90 



SEA SNAKES 



under them and haul them up on board. Most are caught in this way 

 at night with the aid of a hght. In the daytime most sea snakes are 

 presumably submerged, hunting their prey on the bottom and probably 

 catching it visually, though this cannot be known for certain. From time 

 to time they must come up to breathe, for, of course, like other snakes 

 they breathe by means of lungs. How long they can remain submerged is 

 uncertain, but by calculation based on the capacity of their lungs, meta- 

 bolism, and other factors I have previously deduced that it is probably a 

 matter of hours. After my departure some "drowning" tests were made on 

 sea snakes. Although in these experiments the snakes at first writhed 

 vigorously in their attempts to get out of the closed container, and so 

 consum.ed far more oxygen than normally, they remained alive for over 

 two hours, which agrees very well with the result I had arrived at by in- 

 direct means. 



On the bottom the snakes doubtless lie quietly in wait for their prey, 

 which they then catch by a rapid attack exactly like their terrestrial rela- 

 tives. In their stomachs we found only bottom-dwelling fish, and eels 

 of various species seem to be a special favourite. For the rest, there is 

 undoubtedly a difference in the choice of prey and method of catching 

 it as between different species of sea snake; the great variations in the 

 shape of the head and the forepart of the body certainly suggest this. 

 There is one genus, Microcephalophis, in which the head is no bigger 

 than a fingernail and the forepart of the body no thicker than a little 

 finger, while the hindpart is as thick as an arm. One is tempted to sup- 

 pose that this snake crawls about coral reefs exploring narrow fissures 



The physiognomy of sea snakes shows great variations. The four species illustrated reveal clear 

 differences in shape of head, size of mouth, siting of eyes, coloration, and other features. 



