Sea snakes’ scales.
From the Thanatophidia.
A further facility to their agile and graceful movements in the water are their smooth, non-imbricated, or only slightly imbricated scales. These, though mostly hexagonal, and laid side by side, different from those of land snakes, yet vary much in size and form; and the head shields particularly are so abnormal, that, as Günther affirms, you can tell a sea snake at once by them (see illustrations, chap. xviii.).
To distinguish a pelagic from a fresh-water snake is, however, far easier than to distinguish species among themselves. They present great varieties of form and colour, but the transitions are very gradual, and the female is generally larger than the male, and sometimes of a different colour, which adds to the difficulty.
They are all viviparous, and produce their young in the water, where the little ones are at once able to take care of themselves, and feed on small fish or molluscs. The full-grown Hydrophidæ feed on fish corresponding with their own dimensions, and swallowed head foremost. Even spiny fish are managed by them, notwithstanding that they have a smaller jaw than most land snakes. Being killed by the poison of the bite on being caught, Günther explains, the muscles of the fish are relaxed, and the prey being commenced at the head, the armature does not interfere, but folds back flat as the fish is gradually drawn into the jaws.
An interesting study to the lover of nature it is to watch the wonderful movements of these sea reptiles. Swimming and diving with equal facility, flashing into sight and disappearing again in twos or scores, or in large shoals, pursuing fish, many of them of bright colouring, they offer constant amusement to the beholder. Sometimes, when the sailors are throwing their nets, they disappear beneath the waves, and are no longer seen for half an hour or more; when presently, far away from the spot where they vanished so suddenly, up they come to the surface again, to sport once more, or take in a fresh supply of air.
Pity they possess such evil qualities to blind us to their beauties, for they rank among the most venomous of serpents. They belong to the sub-order of venomous colubrine snakes, or Ophidia colubriformes Venenosi, those which outwardly have the aspect of harmless snakes, while yet furnished with poison fangs. In the chapter on Dentition, these distinctions, facilitated by the illustrations, are more fully explained; here it need only be said that though they have smaller jaws and shorter fangs than many other venomous snakes of their size, the virus is plentiful, and so active that the danger from the bite is great. All the pelagic serpents have also a few simple teeth behind the fangs; therefore, as Fayrer warns the natives, it does not do to trust to the appearance of the wound, which, though looking like the bite of a harmless snake, would demand immediate remedies. A certain conviction of danger is that the bite being inflicted in salt water, would leave no doubt as to the nature of the snake. Even a painless wound it is not safe to trust; and Sir Joseph Fayrer gives several such warnings among his cases of bite from sea snakes, two of which I will quote.
Captain S——, while bathing in a tidal river, felt what he thought was the pinch of a crab on his leg, but took no notice of it, and after his bath called on some friends, being to all appearance exceedingly well. He remained about an hour, playing the concertina to amuse the children, and declaring himself never in better health. In about two hours, feeling strange symptoms of suffocation, enlargement of the tongue, and a rigidity of muscles, he sent for a doctor, but still having no suspicion of danger. The next morning a native detected the peculiar symptoms which usually follow the bite of a sea snake; and Captain S——, then examining the foot which the supposed crab had nipped, found marks of fangs no bigger than mosquito bites on the tendon Achilles near the ankle. Immediate steps were taken, and remedies applied which seemed to promise favourable results for a time; but in the evening of the third day the victim was seized with spasms, and died, seventy-one hours after the accident. In this case, owing to the sound health of the captain, and no local pain ensuing to warn him, together with the stimulants and remedies applied, and the bite being where absorption was slow, his death was protracted; otherwise death often occurs within twenty-four hours from that species of snake.[75]
The second case was that of a man who was bitten in the finger by a sea snake, and thinking lightly of it, used no means whatever to arrest the poison, and was dead in four hours.
In some cases the victim becomes quickly insensible, when, if no aid is near, he never wakes to consciousness. Immediate stimulants revive the patient, and if he can be kept awake, these, with local applications, at once applied, may save his life. ‘Hope itself is a powerful stimulant,’ adds the learned experimentalist.
Many other cases are given by Fayrer of bites by sea snakes, some of which yielded to remedies and others were fatal; but for these the reader is referred to the Thanatophidia.