blood)
Exception: Lungless salamanders
Larvae- gills
Cutaneous respiration- “Skin breathing”
Supplement oxygen intake w/ moist skin
Limited by body size

3. Double-Loop Circulation

4. Amphibian Characteristics
Partially divided heart:
Atrium separated into left and right sides by septum, ventricle is not
Right side sends oxygen-poor blood to lungs
Left side send oxygen-rich blood to organs
Double-loop circulation:
Two large veins (pulmonary veins) return oxygen-rich blood from lungs to heart
Blood pumped to tissues at higher pressure than fish
Systemic circulation- Blood flow to the body

5. Class Amphibia Order Anura- Frogs and toads
Order Urodela (Caudata) – Salamanders, sirens, newts, waterdogs, mudpuppies
Order Gymnophiona (Apoda)- Caecilians

6. Class Amphibia

7. Order Anura- Frogs and Toads
Anura- without a tail
Adult carnivores
Skin with mucus and some with poison glands
Sticky tongue, hinged at the front, attaches to prey
Vomerine teeth- two small nobs help hold in prey
Hind legs adapted for jumping
Frogs are smooth w/ longer legs
Toads are rough w/shorter legs
Most frogs depend on water for life cycle
Females lay eggs in water
Males fertilize them
Larvae are tadpoles
Gills
Feed on algae
Incomplete metamorphosis
Develop into adult frogs
Rate depends on species and food

8. Leopard Frog and Fowler’s Toad

9. Goliath Frog- Conraua goliath
- Largest frog in world
- Found in Cameroon

10. Poison-Dart Frogs- Family Dendrobatidae

12. Frog Characteristics Cloaca- Chamber opening to outside of body
Tympanic membrane- thin membrane that detects vibration (eardrum)
Eustachian tubes- equalize pressure on eardrums
Skin has mucus glands
Mucus is poisonous or foul tasting in most
Nictitating membrane- transparent eyelid
Two teeth in roof of mouth
Swallow food whole
Cloaca- Chamber opening to outside of body
Serves as exit for wastes and gametes
Oviduct- carries eggs to cloaca
Vocal Sacs- Expandable membranes that collect air after passing over vocal cords for louder croaking

13. Amplexus

14. Order Urodela (Caudata- with a tail)
Salamanders
369 species of salamanders, newts, sirens, amphiuma, waterdogs, and mudpuppies
Elongated bodies w/long tails
Smooth, moist skin; Require moisture
External fertilization in water or moist area
Internal fertilization- females insert sperm packet into cloaca
Larvae gilled, carnivorous, smaller version of adult
Some retain gills as adults (neoteny- never lose larval characteristics)

15. Axolotl Salamander that never loses its gills Neoteny
Found in N. america

16. Other Urodela (Caudata)
Newt
Water dog
Amphiuma
Mud puppy

17. Order Caudata- Sirens Aquatic salamanders Have only front extremities
Maintain gills throughout life
Some can vocalize
Most likely external fertilization

18. Order Apoda- Caecilians
Apoda- without legs
Tropical, burrowing amphibians
Small, bony scales embedded in skin
Legless
Carnivorous
Male deposits sperm directly into female
Females may have live young or lay eggs