SNAKES AND THEIR PREY

Southland Times, Issue 18973, 21 June 1923, Page 9

SNAKES AND THEIR PREY

METHOD OF SWALLOWING. LONG FASTS BY PYTHONS. Snakes and some popular falacies on this always fascinating subject are dealt with b> Mr R. I. Pocock in a recent article. After alluding to the antipathy felt by many people to reptiles, he mentions some ancient fables respecting enormous snakes, and describes the way in which the actual pythons and anacondas of Malaysia and South America deal with their prey. Huge as these reptiles are, their heads are comparatively so small and their necks so narrow that you would not think them capable of swallowing anything bigger than a rabbit. Although their capacity in that respect has been absurdly exaggerated, they can swallow animals of the size of pigs, goats, and the smaller sorts of deer, and the mechanism by which they do it is very curious.

The victim is caught by a driving stroke of the snake’s head, which moves like a streak of lightning. Almost simultaneously with the head stroke the body of the snake encircles that of its prey, which lies helpless in the muscular coils. Sometimes the victim dies quickly owing to the constriction stopping ita breathing; but the snake’s sole purpose is to hold it securely so as to prevent all chance of escape and to «void all risk of injury to itself if its prey perchance be armed with claws or dangerous teeth. In the case of small, defenceless, prey, the python frequently pay little heed to constriction, and I recollect as a boy seeing the hind -legs of a rabbit, which had been quickly swallowed, actually kicking in a python’s mouth before they followed the body and head down its throat.

Assured that its prey, whether alive or dead, is powerless, the snake seeks for its head, and, taking hold of it, starts to feed; and you will understand, that the choice of the head to begin upon is dictated by the instinct to avoid the difficulty of swallowing against the “lie” of the hairs—or fenthere, in the case of birds. If you carefully watch the action of the snake’s mouth, you will see how the swallowing is effected. In the first place, the lower jaw not only comes downwards, but spreads sideways, so that the gape is simultaneously deepened and widened; and this expansion sideways is made possible by the right and left bones of the lower jaw being fastened together in the middle of an elastic band or ligament, which allows them to separate, and are not joined together as in other reptiles, and in birds and mammals. This is the mam factor that gives the necessary stretch to the mouth. A contributory factor is the mobility of the bones of the upper jaw, which, like the lower jaw, carry hooked teeth, and are movably jointed to the skull. The action of the upper jaw in swallowing is a steady and orderly, but slow, progression, first one side, then the other, moving forwards. When the right side has got a firm grip with the teeth, the left is advanced and takes hold; then the right is brought into action again, and so on alternately, the snake’s jaws by that means slowly travelling over the victim’s head. As soon as the head of the latter reaches the back of the snake’s mouth, the muscles of the throat come into operation in the ordinary way and aid the process of swallowing. The throat and body are in their way as distensible as the mouth. The skin is very elastic, and the ribs, which run alLdown the sides, are not fastened to a breampone, as in us; and their upper ends are so jointed to the backbone that they can be lifted to give room for the throat and stomach to expand; and in a snake that has recently fed the position of the swallowed carcase is indicated by a huge swelling, which, as digestion proceeds, gradually subsides, and in a few days disappears altogether. A good meal will last a snake a week or more, but their capacity for fasting is not the least remarkable thing about them. An Indian python in the Zoological Gardens started to eat pigeons, after obstinately refusing to feed for very nearly two and a-balf years. But the record is held by Paris, where a python voluntarily fasted for over three years!