AMPHIBIA 



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adult life they spend most of their time on the trunks of trees. 

 Another common amphibian is the newt, a salamander. This 

 smooth-skinned, four-limbed animal, often incorrectly called a 

 lizard, passes its larval lif e in the water, where it breathes by means 

 of external gills. Later it loses its gills, becomes provided with 

 lungs, and comes out on land, but after two years it goes back to 

 the water again to lay its eggs. 



Some salamanders never have lungs, but breathe through the 

 moist skin. Still other amphibians are the mud puppies, sirens 

 or mud eels, and the axolotl. 



Practical Exercise 15. Name all the amphibians in your locality. Why is 

 the frog an amphibian? What other animals outside the amphibians could 

 you consider as amphibious animals ? 



Practical Exercise 16. Compare the life history of a toad with that of a 

 frog. 



Amphibia. As the name indicates (amphi, both, and bios, life), 

 members of this group live during their life history both in water 

 and on land. In the earlier stages of their development they take 

 oxygen into the blood by means of gills. When adult, however, 

 they breathe by means of lungs. At all times, but especially 

 during the winter, the skin serves as a breathing organ. The skin 

 is soft and unprotected by bony plates or scales. The heart has 

 three chambers : two auricles and one ventricle. Most amphib- 

 ians undergo a metamorphosis, or change of form, the young 

 being unlike the adults. About 1500 species are known. 



AMPHIBIA 



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Order 1. Urode'la. Amphibia having poorly developed appendages. Tail persistent 



through life. Examples : mud puppy, newt, salamander. 

 Order 2. Anu'ra. Tail-less Amphibia, which undergo a marked metamorphosis, breathing by 



gills in larval state, by lungs in adult state. Examples : toad and frog. 



