A TASMANIAN SQUID, OR CUTTLE-FISH.
Giant species of squids have been recorded in which the shorter tentacles measured 12 feet, and the two longer ones as much as 30 or 40 feet in length.
In the Octopus and its allies the creeping-base, or foot, is prolonged round its margin into eight or more arm-like extensions. The anterior of these in the earlier phases of their development grow round and enclose the mouth, which consequently opens upon the centre of the locomotive surface. The arms of the octopus and other forms are in most instances provided throughout their length with complex sucking-disks, wherewith their owners can seize and retain their prey or walk with ease and celerity over the smoothest perpendicular or overhanging rock-surfaces. The octopus, as the type of its class, possesses yet another most effective locomotive organ. This is the so-called funnel, or siphuncle, a membranous tube connected with the capacious gill-cavity which is formed by a folding of the mantle on the under-surface. When at rest or moving leisurely, the water taken in through the pocket-like entrance to this cavity is discharged through the funnel without any particular effort. The animal can, however, at will leave go its attachment to the rocks, and propel itself swiftly through water by successive forcible expulsions of the water through the funnel. By directing the aperture of the funnel to the right or left, the creature can also direct its course in whatever direction it desires. When thus swimming, its translation is necessarily backwards. Another notable feature of the octopus is the "ink-bag," a huge gland secreting an inky-black fluid, which, as produced by the common cuttle-fish, constitutes the sepia of commerce. The contents of the ink-bag are discharged through the funnel at the will of the animal; as soon as the ink is brought into contact with the water, it becomes distributed through it in the form of a thick cloud, under cover of which the mollusc makes good its escape from any attacking enemy.
The octopus in British seas by no means attains to its maximum growth. Examples with arms from 2 to 2½ feet in length are accounted large specimens. In Mediterranean waters, however, these dimensions are much exceeded, individuals with arms 5 feet long, which are capable of covering a circular area no less than 10 feet in diameter with their fully extended appendages, being frequently recorded. In the West Indies, on the North-west American coast, and also in Chinese seas, similar, if not larger dimensions are attained by these creatures. That these monster octopods, or "devil-fish," as they are sometimes designated, prove a source of danger to human life has been abundantly demonstrated. Lurking, as is their custom, among rock-crevices, they seize hold of any moving object which approaches within reach of their extended arms. Bathers in this manner have been seized and drowned, it being impossible for even the strongest swimmer to free himself from the clutches of one of these animals, which, while retaining a firm hold on the rocks with a portion of its hundred-suckered arms, has entwined the others around its victim.
Photo by W. Saville-Kent, F.Z.S.] [Milford-on-Sea.
SHELL OF THE PEARLY NAUTILUS.
The inner lining of this shell is brilliantly iridescent.
The natural food of the octopus are crabs, lobsters, and their like; and in places like the Channel Islands, where the tide retires very low, leaving the rock-fissures inhabited by the molluscs more or less exposed, their presence may be often foretold by the accumulation of empty, broken-up crab-shells around the entrances to their retreats. In common with other members of its tribe, the octopus is furnished with a strong, horny, parrot-like beak, wherewith it can with ease break through the shells of its accustomed food. The year 1900 was remarkable for the extraordinary abundance of the octopus on the English south coast, the result of their collective depredations very seriously affecting the local crab and lobster fisheries. The pots laid down over-night, in place of yielding the following morning their customary quota of marketable crustaceans, were more often than otherwise found to contain nothing but broken-up shells and a loathsome "devil-fish."
The Squids and Cuttle-fishes, with their large lustrous eyes, are especially adapted for an open sea life, and for this purpose are furnished with lateral fin-like membranous expansions. A more important structural distinction is their possession of two supplementary appendages, which, usually retracted within special pouches when not in use, can be shot out to a length at least twice that of the eight ordinary arms. Both the cuttle-fish and the squid, or calamary, are also the possessors of an internal calcareous or horny shell which underlies and strengthens the upper-surface. The cuttle-bone used as a dentifrice and ink-eraser is the product of the first-named mollusc. The Ten-armed group, as it is named, with reference to the two supplementary arms, ten in all, possessed by its members, is notable for including species whose dimensions not only exceed those of any other invertebrate type, but whose fully extended length rivals that of the largest vertebrates. Giant squids, or calamaries, have been taken off the coast of Newfoundland, yielding, with their tentacular arms extended, a linear measurement of over 50 feet, associated with an estimated weight of as much as 1,000 lbs. There can be no doubt that these giant squids have in many instances furnished the basis of the oft-recurrent sea-serpent stories, more especially on those occasions where the supposed marine reptile and a whale have been reported as seen engaged in combat. As a matter of fact the sperm-whales habitually feed on deep-sea squids, and have been known, when mortally wounded, to vomit forth detached portions of these gigantic molluscs. The long tentacular arms of one of these monsters, thrown around the whale with which it had entered upon a death-struggle, might at a little distance be easily mistaken for some huge snake-like organism.