Nature’s Touch-Me-Nots

New Zealand Graphic, Volume XLI, Issue 3, 15 July 1908, Page 51

Nature’s Touch-Me-Nots

NATURE is no haphazard experimenter. She is striving to promote the strength and fitness of her children, and by the process which we term “natural selection” is constantly weeding out the weaklings amd evolving more perfect types. But Nature is not needlessly changeful. When she has discovered a good device she repeats it over and over again. A striking example of this is seen in protective prickles. Nature seems to have proved that under certain conditions prickles form the best possible protective armament, and she has emphasised her discovery by an enormous number of instances, each brought through a different channel of development to the same conclusion. In the plant world, as everyone knows, prickles are common in the extreme; while, with the exception of birds, every important group of amimals possesses its spiny representaThe hedgehog is a well-known type of protective prickliness, and its habit of rolling itself into a ball when alarmed must be familial* to all. 1 his action is made possible by its thick layer of subcutaneous muscle, the panniculum caoiosus, which is more developed than in the case of any other animal. The young of the hedgehog, when born, have the. prickles soft and- white; but soon after exposure to the air they harden and become effective weapons. The widely distributed porcupines, which get their name from the French porc-epin, or . “spiny pig,” form another interesting group of prickly The porcupine is a formidable antagonist, rattling its quills and running backward at the enemy, and will often succeed in driving off a jaguar intent upon its destruction. Mammalian prickles are really tightly packed masses of hair. This is well shown in the accompanying photograph of a series of specimens selected from a porcupine skin, showing the complete gradation from an ordinary hair to a perfect, sharp-pointed quill. (Fig- 8 -) , i Passing over the birds? whose marvellous powers' of .flight and diving.seem to render any highly specialised protective devices unnecessary, we come to the reptiles. Of these the armour* plating of the tortoises and turtles, and the venomous means of the snakes are all-sufiieiem safeguards. But among the more vulnerable* lizards we find ■ numerous examples of protective prickliness. One of the most striking is the Australian moloch, termed the “thorny devil” by the early settlers. This remarkable creature is about eight inches in length, and its ekin is studded all over with sharp, conical thorns. The moloch is very sluggish in its habits, feeding mainly upon ants, for which it lies in wait. One would imagine it to be exposed to continual attack from birds and rapacious animals; yet no animal is more perfectly immune. Its prickles are its safeguard. Equally well protested hilt* perfectly harmless lizards are the so-called “horned toads!’ of California-and Mexico. About twelve species of these qnaint-looking creatures are known, all being alike in the possession of a formidable array of spines—several long ones at the back of the head, and a vast number of Ipsser prickles all over the back and* limbs. (Fig. 12.) ' t i Of fisheer »-larg.e juunber are protected from hostile attack by a covering of prickles. By far the most curious examples are the globe fishes, or “sea-hedge-hogs.”-* The extreme length of the globe fish' is something less than two feet. It has thick lips and goggle eyes which gave it the appearance of a goodnatured countryman. Courage it seems to.lack, and. one might suppose that such a simpleton would fall an easy prey to the first shark or dogfish it encountered. Yet the globe fi,sjl is-able to take care of itself. It, never, under any circumstances, attacks the enemy, yet it is always ready to receive him in a suitable manner should he provoke hostilities. Det us suppose that a shoal of globe fishes is swimming tranquilly in the clear waters when it is suddenly surprised by a hungry shark. Of course the little fellows scuttle hither and thither in uncontrollable alarm. But the shark, poising himself upon his powerful tail, leisurely singles out one of the flee-

ing globe fishes, and sets out in pursuit. Now although the globe fish is a good swimmer, it is no match for the shark. The chase is in every way unequal, and can have but one ending. Within a few minutes of its commencement the shark must overtake the globe fish. But the quarry is well aware of its danger. It makes a bee-line for the surface, and as soon as it gets there begins to take in great gulps of air. Then a strange thing happens. The fish that only a moment before was thin and small begins to grow stouter and stouter, until, like the.frog in the fable, it seems in danger of bursting. It stops inflating itself, however, just in time to avert this catastrophe. But its skin has become as taut as drum-head, anil the whole of its body is covered with sharp, erect prickles. It has become a sea hedgehog, and the hungry shark which comes surging through the water dares not touch it, but turns tail in search of something more eatable. Unlike its land prototype, however, the sea hedgehog is unprovided with a special muscle for erecting its prickles, so when danger threatens, it has recourse to the mechanical method * f inflating the whole body with air. or with water, if it cannot reach the surface quickly. In the sea, prickliness is a very common method of especially among the smaller ami more persecuted denizens. A numbs? of large fishes, such as the plaice and cod tribes, pass much of their time saarrikig for tfbsJiH-fisli, upon which they fead-greeoHy.. The plaice has particularly good tevih, which are strong and blunt.

