1. Amphibians
Chapter 40

2. Origins & Evolution of Amphibians
Section 40.1
Food!

3. Adaptation to land Amphibian means “double life”
Came out of the water to escape predation & competition for food
Need a strong bony endoskeleton to deal with force of gravity

4. Characteristics of early amphibians
Oldest amphibian fossil is 370 myo
Evolved from lobe-finned fish
Four limbs homologous to pectoral & pelvic fins of fish
Similar skull & vertebrae
some had gills and lungs
More toes than modern
amphibians

5. Diversification of amphibians
Two main evolutionary lines
Modern amphibians
Ancestor of reptiles
4,500 species in 3 orders
Order Anura
Order Caudata
Order Gymnophiona

6. Modern amphibians Metamorphosis Moist, thin skin with no scales
Feet lacking claws & often webbed
Use skin, gills, & lungs to breathe
Eggs lack membrane or shells
Eggs laid in water
Fertilization externally

7. Order Anura Video Meaning “tail-less” Examples: frogs & toads
“toad” = rough, bumpy skin
“frog” = smooth, moist skin
Adaptations for jumping
Tadpole: swimming larvae
Carnivores
Video

8. Order Caudata Video Example: salamanders & newts
Elongated bodies with moist skin and long tails
Live in moist places
Carnivores
Video

9. Order Gymnophiona Video Example: caecilian
Legless & resemble small snakes
Very small eyes, often blind
Carnivores
Video

10. 3 Order Note Cards! Front Side = Order name & picture Back Side =
example organisms
Location of animal on Earth
Habitat/environment
Adaptations for life/ key characteristics
Fun fact!
Anura
Caudata
Gymnophiona

11. Characteristics of Amphibians
Section 40.2

12. External covering Skin = respiration & protection
Mucous glands: supply lubricant to keep skin moist & poison for protection
Poison dart frogs

13. Internal anatomy Strong bony skeleton More developed internal anatomy
Needed for life on land (larger animals)
Pectoral & pelvic girdles help support
More developed internal anatomy
Closer to humans!
video

14. Male internal anatomy a. Large intestine. b. Small intestine.
1. Lung lobes.
2. Heart.
3. Liver lobes.
4. Gall bladder.
5. Stomach.
6. Small intestine.
7. Testis.
8. Fat body.
9. Urinary bladder.

15. Female internal anatomy
1. Liver lobes.
2. Heart.
3. Ovary with eggs.
4. Gall bladder.
5. Small intestine.
6. Stomach.
7. Oviduct.

17. Heart & circulatory system
Two separate loops
Pulmonary circulation: blood from heart to lungs & back to heart
Systemic circulation: blood from heart to muscles & organs then back to the heart

18. Three chambered heart
Right atrium: where (deoxygenated) blood enters the heart from the body
2. Left atrium: where oxygenated blood enters from the lungs
3. Ventricle: main pumping chamber 2. 1. 3.

19. Respiration Larvae respire via gills and skin
Adults respire via lungs and skin
Pulmonary respiration: through lungs
Cutaneous respiration: through skin

20. Digestive system All adults are carnivores New terms:
Pyloric sphincter:
Duodenum:
Ileum:
Mesentery:
Cloaca:
Vent:

21. Excretory system
Two kidneys that filter nitrogenous wastes from the blood
Urine flow:
Kidneys  urinary ducts  urinary bladder  cloaca

22. Nervous system Brain: Nerves Video Olfactory lobes Cerebrum
Optic lobes
Cerebellum
Medulla oblongada
Nerves
10 pair cranial nerves
Spinal cord
Spinal nerves
Video

23. Sense organs
Sight: light travels through nictitating membrane (transparent movable membrane covering the eyes)  eye
Sound: travels through tympanic membrane (eardrum)  columella (small bone) inner ear (embedded in skull)

24. Reproduction of Amphibians
Section 40.3

25. Life cycle

26. Courtship & fertilization
Video
Courtship & fertilization
Males croak to females in spring
Amplexus: male embrace of female during mating
May last for days!
Once female releases eggs, male releases sperm  external fertilization

27. Metamorphosis
Tadpole  frog
Video
The real one

28. Parental care Males often remain with eggs for protection
Example: Darwin’s frog puts eggs in his vocal sac where they hatch, go through metamorphosis, and emerge in the adults form