BREEDING HABITS OF AMPHIBIA 



35 



Its natural food in the larval stage is diatoms and algae; as young frogs it is insects and 

 other small invertebrates; and as adults, any moving object, invertebrate or vertebrate, 

 that can be ingested. This includes fish, frogs, salamanders, young turtles, moles, 

 mice, and even birds. In the laboratory the bullfrog may be fed smaller frogs. 



Oviposition of Rono cates- 

 beiana; lateral view. 



(From Aronson 1943: Am. Mus. Nov. #1224) 

 The male bullfrog, (Artist Mr. Richmond E. Lawler) 



Rana catesbiana. 



{Courtesy C. H. Pope 1944: 

 Chicago Mus. Nat. Hist. ) 



The breeding season depends upon the latitude, but ranges from June to August. The air 

 temperature must be at least 72°F. and the bottom water temperature at least 66 C. be- 

 fore the eggs are layed. The eggs are small, but as many as 20, 000 may be layed by a 

 single female, and the egg jelly is loosely applied. The eggs will develop between 59°F. 

 and 90°F. , and the hatching span at 68°F. is about 134 hours. There is a long larval 

 (tadpole) life, the mature tadpole of 4 to 6 inches total length being ready to metamor- 

 phose 2 or 3 years after the egg is layed. Metamorphosis generally occurs in late July 

 and in August. 



RANA CLAMITANS , the green frog is found where 

 bullfrogs are found but they prefer permanent, 

 plant-grown aquatic ponds, swamps, meadows, and 

 slow streams. It is a common form in Eastern 

 North Annerica, even at considerable altitudes. 



The green frog can be recognized by its predomi- 

 nantly green back, with small and widely separated 

 spots, paired ridges of skin from the eyes backward 

 along the back, and webbed and pointed toes as in 

 the bullfrog. It is rarely more than 4 inches in body 

 length. The tympanum is usually very large, and 

 this is the most readily determined difference be- 

 tween the green frog and immature bullfrogs. 



The tadpoles, which grow slowly, feed on diatoms, 

 and algae; the young frogs and adults eat insects, 

 Crustacea, spiders, snails, earthworms. The food 

 consists largely of non-aquatic forms. 



The male Rana clamitans, the 

 green frog, with inflated vocal 

 sacs as seen from above. 



(Courtesy C. H. Pope 1944: 

 Chicago Mus. Nat. Hist.) 