It goes nosing about in the mud of the sea-bottom, turning up cockles, razorshells and clams, the shells of which it cracks as easily as a schoolboy cracks a hazel nut, and feeds upon the mollusk within. But certain species of shell-fish furnished with prickly shells, seem to object to being cracked in this manner, for, when a hungry fish, rooting in the mud, comes in contact with one of these, it gets nasty prick on the nose. Naturally, the finny searcher hastily abandons investigation in rl.is particular direction, and the prickly mollusk is left uncracked and uneaten. Similarly, many crabs, shrimps, and lobsters are protected by .an array of spines and prickles. Crabs are much relished by certain fishes. As many as a dozen have beer, found in the* stomach of one big cod. These, however, were a smooth-backed species, and a cod would never dare to swallow one of the thornbackcd crabs, of which numerous kinds are found in various quarters of the globe. Before leaving the ocean, the seaurchins, or must be mentioned, for, with the hedgehog, the globe fish, and the thorn-backed crab, they rank among the most prickly creatures known. They are enveloped in a wonderfull shell, or test, composed of a great number of accurately fitting plates. The test is covered with needle-pointed spines, in some, species these spines being eight or ten inches in length. Tims, the urchin dwells within a home the walls of which . ir.i’.y be eaid to bo guarded by scores of permanently fixed bayonets. The world of insect, life sunnlies us with myriad examples of protective pricklines?. Many of the big insects, such as species from Now Guinea, are simply beset with spines. Not a few caterpillars. too, are protected by closely set stiff heirs which correspond to the

prickles of bigger animals, and are probably quite as effective for repelling small birds and lizards, the chief enemies of the caterpillar tribe. Some of the most remarkable insects yet discovered are certain Brazilian bugs, known as Umbonia spinosa. E.-ch insect is an exact imitation of a single large thorn, such as is seen upon the stems of roses and other plants. This deceptive aspect is gained by a hard shield which completely covers tl.e insect’s be. !y and wings, and under which its legs are drawn when it is at rest. Turning from the animal to the vegetable kingdom, we still find prickliness a common means of protection. Sometimes wc see sharp spines, which are to be regarded as modifications of branches, of leaves, or of parts of leaves. In other instances we find .plants protected by true thorns, which are really massed vegetable fibres or hairs, and arc therefore analogous to the quilh of the mammalia. The main object of vegetable prickliness is, of course, to defeat the attacks of browsing animals. The cacti are. perhaps the most iiF foresting of all prickly plants. Here thO sharp spines are to bo regarded as the remains of denarted haves, although in the cacti the leaf functions arc delegated to the swollen stalks, the spines being wholly protective. We have all admired the beautiful Howers and have marvelled at the quaint shapes of cacti, but to understand thesU plants it is necessary to call to mind thfi conditions under which they grow a up flourish. Probably no plants have tlj contend with mere adverse circumstani cos. Typical of the arid districts Central America, cacti must keep greefl and fresh under a scorching sun through long periods of complete drought. Thifl they manage to do by making them sei veO into what are really water cisterns. A

BZcius is just a thick, juicy mass of green •ells, storing suflicient water to enable it to flower and perpetuate its kind. But in a region where water is a luxury, its possession constitutes a real danger. The icacti have, as it were, “cornered” water, •nd have thus become objects of envy to thousands of thirsty creatures who would like to gnaw and suck and bite at their juicy stems. “Such treatment would, of Bourse, mean death to the cacti; and in Order to protect themselves and tlieir water from assault, they have acquired the formidable array of spines, and are thus able to flourish under conditions Which would speedily annihilate almost al! other kinds of vegetation. Flowers are often protected by prickles, as in th ecase of the familiar thistle, or the teasel; while fruit capsules, such as those of the horse-chestnut and many exotic kinds, are also spiny. Did space permit, dozens of other instances of protective prickliness might be cited. The above examples, however, are sufficient to show how widely Nature has employed this particular means of defence.