1. CHAPTER 11.3
Amphibians

2. POINT > Identify characteristics of amphibians POINT > Describe the life cycle of a frog POINT > Explain how amphibians get O2, circulate blood, get food, and move POINT > Define atrium and ventricle POINT > Explain how amphibians are environmental indicators

3. POINT > Identify characteristics of amphibians
Amphibian means “double life” Amphibians live part of life in the water and part on land Amphibians were the first vertebrates to live on land! Still need water for reproduction First tetrapods! (4 legs)

4. CHECK:
What does “amphibian” mean?
Why are amphibians important in evolution?
What is a tetrapod?

5. POINT > Identify characteristics of amphibians
3 Groups:
1. Frogs and toads
2. Salamanders and
newts
3. Caecilians

6. POINT > Describe the life cycle of a frog
Frogs go through a metamorphosis:
Eggs hatch in water as fish-like
tadpoles, that breath with gills
Tadpoles grow rear and then front legs and transition to land as adults. Adults breath with lungs.

7. POINT > Describe the life cycle of a frog
Newborn salamanders also begin life in water with gills, but look like small adults (not as much metamorphosis)

8. Tadpoles get oxygen with gills and have a 2-chambered heart
POINT > Explain how amphibians get O2, circulate blood, get food, and move
Tadpoles get oxygen with gills and have a chambered heart
Adults amphibians develop lungs and a 3-chambered heart
Many adult amphibians also exchange gases through the skin

9. CHECK:
How do tadpoles get oxygen?
What are two ways adult amphibians get oxygen?

10. POINT > Define atrium and ventricle
The atrium and ventricle are the chambers of the hearts of vertebrates
The ventricle is usually more muscular than the atrium because it pumps blood with more force

11. POINT > Explain how amphibians get O2, circulate blood, get food, and move
Amphibians lay soft, jelly-like eggs. They must be in water or they will dry out!
Frogs/toads fertilize eggs externally
Larva wriggle out after a few days into the water

12. CHECK:
Why do amphibians have to lay their eggs in water?

13. POINT > Explain how amphibians get O2, circulate blood, get food, and move
Tadpoles are usually herbivores Adults amphibians are usually carnivorores

14. POINT > Explain why amphibians are environmental indicators
Amphibian populations have been in steep decline world-wide
Causes include habitat destruction, increased UV radiation, acid rain, and chemical pollution
Amphibians are sensitive to the environment because of their thin and moist skin
This makes amphibians an indicator of environmental deterioration

15. CHECK:
What are three possible reasons for population declines in amphibians?
Why are amphibians especially vulnerable to environmental changes?

16. Amphibian videos http://www.youtube.com/watch?v=KRbVJGMlSZE salamander
amphibians on the edge

17. HOMEWORK Read Chapter 12.3 Complete Study Guide
Complete 12.3 Section Assessment page 386
GRAS Pages