At intervals, for many years past, I have found the eggs of the Sepia and Loligo in early stages of their development, and have hatched them out, without any assistance from their parent, by merely suspending them in sea-water in a tank or tub, and changing the water frequently. The same also has been frequently done at the Brighton Aquarium. This having been proved and demonstrated by actual experiment, it is unnecessary to fortify facts by reasoning. But I have seen a branch of a tree or shrub, measuring more than two feet in height from the base of the broken stem to the upper part of its branches, and fourteen inches from side to side across the tips of the twigs, covered with the eggs of Sepia in single rows along them. I cannot of course, be certain that these were all laid by one female, but it is evident that one could not cover so great an area continuously as an incubator, and that, if it were possible, she would subject herself to unnecessary toil in so doing, seeing that they were all hatched in a tank, after having been for about ten days deprived of maternal care.
The young Sepia when born is much larger than a baby octopus or squid. It is of about the size of a rather small horse-bean. When about half developed, the little animal has the head and eyes disproportionately large, but gradually acquires a greater resemblance to its parent. If the black integument be removed, as one would skin a grape, it may be seen moving in the fluid which fills the egg. Cut down to the little living grape-stone under water, and away it will swim, with all its wits about it, and in possession of all its faculties, with as much facility and self-possession as if it had considerable knowledge of the world. It sees and avoids every obstacle, and if you take it out of the water, in your hand, the precocious little creature, not a minute old, and not sufficiently matured to leave the egg naturally, will spurt its ink all over your fingers. You may tame an old cuttle-fish, and it will learn to know that you are a friend, and intend to do it no harm; but the youngsters are as shy as human babies, and regard every one but their mother as an enemy.
The preference for the light, which I described as exhibited by the young octopus, appears to be common also to the young squid and cuttle-fish. The latter generally seek the surface of the water; sometimes swimming gently by means of the locomotive tube and the undulating movement of the marginal fins, and at others poising their bodies motionless, as if basking. The habit in these two families is not so surprising as it is in the young octopus, because the adult Sepia and Loligo are not cave-dwellers, but frequent the open sea, and often approach the surface.
Fig. 11. Spawn of the common Squid (Loligo vulgaris).
The spawn of the squid (Loligo vulgaris) consists of dozens of semi-transparent, gelatinous, slender, cylindrical sheaths, about four or five inches long, each containing many ova embedded in it, and all springing from one common centre, and resembling a mop without a handle. Johann Bodasch, Professor of Natural History at Prague,[22] calculated that one of these mop-like masses contained 39,766 ova; and by counting those embedded in ten of the long gelatinous, finger-like processes, and weighing them and the remainder, I have verified his estimate, and computed that in the specimen which was the subject of my investigation there were 42,000 perfect young squids. It is evident that comparatively few of them live to arrive at maturity, or the sea would teem with them; and in every existing aquarium it has been found impossible to rear the young cephalopods hatched there. I have never seen these “sea-mops” attached to anything, and the pelagic habits of the calamaries render it probable that they are left floating on the surface of the sea.
A remarkable organ with which some of the cephalopoda are provided is a sac, popularly called the “ink-bag,” in which is stored a deep black secretion, which they are able to employ at will as a protection from rapacious enemies. On the approach of a suspected foe, the animal discharges a quantity of this dense fluid, which renders turbid the surrounding water, and thus enables its owner to escape in the obscurity. There is a communication between this ink-bag and the funnel or locomotor-tube, already described; so that when the ink is ejected, it is forcibly emitted with the stream of water which produces its rocket-like, backward motion. The very effort for escape thus serves the double purpose of propelling the creature away from the danger, and discolouring the water in which it moves.
Oppian has well described this:—
“Th’ endanger’d cuttle thus evades his fears,
And native hoards of fluids safely wears.