1. Chapter 19
Amphibians
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2. Amphibians are tetrapods
Amphibians are tetrapods The three thousand modern species are a mere remnant of this once-diverse group. Caudata, the salamanders; Anura, the frogs and toads; and Gymnophiona, the caecilians.

3. Table 19.1

4. Fig. 19.5c

5. Most terrestrial salamanders live in moist forest-floor litter and have aquatic larvae. Salamanders in the family Plethodontidae are the most fully terrestrial salamanders The family Salamandridae are commonly called newts. They spend most of their lives in water and frequently retain caudal fins.
Order Caudata

6. Most salamanders have internal fertilization
Most salamanders have internal fertilization. Males produce a pyramidal, gelatinous spermatophore that is caped with sperm and deposited on the substrate. Females pick up the sperm cap with the cloaca and store the sperm in a special pouch, the spermatheca. Larvae similar to adults; possess external gills, a tail fin, paedomorphic; that is, they become sexually mature while still showing larval characteristics.

7. Fig. 19.5a

8. Fig. 19.5b

9. Order Gymnophiona
Zoologists have described about 160 species confined to tropical regions; Feed on worms and other invertebrates in the soil. A retractile tentacle between their eyes and nostrils may transport chemicals from the environment to olfactory cells in the roof of the mouth. Larval stages are often passed within the oviducts, scrape the inner lining of the oviducts Other caecilians lay eggs

10. The order Anura includes about 3,500 species of frogs and toads
The order Anura includes about 3,500 species of frogs and toads. Anurans live in most moist environments, larval stages, called tadpoles, Anuran larvae undergo a drastic and rapid metamorphosis from the larval to the adult body form.

11. The distinction between “frog” and “toad” is more vernacular than scientific. “Toad” usually refers to anurans with relatively dry and warty skin A number of distantly related taxa have these characteristics. True toads belong to the family Bufonidae.

12. External Structure
The skin of amphibians also functions in gas exchange, temperature regulation, and absorption and storage of water. Highly glandular; keep the skin moist to prevent drying sticky secretions; toxic chemicals Chromatophores are specialized cells for skin color and color changes.

13. Support and Movement
The amphibian skull is flattened, is relatively smaller, and has fewer bony elements than fish’s Supportive processes called zygapophyses on each vertebra prevent twisting. The first vertebra is a cervical vertebra, The last trunk vertebra is a sacral vertebra. A ventral plate of bone, called the sternum, is present in the anterior ventral trunk

14. Fig. 19.8a

15. Fig. 19.8b

16. Fig. 19.9 腓骨

17. The pelvic girdle of amphibians consists of three bones (the ilium, ischium, and pubis) these bones, which are present in all tetrapods, but not fishes, are important for support on land. Terrestrial salamanders also move ; that throw the body into a curve to advance the stride of a limb. The long hindlimbs and the pelvic girdle of anurans are modified for jumping.

18. Nutrition and the digestive system
Most adult amphibians are carnivores that feed on a wide variety of invertebrates. Most larvae are herbivorous and feed on algae and other plant matter. Most amphibians locate their prey by sight and simply wait for prey to pass by. Salamanders, using only their jaws to capture prey.

19. Nutrition and the digestive system
Anurans, use their tongue and jaws in a flip- and-grab feeding mechanism; Mucous and buccal glands on the tip of the tongue exude sticky secretions; Lunges forward and flicks out its tongue; Lower jaw is depressed. The head tilts on its single cervical vertebra; in 0.05 to 0.15 second
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21. Circulation, gas exchange ….
Gas exchange occurs across the skin of amphibians Therefore, blood entering the right side of the heart is nearly as well oxygenated as blood entering the heart from the lungs. Submerged; Blood coming into the right atrium has a higher oxygen concentration than blood returning to the left atrium from the lungs.
Circulation, gas exchange ….

22. Fig
頸動脈
肺動脈
肺血管
右心房
動脈錐 分格 心室

23. Fig

24. This adaptation is especially valuable for those frogs and salamanders that overwinter in the mud at the bottom of a pond. Carotid artery (aortic arch III), takes blood to the head; systemic artery (aortic arch IV), which takes blood to the body; or the pulmonary artery (aortic VI). Lymphatic system that returns fluids, proteins, and ions filtered from capillary beds in tissue spaces to the circulatory system. Contractile vessels, lymphatic hearts, that pump fluid through the lymphatic system.

