1. Amphibians

2. Introduction
Amphibians are a group of vertebrate animals that are well adapted to live in both water & land.

3. Amphibians

4. Living in both water & land is a challenge
Living in both water & land is a challenge. Amphibians need to support their body on land (where they are heavier)…

5. At the same time, they need organs that will allow them to see, hear and breathe in both environments.

6. So… how do they do it?

7. 1. Eyes
Amphibians have a NICTITATING MEMBRANE. It’s completely transparent.
It keeps the eyes moist on land and protected in the water.

8. 2. Hearing Sound waves travel differently in water & air.
They have 2 circular tympanic membranes which work really well at detecting sound waves in air & water.

9. 3. Circulatory System The heart is divided into 3 chambers.
This does a better job at separating O2 rich and O2 poor blood, which makes the system more efficient.

10. 4. Digestive System
Consists of a mouth, esophagus, stomach, small intestine & large intestine.

11. 5. Cloaca
Empties the products of the digestive, excretory and reproductive systems.

12. 6. Lungs
Amphibians are equipped with lungs that take in air and absorb O2 from it.

13. 6. Lungs
Compared to other vertebrates, amphibians’ lungs are very small.

14. So… how do frogs obtain all the oxygen they need?

15. They absorb it through their skin.

16. 7. Skin
Amphibian skin can absorb O2 and exchange it with CO2.

17. 7. Skin
There is one catch, though…

18. 7. Skin
Air molecules are too big to pass through the pores of the skin. They have to be dissolved in water before they can be absorbed. Amphibians have to keep their skin moist all the time.

19. 8. Life Cycle
Amphibians are the only vertebrates that undergo metamorphosis.

20. 8.1 Mating
The male frog clasps the female from her back. The female lays the eggs and at the same time, the male releases the sperm into the water to fertilize the eggs.

21. 8.2 Egg phase
Frogs begin their lives as eggs. They are very soft and must be in a moist place.
They can lay as many as 20,000 eggs!

22. 8.2 Egg phase

23. 8.3 Young Tadpole
Newly hatched amphibians feed from the clear substance that surrounds the egg. After that, they start to feed on algae.

24. 8.4 Developing Tadpole
As they mature, gills and tail disappear while lungs and legs are formed.

25. 8.5 Adult Frog
When they reach this phase, they are capable of feeding on land.

26. A quick word before we’re done…
Although amphibians can live on land, they still highly depend on water:

27. 1. They need it to stay moist, so they can breathe through their skin

28. 2. They need it to mate & fertilize their eggs.

29. 3. They need it to keep their eggs safe & hydrated.

30. 4. They need it to breathe while being tadpoles.

31. 4. They need it to breathe while being tadpoles.

32. Now tell me, what did you learn?