Biologia

BIOLOGY

AMPHIBIANS

TEACHER

Index

1 What is an amphibian?

2. Why are they called that?

3. Groups of amphibians and how you can identify them?

4. Drawing of an amphibian

5. How do amphibians feed? Description of an amphibians digestive track

6. How do amphibians breathe? Why?

7. Major changes of amphibians during metamorphosis

8. Amphibians circulatory system

9.Nervous system and sense organs

10. Defense mechanisms

11. How do amphibians move

12. Description of an amphibians skeleton

13. Why do frogs inflate their mouth pocket?

14. What is the importance of amphibians

What is an Amphibian?

The word is derived from the Greek "amphibios" which means "double life", referring to the fact that frogs spend half their life near waterbreeding and developing, and the other half away from the water so amphibians are a class of vertebrates ; that do not have amniotic eggs, are ectothermic (term for the animals whose body heat is regulated by the external environment; known as cold-blooded) ;capable of living borh on land and in water.

Almost everyone recognizes a fish, a bird, or a mammal, even a reptile. But what about anamphibian? Most people recognize frogs and toads as amphibians, but these animals are not the only Amphibia, a class of vertebrates (back-boned animals). There are three living groups of amphibians.

Amphibia are a class of vertebrates represented by three orders:

- Anura ( about 4200 species of Frogs and Toads)
- Caudata has about 400 species of salamander and newts.
- Gymnophiona : onehundred and fifty species of wormlike caecilians make up this group.

Most amphibians are characterized by having four legs, moist skin with no scales, gas exchange through skin, lungs, a double-loop circulatory system and aquatic larvae.Frogs, toads and salamanders live in moist areas in a variety of habitats, while newts are aquatic. Caecilians are tropical burrowing animals.

|Frog Parts|
|[pic] |

Amphibians are able to breathe by using lungs or gills or through their skin.
How do amphibians feed?

Most frog larvae are herbivores,whereas salamander larvae are carnivores. However, as adults their diets are similar as both groups become predators and feed on a variety of invertebrates and small vertebrates. Some salamanders and legless amphibians use just their jaws to catch prey. Others, such as frogs and toads, can flick out their long, sticky tongues with great speed and accuracy to catch flying prey.

Describe anamphibians digestive track.

Food moves from the mouth through the esophagus to the stomach, where digestion begins. From the stomach, food moves to the small intestine, which receives enzymes from the pancreas to digest food.
From the intestine, food is absorbed into the bloodstream and delivered to body cells. Food moves from the small intestine into the large intestine before waste material iseliminated. At the end of the intestine is a chamber called the cloaca.
The cloaca is a chamber that receives the digestive wastes, urinary waste, and eggs or sperm before they leave the body.

5 . How do amphibians breathe? Why ?

As larvae, most amphibians exchange gases through their skin and gills. As adults, most breathe through lungs, their thin, moist skin, and the lining of the mouthcavities. Frogs can breathe through their skin either in or out of water. This ability enables them to spend the winter protected from the cold in the mud at the bottom of a pond.

REPRODUCTION AND DEVELOPMENT

Like many amphibians, female frogs lay eggs to be fertilized by males in water. The eggs do not have shells or protective coverings to keep them from drying out.

The eggs are covered...