1. Amphibians
Chapter 40
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Chapter 40 Amphibians

2. Objective 40.1
Describe three preadaptations involved in the transition from aquatic to terrestrial life
Describe two similarities between amphibians and lobe-finned fishes
List five characteristics of living amphibians
Name the three orders of living amphibians and give an example of each
Chapter 40 Amphibians

3. Origin and evolution of amphibians
About 360 million years ago, amphibians became the first vertebrates to live on land. The name amphibian comes from the Greek word meaning “double” and “life” and reflects the fact that many amphibians spend part of their life on land and part in water.
Chapter 40 Amphibians

4. Adaptation to land Most likely evolved from lobe-finned fishes
Preadaptatins are adaptations in an ancestral group that allow a shift to new functions which are later favored by natural selection
Fins had bone structure to walk as legs
Modified pouches in digestive track  lungs
Chapter 40 Amphibians

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6. Characteristics of early amphibians
Skull and vertebra column, bones in fin and (similar)
Scarcopterygian- extinct lobe-finned fish
360million years fossil record
Had 4 strong limbs
Gills, teeth, lateral lines
Most likely spent most time in water
Chapter 40 Amphibians

7. Diversification of amphibians
Devonian period and carboniferous period amphibians split into 2 main evolutionary lines
One modern amphibians
Ancestors of reptiles
4500 species of amphibians
3 orders of amphibians
O. Anura – frogs and toads (3900 species)
O. Caudata- salamanders (400 species)
O. Gymnophiona – caecilians (legless tropical)
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9. Modern Amphibians Aquatic larval to terrestrial adult (metamorphosis)
Moist thick skin with no scales
Feet- lack claws, webbed
Gills, lungs, skin in respiration
Eggs lack muticellular membranes or shells
Eggs laid in water- external fertilization
Chapter 40 Amphibians

10. Objective 40.2
Relate the structure of amphibians skin to the types of habitats in which amphibians can survive
Identify three adaptations for the life on land shown by the skeleton of a frog
Sequence the flow of blood through an amphibian’s heart
Describe the digestive/ excretory systems
Discuss the nervous system
Chapter 40 Amphibians

11. Characteristics of amphibians
As you have already seen, terrestrial vertebrates face challenges that are far different from those faced by aquatic vertebrates. In this section you will learn about some of the ways amphibians meet the challenges of living on land.
Chapter 40 Amphibians

12. skin Two important functions Respiration Protection
Moist, permeable to gases and water
Numerous mucous glands keeps skin moist
Can also secrete- foul taste/ poison
Live in moist areas
Tend to be active at night
Can be affected by environment (indicators)
Chapter 40 Amphibians

13. skeleton Strong internal skeleton Bear weight of body
Strong limbs to support body
Ability to jump and land
Chapter 40 Amphibians

14. Circulatory system 2 separate loops
Pulmonary circulation- carries deoxygenated blood from heart to lungs and back to heart
Systemic circulation- carries oxygenated blood from the heart to the body and back to the heart
3 chambered heart
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16. Respiration Larval by gills and skin
Adult – lungs (pulmonary respiration) and skin (cutaneous respiration)
Positive pressure breathing- pumps air into the lungs
Chapter 40 Amphibians

17. Digestive system Carnivorous
Small insects, arthropods, mice, snakes, fish, amphibians, birds
Larva- herbivores (algae, bacteria, plants)
Pharynx  esophagous  stomach  liver  gallbladder  small intestine  large  cloaca
Chapter 40 Amphibians

18. Excretory system Kidney (primary) filter nitrogen and waste
Flushed out as urine
Kidney  urinary ducts  cloaca  urinary bladder (water storage) can be reabsorbed during dry times
Transform ammonia into urea
Chapter 40 Amphibians

19. Nervous system Brain (same size as fish)
Olfactory lobes (sense of smell)
Long lobes of cerebrum (behavior learning)
Optic lobes – process info from eyes
Cerebellum- muscular coordination
Medulla oblongata- organ functions, heart
10 pairs of cranial nerves
Chapter 40 Amphibians

20. Sense organs Lateral lines (only in water)
Nicitating membrane- covering of eyes
Tympanic membrane- eardrum
Columella- small bone that extends between the tympanic membrane and the inner ear
Chapter 40 Amphibians

21. Objective 40.3
Explain how a male frog attracts a female of the same species
Discuss the reproductive system in frogs
Describe the changes that occur during metamorphosis in frogs
Identify two examples of parental care in amphibians
Chapter 40 Amphibians

22. Reproduction in amphibians
One of the biggest differences between aquatic and terrestrial life-forms is their method of reproduction. Most amphibians depend on water for reproduction. They lay their eggs in water and spend the early part of their lives as aquatic larvae.
Chapter 40 Amphibians

23. Courtship and fertilization
Mating call- frogs croak
Males have vocal sacs
Female responds to same species
External fertilization
Eggs  tadpoles  hind legs appear  frog legs appear  young frog  adult
Thyroxine – produced by thyroid gland to stimulate metamorphosis
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25. Parental care Parent care can increase chances of survival
Male remain with eggs
Rhinoderma darwinni- takes them in vocal sacs till hatch
Gastric –brooding frogs in Australia- swallow eggs
Eleutherodactylus- sit on eggs
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28. Virtual Dissections
Chapter 40 Amphibians