396 



METAZOAN PHYLA 



Snakes are more abundant in the tropics than elsewhere and are 

 frequently absent from islands, though found on the adjacent continents. 

 Some snakes Hve mostly in and about fresh water; some live in salt 

 water; others are subterranean, burrowing in the ground; while still others 

 are expert tree climbers. The largest of snakes are a python found in 

 Burma, which reaches a length of over 30 feet, and an anaconda of the 

 region of the Amazon in South America, which may approach 40 feet 



in length. 



419. Venomous Snakes. — The sea snakes are very poisonous. They 

 are tropical forms found in the Indian Ocean, the adjacent parts of the 

 Pacific, and along the western coast of South America. They belong 



Fig. 285. — A water moccasin or cottonmouth, Agkistrodon piscivorus, living in the 

 lagoons and sluggish streams of the southeast U. S. A very poisonous snake. {From 

 Ditmars, "Snakes of the World," by courtesy of The Macmillan Company.) 



to the same general group as the coral snakes and the cobras, all having 

 tubular fangs in the anterior part of the upper jaw, in connection with 

 which are poison glands which secrete a very effective venom. The 

 cobras are found in India, China, the Malay Archipelago, and Africa. 

 These snakes are capable of expanding the anterior part of the body 

 and of raising the head and that part of the body well off the ground. 

 In this attitude they strike. India is outstanding for the number of 

 species of venomous snake living in its area and many people die there 

 from snake bites each year. 



Among the snakes called vipers are the pit vipers, represented in 

 the New World by the many species of rattlesnakes (Fig. 284), the water 

 moccasin (Fig. 285), and the copperhead. In all of these the young are 

 brought forth alive. The water moccasin, found in southern United 

 States, is one of the most poisonous of all snakes. The copperhead 

 (Fig. 286), found farther north, is also very venomous. Rattlesnakes 