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26. Skin of amphibians is moist; also richly supplied with capillary beds
Skin of amphibians is moist; also richly supplied with capillary beds. Gas exchange across the skin is called cutaneous respiration; 30 to 90% Across the surfaces of the mouth and pharynx. This buccopharyngeal respiration; 1 to 7% Pulmonary (lung) ventilation occurs by a buccal pump mechanism. At 5℃ 70% across the skin and mouth; at 25℃ 30%

27. Fig

28. Temperature regulation
Amphibians are ectothermic; heat-absorbing properties of the water. Temperature regulation is mainly behavioral. Basking after a meal is common because increased body temperature increases the rate of all metabolic reactions Critical temperature extremes for some salamanders lie between -2 and 27 ℃, and for some anurans between 3 and 41 ℃

29. Nervous and sensory
The forebrain contains olfactory centers and regions that regulate color change The midbrain contains a region called the optic tectum that assimilates sensory information and initiates motor responses. The hindbrain functions in motor coordination and in regulating heart rate and the mechanics of respiration. The lateral-line system is similar in structure respond to low-frequency vibrations in the water

30. 虹彩 角膜 鞏膜
水晶體
脉絡膜 網膜 瞬膜
下眼皮

31. The lower eyelid is movable, and it cleans and protects the eye; nictitating membrane; Orbital glands The iris can dilate or constrict to control the size of the pupil. Light rays to a focal point on the retina. Focuses on distant objects when the eye is at rest. To focus on near objects, the protractor lentis muscle must move the lens forward. Receptors called rods and cones are in the retina. Because cones are associated with color vision in some other vertebrates

33. The auditory system; Both substrate-borne and airborne vibrations; The ears of anurans consist of a tympanic membrane, a middle ear, and an inner ear. Abutting the tympanic membrane is a middle-ear ossicle called the stapes (columella), which transmits vibrations of the tympanic membrane into the inner ear.

34. Low-frequency (100 to 1,000 Hz); front appendages and the pectoral girdle through operculum
High-frequency (1,000 to 5,000 Hz) through tympanic membrane 鐙骨
鰓蓋骨

35. Mating calls are high-frequency sounds that are of primary importance for only a part of the year. At other times, low-frequency sounds may warn of approaching predators.

36. Excretion and osmoregulation
The kidneys lie on either side of the dorsal aorta on the dorsal wall. Amphibians that live in freshwater excrete ammonia. Amphibians that spend more time on land excrete urea that is produced from ammonia in the liver. Amphibians must conserve water; Amphibians limit water loss by behavior that reduces exposure to desiccating conditions.

37. Many amphibians reduce evaporative water loss by reducing the amount of body surface exposed to air; Curl their bodies and tails; Closely packed aggregations Forming cocoons that encase the body during long periods of dormancy. Flattens its body on moist surfaces; the ventral pelvic region, absorbs water.

38. Reproduction, development,….
A few anurans have terrestrial nests, In a few species, larval stages are passed in the egg membranes Only about 10% of all salamanders have external fertilization. All others produce spermatophores, and fertilization is internal. All caecilians have internal fertilization, and 75% have internal development.

39. In temperate regions, temperature seems to be the most important environmental factor in mate In tropical regions, amphibian breeding correlates with rainy seasons. Salamanders rely primarily on olfactory and visual cues whereas male vocalizations and tactile cues are important for anurans.

40. The male grasps the female –his forelimbs around her waist Amplexus and may last from 1 to 24 hours. During amplexus, the male releases sperm as the female releases eggs.

41. Vocalization
Advertisement calls attract females to breeding areas and announce to other males that a given territory is occupied. Reciprocation calls to indicate receptiveness. Release calls; Distress calls; in response to pain or being seized by a predator. The calls may be loud enough to cause a predator to release the frog.

42. The sound-production apparatus of frogs consists of the larynx and its vocal cords. Also possess a vocal sac. Air from the lungs is forced over the vocal cords 聲帶

43. Fig a 喉

44. Fig b

45. Parental Care
The most common form of parental care in amphibians is attendance of the egg clutch by either parent. Maternal care occurs in species with internal fertilization (predominantly salamanders and caecilians) Pipa carry eggs on their backs Rheobatrachus females brooded tadpoles in their stomachs, During brooding, the female’s stomach expanded to fill most of her body cavity,

46. Metamorphosis is under the control of neurosecretions of the hypothalamus (丘腦下部), hormones of the anterior lobe of the pituitary gland (垂腺), and the thyroid gland (甲狀腺). Some salamanders are paedomorphic because cells fail to respond to thyroid hormones, whereas others are paedomorphic because they fail to produce the hormones associated with metamorphosis.

47. Fig a

48. Fig b

49. Fig c

50. Fig d

51. Acid deposition and ultraviolet radiation
Acid deposition and ultraviolet radiation. A pH of 5 or less will kill most embryos times more acidic to 320 nm range deplete the ozone shield of the earth