No. 5 (1921) MADRAS Aquarium 61 



the prey protrudes from the snake's mouth. They are fond of 

 sardines, but spiny fishes they generally avoid. 



A single small fish, one of the sea-perches, lives unmolested with 

 these deadly snakes, and unconcernedly snaps up morsels of food 

 from amongst their w^rithing coils at feeding time. 



The colouration of the skin is generally inconspicuous, but 

 one of the most deadly, Hydrophis spiralis (Tam. Kadal sarai), 

 has developed a livery of black and golden chequers that renders 

 it most conspicuous; this is generally believed to be an instance 

 of warning colonratioi/, a sign to any large predaceous fish that the 

 wearer is dangerous ; the value of this colouring is mutual — it 

 prevents both creatures losing their lives, for though a shark or 

 muraena may swallow and kill the snake, the latter would certainly 

 inject a fatal dose of venom into the attacker before it died. 



Sea-snakes are often plagued by the settlement upon their body 

 of numbers of both acorn and stalked barnacles. The former of 

 these pests are , closely related to the little conical barnacles 

 that often render rocks near high-water mark so painful to the 

 barefooted visitor to the sea-side. Although they look more like a 

 conical shellfish — ^a limpet with the apex of its shell cut off — in 

 reality they are relatives of the prawns and sandhoppers as they 

 belong to the same group, called in science Crustacea. The young 

 of these acorn barnacles swim free in the sea for some days before 

 they settle down and attach to some solid body — rock, sea-snake, 

 turtle or even whale. The rest of their existence is spent in the 

 same position ; they exchange the pleasures of an unfettered life in 

 the sea for the comfort of an ignoble but safe lodgment upon 

 the body of some other animal (in this case) whose movements give 

 tlie uninvited guest continual opportunity to capture food from the 

 water around. The stalked forms are related similarly to the 

 well-known ship-barnacles often found in myriads attached to the 

 bottom of a ship that has returned from a long voyage. 



Mure fortunate than turtles and whales, sea-snakes are able 

 periodically to rid themselves for the time being of these unwel- 

 come guests, for like land-snakes those of the sea shed their skin 

 from time to time. As the time to do this approaches, a sea-snake 

 becomes lethargic, floating passively just under the surface of 

 the water. When in a thoroughly healthy condition as they 

 now are these snakes shed their old skin in one entire piece ; 

 previously when in a state of starvation, the operation was tedious, 

 the skin coming away in shreds. 



