FANG AND POISON

Evening Post, Volume CXVIII, Issue 13, 16 July 1934, Page 7

FANG AND POISON

DEFENCE OF ANIMALS

HOW THEY ARE EMPLOYED

. Poison is to some animals what teeth' and claws are to others. • It-is if anything a more effective instrument of combat, and one which provides many otherwise defenceless creatures with a sure means of holding their own (saya the "Manchester Guardian").

Not long ago there arrived at the London Zoological Gardens a,, consignment .of snakes whose specialty is spitting poison. Such is their mastery of this accomplishment that motor goggles have to be worn by those who tend them to protect the eyes, which appear to be a favourite target. A notorious offender in this respect is Binghal's snake, a South African species gifted with uncanny marksmanship.

Many people still imagine that the power of spitting poison i^ general among snakes and other reptiles, but this is as much a fallacy as the belief that the flickering forked tongue is a poison "fang." A similar act, though performed in a totally different way, has made the skunk notorious and secure from attack, for no.adversary will voluntarily face the stream. - of fetid fluid which this animal can emit.

After holding amphibians like toads and salamanders a milky fluid is' often observed on the hands. This issues from the glands which may be either distributed all over the skin of the body or localised in the form of warty excrescences. • The substance is not poisonous to man, but merely disagreeable and, in some cases, mildly irritant. Injected into the circulatory system of animals it may, however, prove exceedingly poisonous, affecting the heart and the nerve centres. That of I a South American amphibian is employed by the Indians to poison their i spears and arrows for killing monkeys in the same way that the Bushmen utilise the venom of the puff-adder.

MECHANISM OF FANGS.

Lethal weapons designed to inflict a direct flesh wound occur chiefly among reptiles and insects. Snakes can be roughly divided into venomous and nonvenomous species, but as there are no common characters by,-which t6 distinguish the one from the other, it is policy, to regard, all as suspect. The simple • but terribly efficient mechanism of a snake's poison apparatus can be explained in a few words. In. the great majority of. cases the fangs are two large backward-curved teeth near the front of the upper jaw.' An ingenious hinge allows them to lie flat when the mouth is closed and to spring erect as it opens. Ttie pressure of biting causes the poison, a modified'saliva, contained in glands near the eyes, to pass into the wound by way of these specialised teeth. To make .this possible each tooth has either a groove on its front side or a narrow canal through, its interior along winch the poison travels. In the latter ease the aperture of the canal is to one side of the tooth, a little below the'point, exactly as in a hypodermic syringe; This lessens the liabilityjo blockage and enables the extremity of the,tooth to continue to a fine point. Sometimes the fangs get broken, but there are always reserve teeth ready, or nearly ready, to take their place.

Venom is a yellowish fluid, usually odourless and tasteless, and possessing remarkable properties. It can be frozen or dried without losing potency, and in some cases no harm results from swallowing it.... The. effects of snakebite vary greatly. Different kinds .of animals react in different ways-to-the same kind of-poison: -Some-are completely immune from its action; and, in fact, prey upon snakes. The secretary bird is an example, and also, the Mng cobra, or hamadryad, ■■ which; feeds exclusively upon other snakes. •.- •:.:•■>■•■

insect stings:

,--The poison weapons; of-insects eanrbe viewed 'with less concern',- for, as a rule, the most human beings suffer ifroik them is acute- '• discomfort.' Diseases communicated by insects are: die 'to bacterial infection following aliite/and not to the sting. Although.commonly nsed defensively, the power of. inflicting a wound and introducing" poison is employed by many insects as a means "of securing prey. Generally the poison consists of formic acid mixed with, other irritants, and it is ejected by muscular contraction through a complex piercing organ, or sting, at the end of the abdomen. And since this sting appears to have been derived from the egg-depositing organ (ovipositor) it follows that only females are in possession of it. Drones, or male bees, for example, have no stings. Many insects have what looks like a. dangerous ■ sting at the hinder end i of-the body.. No alarm need be felt ! concerning this, because stings are not advertised in this way, but discreetly hidden.^ Such appendages are harmless ovipositors designed to penetrate crevices or act as. drills. Every year consternation is caused by the appearance of a large insect of the size and colour of a hornet which is .brought; to this country in imported timber, ■ It is armed with a formidable-looking in«strumeht, nearly an inch in length, an<J is often slaughtered and sent to th» local museum for identification. Thi» is a giant sawfly and the. supposed stinf is an .ovipositor. Hunting wasps possess remarkabJr power to control the action, bf'theil poison. These insects- capture '.living caterpillars and other insects, and store them in a chamber as leady-to-hand food for their young grubs, which share the same apartment. ' But first of all t.he.preyis stung ; not in a haphazard fashion., but scientifically by one or more thrusts of the sting in various parts of the body. The result is not death but general paralysis, the effect of which is to render the victim inactive and therefore unable to molest the tiny-grubs. In. this state it may live for weeks to provide a larder for the growing family. " '

LEGS AND SPIKE.

Various structures of the body have, |by modification, come to function as ; poison weapons. In centipedes it is the first pair of legs that are so developed. These are claw-like and have at the tip an opening communicating with a poison, gland. Some of the tropical species are a foot in length and are able to inflict a ''bite "which may' be fatal to man. Scorpions carry at the end of the long flexible body a stout spine supplied with poisoa generated in the swollen terminal segment of the body. The curved shape of the spine appears a little curious until it is realised_ that the creature arches its tail over its body and strikes forward at the prey, which is held in. front of the head by the great pincer-likf claws. ■