34 



BREEDING HABITS OF AMPHIBIA 



Breeding normally occurs in April when the temperature is about 52 F. The eggs (about 

 1, 000) are layed singly at night while the pair is floating at the surface of the pond. The 

 male inseminates each egg as it emerges from the cloaca of the female. The eggs are 

 small, about 1. in diameter, and are generally dark in color. Each egg is surrounded 

 by firm jelly. Hatching occurs in 4 to 16 days depending upon the water temperature, and 

 temperature tolerance is from about 42 F. to 83 F. Metamorphosis is reached in 90 to 

 100 days, occurring in July. The eggs are excellent for operative procedures. The tad- 

 poles live on diatoms and algae while the adults feed on insects and spiders. Can be fed 

 Drosophila in the laboratory (preferably the vestigial mutant). 



HYLA VERSICOLOR, the tree frog. This small (2 to 2^ inches) arboreal species is 

 partial to woodlands and bushy areas but may be found far removed from moist areas, 

 around buildings, walls, fences. It is found in eastern United States and Canada. The 

 skin is moist and slightly rough; the toes are webbed and their tips expanded into disks 

 for adhering to tree bark; the back may be uniformly colored or blotched, but is never 

 stripped. There is a white spot under the eye and yellow and brown markings on the groin. 

 These frogs can change their body color considerably. The male has the usual thumb pad 

 and throat characteristics. 



Breeding occurs in quiet ponds surrounded by high vegetation between the middle of May 

 and the middle of June when the air temperature is at least 72 F. Egg-laying takes about 

 an hour, the paired animals depositing about 50 eggs at a time until one or two thousand 

 are layed. The jelly, which holds the entire egg mass together, is of loose consistency. 

 The eggs are brown at the animal pole and yellow or cream at the vegetal pole. The eggs 

 hatch in 4 to 5 days into larvae ^ inch in length. The tadpole reaches a length of 2 inches 

 and metamorphoses in 45 to 60 days, never measuring more 

 than 1 inch. The newly metamorphosed frogs are green and 

 without characteristic markings. The length of life is prob- 

 ably about 9 years. 



These forms are herbivorous, living on minute algae and 

 diatoms in early life and later living on non-aquatic insects. 



PSEUDACRIS NIGRITA , the swamp tree frog. This frog is 

 found widely distributed over the United States (except in 

 New England) and the males rarely exceed 1^ inches and the 

 females 1^ inches in length. It has three broad, dark 

 stripes that extend down the back, and the tips of the toes 

 bear small disks. The skin of the chin and the throat of the 

 male is loose and dark. 



Breeding is in any small body of water, permanent or tem- 

 porary, from the middle of March to the middle of April. 

 About 500 to 1, 500 eggs are layed in clusters. Hatching 

 occurs in about 2 weeks, and larval life lasts from 40 to 90 

 days while the tadpole attains a length of 1^ inches. 



Pseudacris nigrita, 

 the swamp tree frog. 



(Courtesy C. H. Pope 

 1944: Chicago Mus. 

 Nat. Hist.) 



RANA CATESBIANA . the bullfrog. This large frog is found East of the Rockies from 

 Mexico to Canada, and is known to have a life span of 15 years. Its typical haunts are 

 small lakes and permanent ponds with much vegetation, generally shadowed by willows 

 and other low trees. 



The species can be recognized by the fully webbed hind feet, pointed toes, uniformly dull 

 green back (no warts or plicae) and the size of adults ranges from 4 to 8 inches, from 

 snout to anus. The males have a slightly larger tympanic membrane than do the females, 

 a pigmented thumb pad, and yellow throat. 



