94 



SEA SNAKES 



would have only the yolk of the egg on which to grow and so would 

 never attain to so considerable a size. 



The different coloration of the young is probably due to their different 

 mode of life. Both forms of coloration — the alternate dark and light 

 bands in the young and the dark back and light belly of the adults - — are 

 good examples of protective colouring. The light and dark bands cause 

 the animal's contours to dissolve; to break up, as it were. This form of 

 mimicry will be especially effective among algae or branched corals. The 

 dark back and light belly are a form of camouflage frequently met with 

 in many pelagic fish, like, for example, herring and mackerel; as such 

 creatures will normally be illuminated from above, the belly will appear 

 darker, the back lighter, than in reality they are, with the result that the 

 animal will seem to be uniformly coloured. It can therefore be said, 

 with a fair amount of certainty, that the young frequent the coastal sea- 

 weed zone or coral reefs, while the adults swim in deeper water. A close 

 study of the biology of sea snakes will doubtless confirm this theory. It 

 is a curious fact that the adults usually retain the coloration of the young 

 on the tail (see Fig. p. 95). This circumstance would seem to invalidate 

 the theory just advanced, but in fact it provides the best conceivable 

 confirmation of it: the tail is held vertically when the snake is swimming, 

 and so, at best, it would serve no useful purpose to have it coloured like 

 the body. 



I indicated in the introduction to this chapter that sea snakes are 

 hardly likely to have provided the model for the countless reports of the 

 Great Sea Serpent. There are many reasons why this is so, including the 

 one that no sea snake is ever longer than three metres and most are only 

 about one metre long. The great majority of accounts of sea serpents 

 also come from the Atlantic, where there are no sea snakes. Moreover, 

 as already stated, all sea snakes with the exception of one small species 

 occur quite near to the coast, while sea serpents are typical ocean-dwel- 

 lers. Consequently, we must look to other zoological groups for the model 

 of the great sea serpent — if there be any such. 



Although this "exoneration" takes away some of the romance of sea 

 snakes, this little group of animals, by its interesting adaptation to a 

 new environment, is an absorbing subject for study. Several attempts have 

 been made to obtain some specimens for the Danish Aquarium, and we 

 also tried to do so. All attempts so far have failed owing to difficulties of 

 transport. Sea snakes suffer from long transport over land, but it should 

 be possible to bring them by air. This short chapter may suitably close 

 with the hope that the attempt will one day succeed, so that the general 



