CHAPTER V 



THE BULLFROG AS A TYPICAL VERTEBRATE 



ANIMAL 



(CLASS AMPHIBIA) 



(By Ottys Sanders, Southwestern Biological Supply Company) 



As there are many vertebrate animals which lead an amphibious 

 life, it was natural for Linnaeus to group these together under the 

 class Amphibia. This, of course, was classification based on habits 

 rather than on structure, and as soon as such animals as the seal 

 and crocodile were studied structurally they were removed from 

 the class. Today the name is restricted to a group of vertebrates 

 which we know as frogs, toads, salamanders, and caecilians. They 

 are intermediate between fishes and reptiles. They have paired 

 limbs, usually with fingers and toes, and never have paired fins like 

 fishes. They have a moist, naked skin lacking the protective hair 

 of mammals or the feathers of birds. With the exception of 

 caecilians, they do not have scales as do the reptiles. The caecilians, 

 none of which has been reported from the United States, are worm- 

 like burrowing creatures of the tropics. They have small scales 

 between their transverse body rings, although these are not usually 

 seen unless a dissection is made. The amphibians are cold-blooded 

 vertebrates, in contrast to the warm-blooded mammals and birds. 



The frogs, toads, and salamanders usually lay their eggs in water. 

 These develop into tadpoles or larvae breathing with gills before 

 metamorphosing to become adults which breathe with lungs. A few 

 species of frogs and salamanders lay their eggs on land and pass 

 their entire development in the egg. 



There are other exceptions to the general characteristics of this 

 diverse class. A large group of salamanders, the plethodontids, do 

 not have lungs even as adults, and their respiration takes place 

 through their skin, which is richly supplied with blood vessels. 



Habitat of the Bullfrog 



The bullfrog is a solitary animal except during the breeding season. 

 It is strictly aquatic and does not leave the pools as does the leopard 



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