The eyes can discern, both in front, and in rear. Convexed, exterior, and en facettes, they can, at a glance, sweep almost the entire horizon.
The antennæ, the feelers, organs of touch and trial, of warning and of guiding, have the sense of touch at their extremities, of hearing and of scent, at their base. An immense advantage, such as we do not possess. How would it be if the human hand could hear and smell? How rapid and concentrated would then be our power of observation. Divided among three senses, each of which works independently of the other, our impressions are, for that very reason, very often inexact or evanescent.
Of the ten feet of the Decapodes, six are hands, hard, griping pincers, and, moreover, are, at their extremeties, organs of respiration. And in this last particular our singularly armed warrior, by a quite revolutionary expedient, solves the problem which so much embarrassed our poor mollusc; how to breathe, in spite of the shell. To this he calmly replies: "I breathe through hand and foot. This great, this fatal difficulty of breathing, which would so surely overcome me, I overcome by the very same weapon with which I smite, the very same implement by which I seize and masticate my food."
The chief and most potent enemies of the Crustacæ, are the tempest and the rock. Little in the deep sea, they almost constantly lurk along shore in waiting for their prey. Often, as they lurk there waiting for the oyster to open and furnish them with a breakfast, a hard gale drives them from their ambush, and then their armor becomes their fatality. Hard, and destitute of elasticity, it receives the full and unmitigated shock of every collision; dashed upon the rocks, they leave it, if alive, only with broken weapons and rent armor. Happily for them, they, like the Oursin, can replace an organ, lost or mutilated. So well do they know that strange power, that they voluntarily shake off a claw, if confined by it. It would seem that Nature especially favors servants so useful. To counterbalance the infinite fecundity of other species, the crustacæ have an infinite power of absorption. And they are everywhere; on every coast; ubiquitous as the seas themselves. The Vultures, and other carrion birds, share with the crustacæ the essential office of health preservers. Let some large animal die, and, on the instant, the bird above, and the crab below and within, are at work to prevent it from polluting the atmosphere.
The Talitre, that small and skipping crab that we might almost mistake for an insect, burrows in the sands of the sandy shores. Let a tempest drive a quantity of Medusæ or other such prey upon the beach, and you will immediately see the sands all in motion, and myriads of crabs swarming, leaping, hungry, and apparently determined to clear away the spoil before the next flood tide.
Large, robust, and full of wiles, the great crabs are a very combative race. So highly are they gifted with the instinct of war that they even resort to noise in order to intimidate their enemies; advancing to the fight they clash their claws together with a noise like that of castanettes. Yet, they are very prudent when they have to do with a stronger enemy. I remember to have watched them from the top of a high rock, when the tide was out. But, high above them as I was, they perceived that they were watched, and speedily beat a retreat; the warriors hurrying sidelong, as is their wont, into their secure ambush. They resemble Achilles far less than Hannibal. When they feel that they are the stronger, they will attack both the living and the dead, and the helplessly wounded man may well dread them. It is related that, on some desert isle, several of Drake's sailors were attacked and devoured by these greedy creatures.
No living creature can fight them with equal weapons. The gigantic Poulpe who should enlace the smallest of the crab family, would do so at the risk of losing his antennæ, and the greediest of fish would not venture to swallow so hard a morsel.
When the Crustaceæ are large they are the tyrants and the terror of both land and sea; their impregnable armor enables them to attack everything. They would multiply to such an excess as to disturb the balance of living creatures, but that their armour itself is their great peril and destroyer. Hard and inelastic, it will not yield to the increasing growth of the animal and thus becomes its prison always, and at certain periods its torture.
To find, despite this solid wall, the means of breathing, it is obliged to place the organ of respiration in that very organ, the claw, which it most frequently loses. To allow for the growth of its interior substance, it is obliged—most perilous obligation!—to submit that the hard cuirass shell shall at times be discarded; that the creature shall have its seasons of moulting; that the eyes, and the claws, and the tentacles, which supply the place of lungs shall suffer with all the rest.
A strange and pitiful sight it is to see the Lobster writhing, twisting, struggling, to get out of its too confining armor. So violent is the struggle that he sometimes actually casts off his claws. Then he remains soft, weak, exhausted. In two or three days a raw shell covers the naked body; but the Crab does not so easily repair damages; it takes him much longer to renew his armor, and during that time he is the victim of all that previously were his unspared and unpitied prey. Even handed justice now becomes terrible to him. The victims now have their revenge; the strong is subjected to the law of the weak; falls, as a species, to their level, and pays full share in the great balance between Life and Death.