2. Amphibians I. Characteristics of Amphibians

3. Introduction Why would water creatures (fish) want to move on land? Why would this be advantageous?

4. A. Belong to the class Amphibia (means double life)

5. Amphibia – “double life” 1. Rely on water for reproduction. 2. Rely on land for life.

6. B. Are cold blooded (ectotherms)

7. 1. They cannot control their body temperature. 2. Their body temperature is close to the temperature of their surroundings.

8. C. Adaptations for land and water life:

9. 1. When conditions get bad, they enter a state of dormancy.

10. a. Another name for dormancy is torpor.

11. b. Torpor in the winter is called hibernation.

12. c. Torpor in the summer is called estivation.

13. 2. Change from the aquatic larva stage to the terrestrial adult form is called metamorphosis.

14. Stages of metamorphosis 1. Fertilized egg 2. Legless tadpoles (aquatic organisms) 3. Tadpoles with legs 4. Immature frog ready for land 5. Adult frog (terrestrial organism)

15. 3. Have thin, smooth, moist skin with no scales.

16. 4. If feet are present, they are webbed with no claws.

17. 5. Use gills, lungs, skin, and mouth cavity for breathing.

18. 6. Larva have a 2 chambered heart & adults have a 3 chambered heart.

19. 7. Eggs do not have a shell and must be laid in water or a moist environment.

20. II. Classification A. Four orders of amphibians.

21. Four Orders of Amphibians 1. Order Anura 2. Order Urodela 3. Order Apoda 4. Order Trachystoma

22. 1. Order Anura (without a tail) Frogs & toads

23. a. Frogs 1. Smooth, moist skin with short, broad bodies.

24. 2. Powerful hind legs. 3. Most live in or near water, some species live in trees.

25. Frog

26. www.leopardfrog.com

27. Horned Frog

28. Red eyed Tree Frog

29. b. Toads 1. Dry, bumpy skin with stocky bodies.

30. 2. Toad is a term used to describe members adapted to dry environments.

31. Fire bellied toad

32. c. Order Anura – Larval Forms Larval forms are called tadpoles. (This applies to both frogs & toads)

33. Tadpoles

34. 2. Order Urodela (visible tail) a. Salamanders

35. 1. Elongated body with long tail. 2. Smooth, moist skin.

36. 3. Live in water or under logs and stones.

37. Fire Salamader

38. b. Newts Aquatic species of the Order Urodela are called newts.

39. Newt

40. III. External Anatomy A. Legs 1. Muscular hind legs for jumping 2. Front legs for support

41. B. Eyes 1. Protrude from the head to see above the water. 2. Have a 3 rd eyelid to keep eye moist (nictitating membrane)

42. C. Nares (nostrils) D. Tympanic Membrane -picks up vibrations in the air or water for hearing

43. IV. Internal Anatomy A. Mouth Cavity 1.Large size for catching insects

44. 2. Tongue is attached to the front floor of the mouth. It’s very sticky and has projections at the free end.

45. 3. Eyes can be pulled into mouth to help push food down the throat.

46. 4. Two types of teeth A. Vomerine teeth – two teeth that project from the roof of the mouth; used to hold insects.

47. B. Maxillary teeth – found only in the upper jaw; used to hold insects. (These teeth can be felt)

48. 5. Internal nostrils – take in air.

49. 6. Eustachian tubes – leads to middle ear

50. 7. Vocal Sacs – ONLY in male frog to amplify voice.

51. 8. Esophagus – leads to stomach. 9. Glottis – passage between the throat and lungs.

52. B. Skeletal System 1. It’s designed to allow neck movement. 2. Spine is made up of 9 vertebrae. 3. No ribs are present.

53. C. Digestive System 1. Alimentary Canal – the front tube from beginning to end; it includes ALL organs.

54. 2. Food passes down the short esophagus into stomach. The stomach is “J” shaped.

55. 3. Small intestines Looped many times to absorb digested food; there are 3 parts to the small intestines.

56. 1. Duodenum – the upper part 2. Jejunum – the middle part 3. Ileum – the lower part.

57. 4. Large Intestines Undigested wastes are collected here and passed into a cavity called the cloaca. (ALL urine, solid waste, and sex cells must pass through the cloaca before exiting the body.)

58. 5. Substances then pass to the outside through the cloacal opening or anus.

59. 6. Other Digestive Organs a. Liver – produces bile b. Gall bladder – stores bile c. Pancreas – produces insulin d. Fat bodies – around the kidneys to store food for hibernation and estivation.

60. D. Circulatory System 1. Tadpoles have a 2 chambered heart. 2. Frogs have a 3 chambered heart. (2 atrium & 1 ventricle)

61. Three chambered heart a. Left atrium – receives oxygen “rich” blood from the lungs. b. Right atrium – receives oxygen “poor” blood from the body.

62. c. Ventricle – blood from both atria is mixed here. Some is pumped to the lungs, the rest goes to the body.

63. E. Respiratory System 1. Tadpoles breathe through gills 2. Adult frogs breathe 3 ways: 1. Lungs 2. Skin 3. Mouth

64. F. Excretory System 1. Most carbon dioxide is released through the skin. 2. Kidneys filter blood and form urine.

65. G. Nervous System 1. More complex than fish 2. 5 lobes of the brain

66. Lobes of the brain a. Optic –sight & sense organs b. Olfactory – smell c. Cerebrum – instincts d. Cerebellum – muscle activity e. Medulla oblongata – internal organs

67. H. Reproductive System 1. ALL amphibians must reproduce in water or a moist environment. 2. All are dioecious (male & female)

68. 3. Breed once a year in the spring. WHY? 4. Males use vocal sacs to attract females. 5. No external sexual characteristics.

69. 6. Fertilization – “Amplexus Process” 1. Male climbs onto the back of the female and grasps firmly with forelegs and presses down on the females abdomen to help expel the eggs.

70. 2. Direct fertilization – eggs are expelled and the male releases sperm directly on the eggs to fertilize them. (in an aquatic environment)

71. 3. Eggs hatch into tadpoles in about 12 days.

72. The End