FIELD BOOK OF PONDS AND STREAMS 



Amphibians are timid animals and their chief defense is in 

 flight or concealment. They do net bite and they neither 

 scratch nor sting. None of our native species is poisonous 

 or harmful. It is true that the skin of a maltreated toad gives 

 off a milky fluid which is peppery and irritating; any dog 

 which picks up a toad usually drops it quickly, but is rarely 

 badly poisoned by it. 



Habitat. — Frogs and toads live in ver}^ difl'erent places 

 during different seasons and stages of their lives. So long as 

 they are tadpoles or lar\^ae they all live in the water, but the 

 air-breathing adults take to the land, the frogs generally 

 keeping to marshes and meadows and damp woods, and the 

 toads going to shaded spots in gardens and roadsides. They 

 vary in their choice of winter hibernation places; some hide 

 beneath stones, others dig into the bottoms of streams and 

 ponds. But in spring, they are sooner or later to be found in 

 the water; there they lay their eggs, and there the fishlike 

 tadpoles hatch and grow to adult form. American sala- 

 manders are more apt to spend their lives either entirely in the 

 water or entirely upon land, but some of them, like the spotted 

 salamander, Amhy stoma maculatum, live in the water until 

 they become adults, then clamber out and live on land 

 hidden beneath stones and logs, but return to the water to 

 lay their eggs. 



Food. — Frog and toad tadpoles are mainly vegetable 

 feeders, preferring filamentous algae like Spirogyra or desmids 

 and diatoms. After transforming they become carnivorous, 

 eating insects, snails, worms, and the like. In their new form 

 even the shape of the food canal is changed, from the long 

 intestine coiled like a watch-spring such as can be seen through 

 the body wall of a big bullfrog tadpole to the short one charac- 

 teristic of carnivorous animals (Fig. 284). Salamanders are 

 carnivorous in both larval and adult stages, thriving upon 

 worms and water insects, mollusks, and small tadpoles of their 

 own species. 



348 



