SEA SNAKES 

 By H. VoLS0E 



When introduced, during my stay on the Galathea, as a speciaHst in sea 

 snakes, I invariably got a look of polite interest mingled with a good pro- 

 portion of scepticism. Clearly, most people doubted the existence of such 

 things and thought I was joking. It was necessary to put on a serious 

 scientific face in order to convince them that there really are such crea- 

 tures and that they probably have nothing at all to do with the Great 

 Sea Serpent which obviously underlay their scepticism. 



There are some fifty species of sea snakes. They form a well-defined 

 group whose nearest relatives are the cobras, with which they are classed 

 as Proteroglypha, a group characterized by a well-developed, rigidly at- 

 tached fang at the front end of the upper jaw. The highly virulent venom 

 flows through a canal in the fang into the wound inflicted by the snake's 

 bite. 



My interest in the subject springs from the fact that a number of years 

 ago I worked on some sea snakes brought home by Danish fishery expe- 

 ditions from the Persian Gulf. With the exception of one, which for a 

 short time was kept alive in a jam-jar, the material consisted of preserved 

 specimens. My study of these snakes and the literature about them con- 

 vinced me that the biology of sea snakes presents many absorbing prob- 

 lems which we can only hope to solve by observing them in their natural 

 environment and possibly making experiments on live animals. As the 

 Galathea's route lay through the centre of their distribution — the waters 

 around South-east Asia and Indonesia — I naturally seized the oppor- 

 tunity which this provided for collecting and observing sea snakes myself. 



I boarded the ship at Mombasa and cherished a hope of finding my 

 first sea snakes near the Seychelles, where one or two species have occa- 

 sionally been caught, as they have further south near Madagascar. My 

 hopes were doomed to disappointment. Despite a keen search all over the 

 shallow plateau on which this group lies we failed to catch one. Inquiries 

 among the local population confirmed the impression that sea snakes 

 here are rare, and that most people have never seen one. We thus obtained 

 corroboration of a strange feature in their geographical distribution: while 

 the eastern side of the Indian Ocean teems with them, only two species, 

 Enhydrina schistosa and Pelamis platurus, have succeeded in penetrating 

 beyond Arabia down the East African coast, though Pelamis has man- 



