When a porcupine wishes to attack an enemy, he rushes at it backwards, and usually leaves the enemy literally covered, like a living pin-cushion, with his spines. These animals have convex skulls, short tails, and live chiefly in the warmer regions of the Old World. Those of America are different in one particular—the soles of their feet are covered with hard, bone-like tubercles, instead of being soft and smooth; there are also a number of hairs that are intermingled with the spines. The Canada porcupine has more hairs than the American, and a shorter and stumpier tail.
Another animal whose methods of defence are by means of his spines, is the hedgehog. His spines do not terminate in sharp points, like those of the porcupine, but end in tiny knobs. These are placed beneath the skin, and are like pins stuck through a cushion. The hedgehog, like the porcupine, rolls himself into a ball when attacked by enemies, and he has the additional ability of throwing himself down a hillside, like a rolling ball, and thus escaping his enemies without injury to himself. It would seem that the hedgehog, rolled into a ball and covered with prickles, would be protected from all enemies. But this is not true, for the clever fox knows just how to make him unroll. This one secret of the hedgehog's weakness very often causes his loss of life. His weakness is a terror of being wet or dropped into water; and when the fox finds him all rolled up, he carefully rolls him into a pond of water and, when he unrolls, quickly drowns him. Notwithstanding the shortness of the hedgehog's spines, he is the most highly specialised of all spine-bearing animals. In the lower order of animals there are spiny mice and spiny rats, and even the horned toad uses his horns as a means of protection against his enemies.
One of the most peculiarly armoured animals is the horned lizard, commonly known as the "horned toad" of America. His body is covered with small spiny scales, while the chisel-shaped head has a circlet of miniature horns. These he uses when attacked by enemies to shield himself against bites and knocks. The Indians claim that if a snake swallows the horned lizard whole, the lizard will immediately work his way through the snake. This would not be without a parallel, however, for it is generally known that box-fishes, when swallowed by sharks, bite their way out!
Nature has been especially kind to horned lizards, and that is the reason there are so many of them. They well know the secret of the Gyges ring, and can put on the garment of invisibility in a very short time. They especially frequent the desert regions of the South and West; and those that dwell in black sandy regions are black; those of red clay regions are red; those of grey regions, grey; those from the variously coloured regions of blue and red are precisely the colour of the earth. But not satisfied with all their protections of armour and camouflage, they actually, when hard-pressed by an enemy, feign death, like an opossum! And if the enemy persists in his attack, and Mr. Lizard cannot escape, as a final effort he spurts tears of blood from his eyes. The Mexicans call him the "sacred toad." The phenomenon of blood-shooting has been explained in various ways, all of which seem equally unsatisfactory. So far it is one of Nature's secrets. Perhaps some day we may understand it.
The tortoises are among the best examples of creatures which to-day protect themselves with armour. They are, of course, reptiles, yet in the general formation of their armour, they are strikingly like armadillos. The tortoise has his armour so arranged over his body that it forms one big box. He draws his head and limbs into this whenever danger is near. In Texas recently I found a small land terrapin, and as soon as I came near, he closed his house. I picked him up, and then carefully laid him upside down on the ground, and stepped behind some nearby bushes to see what he would do. Immediately he poked his head out, and then his feet, and then he began to wave his feet wildly in air, and finally threw himself in the right position and hastened away through the grass.
The turtle protects himself in the same way, and draws his head, feet, and tail under his own house-roof where nothing can get him.
Lobsters and crabs are excellent types of armour-bearing animals. Lobsters wear marvellous coats of mail, very similar to those worn by human warriors during the age of chivalry. Their jointed structure assures them perfect ease and security. Crabs, however, believe, as the tortoise, in the strong-box protection. When resting, crabs tuck their legs beneath them, so as to shelter themselves under the hard covering. Upon crabs Nature has bestowed twin protective characteristics: namely, they are armoured, and also mimic their surroundings. The latter protection is especially needful, because certain big fishes, like the cod, are in the habit of swallowing crabs whole. In this case the armour is of no use, while the protective resemblance saves the crab.
To discuss in detail all the various kinds of armour and mail that the different groups of animals have used and developed for offensive and defensive purposes since the days of the prehistoric gigantic armadillos to the present, would require a book of itself. It is sufficient to know that armour and mail and spines are among Nature's most common forms of protection, and that each age develops new and ever more efficient methods of defence. This simply means that the age-long drama of evolution is always changing. Everything that is came out of that which was, and throughout the ages the ever-evolving organisms have been developing out of the past, that they might ever be new.