The Sepiadæ have eight arms rising from the crown of the head armed with four rows of suckers, two long slender tentacles with broadly-expanding ends, and stalked suckers; eyes moving in their sockets, and body broadly ovate in Sepia.
If we study the general aspect of the animal more closely, we find that the tentacles—which serve at once as organs of locomotion for swimming, for creeping, and as prehensile organs for seizing and retaining its prey—are conical, very long, and all of the same form. Each of them has towards its axis a longitudinal canal, which encloses a great nerve, which is also surrounded with muscular fibres, arranged in rays. The suckers, already described, occupy all the internal surface of the eight tentacular arms, which are arranged in two rows, having the form very nearly of a semi-spherical capsule. Of these suckers, each arm of the cuttle-fish carries about two hundred and forty, the total number being nearly a thousand. The mouth we have already described, in Dr. Roget's words: "The teeth move vertically, much as the cutting edge of the two blades of a pair of scissors move upon each other, tearing the prey by the assistance of their hooked terminations."
The tongue is covered on its upper part by a thick horny bed, bristling in the centre with a series of recurving teeth, while its edge is armed with three other erect teeth, which are slender and hooked. The œsophagus is long and slender. At the abdomen the gullet expands into a sort of frill, to which succeeds a gizzard, with strong fleshy walls; and, finally, a very short intestine, which directs itself forward, terminating on the median line of the body. Towards the anterior parts is a cavity, of which a few words must be said. It occupies the free space comprised between the exterior surface of the abdomen and the internal face of the mantle; and here the respiratory organs, namely, the branchiæ, are lodged. Here, also, are the reproductive and excretory organs.
The branchiæ, which are two in number, are voluminous, but short, tufted, and leaf-like. The branchial cavity can dilate and contract itself alternately. It communicates externally by two openings: the one, fashioned into a cleft, receives, while the other, which is prolonged into a tube, serves to eject, the water, and becomes a powerful organ of locomotion.
The inspiration of the animal is thus made by a cleft in the mantle, and expiration by the tube: the renewal of the respirable liquid acts as a sort of sucking and forcing pump, at the surface of the lamellar branchials. The cuttle-fish, in short, will be at no loss to reply to the question of the Don Diego of Corneille—
"Rodrique, as-tu du cœur?"
for they have three hearts. The two first are placed at the end of the branchiæ. With each beat of the pulse the venous blood is brought from all parts of the body, and propelled through each gill or branchiæ. Vivified by respiration in the internal tissue of the branchiæ, it is carried by the veins into the third heart, situated upon the median line of the body; and now the regenerated fluid is again distributed throughout the rest of the economy.
Not to oppress the reader with anatomical details, we shall just remark that the gaze of the cuttle-fish is decided and threatening. Its projecting eyes and golden-coloured iris are said to have something of fascination in them. The animal seems able even to economise the power of its glance, being able to cover its eyes from time to time by contracting the skin which surrounds them, and bringing the two translucent eyelids with which it is furnished closer together.
The cuttle-fishes are essentially aquatic and marine animals. We find them in every sea in all parts of the world; but they are most formidable in warm countries. They have a great predilection for the shore. During their youth they associate in flocks; but with age they fly from association, and retire into the clefts and hollows of the rocks. The old cuttle-fish is only found in rugged and rocky places, bristling with naked, pointed rocks, which have been worn by the waves, but generally in places only a few feet below the level of low water. "How often," says D'Orbigny, "have we not observed the cuttle-fish in his favourite retirement! There, with one of his arms cramped to the walls of its dwelling, it extends the other towards the animals which pass at its gate, embraces them, and by its power renders useless all their efforts to disengage themselves."
If we observe a cuttle-fish when it is what may be called walking, either on land or at the bottom of the sea, it will be seen to walk on one side, its head downwards, its mouth touching the ground, the arms extended and grappling some supporting object, and drawing the body forward; at the same time the arms at the opposite side are contracted and folded up, so as to assist by a contrary movement. On shore the movement of these animals is very slow. On the other hand, they swim very rapidly, assisted by all their arms, and aided by the water ejected from the locomotive tube, their movement being most frequently backwards, the body first, the six superior arms placed horizontally, the two others brought together above: the first help to sustain them in their horizontal position, the last to guide them, inclining to the right or left as the animal changes its direction.