100 MARY HONORA SAYLE 



DISCUSSION 



Let us try to picture Necturus in its daily life on the bottom 

 of a lake or slow flowing stream. It frequents quiet waters 

 from four to eight feet deep where a clean, sandy bottom is 

 fairly well covered by vegetation. During the day it rests 

 quietly beneath boards, logs or stones. One is rarely fortunate 

 enough to get a glimpse of it; it is extremely shy and disappears 

 at the slightest disturbance of the water, such as that caused 

 by the approach of a boat. In walking, the diagonally opposite 

 legs move in unison. When disturbed it swims swiftly, with a 

 vigorous lateral motion of the broad and powerful tail, the feet 

 being held closely against the body. Necturus never swims 

 long distances, at most a few yards, then seeks concealment 

 either in the mud or beneath some object. If it is undisturbed 

 it usually rests with its head protruding from beneath a rock. 

 The animal thus presents a curious appearance with its ruby 

 gills moving gracefully to and fro. When one is disturbed the 

 gills change from bright red to a dusky color and are at once 

 drawn down tightly against the neck. 



During the night Necturus moves from place to place. If it 

 wanders into a warm area it becomes restless and walks away 

 quickly into cooler water. It may approach dead vegetation 

 that is giving off acids and alcohol. Such an environment 

 drives Necturus away immediately. If it swims into an area 

 containing an excess of salts or alkalies it quickly withdraws. 

 Thus Necturus moves about, being directed hither or thither 

 by the various changes in the chemical constitution or temper- 

 ature of the water, till it comes into cool, pure water. Here 

 it seeks crustaceans, insect larvae, small fish and earthworms, 

 which constitute its food. 



From the consideration of the facts of behavior one is natur- 

 ally led to ask what the artificial conditions are which best 

 suit the needs and instincts of Necturus. In aquaria it avoids 

 the sunlight, and always seeks concealment. A tank well sup- 

 plied with dark sheltered nooks is therefore best. Necturus can 

 not live in warm water, and hence an aquarium should be sup- 

 plied with running water and kept cool. Everything should be 

 kept free from fungus, for a Necturus infected with Sapro- 

 legnia will not live long. 



When Necturi are kept in aquaria they are frequently ob- 



