This section is from the book "General Outline Of The Organization Of The Animal Kingdom, And Manual Of Comparative Anatomy", by Thomas Rymer Jones. Also available from Amazon: A General Outline of the Animal Kingdom and Manual of Comparative Anatomy.
(1503). We now arrive at the highest order of Mollusca, composed of animals distinguished by most strange and paradoxical characters, and exhibiting forms so uncouth, that the young zoologist who for the first time encounters one of these creatures may well be startled at the anomalous appearance presented by beings so remote in their external construction from everything with which he has been familiar.
(1504). Let him conceive an animal whose body is a closed bag, containing the viscera connected with digestion, circulation, and reproduction, furnished with a head and staring eyes - that upon the head arc supported numerous and complex organs of locomotion, used as feet or instruments of prehension - moreover, that in the centre of the locomotive apparatus, thus singularly situated, is a strong and sharp horny beak resembling that of a parrot - and he will rudely picture to himself a Cephalopod, such as we are now about to describe.
(1505). The Octopus vulgaris, or common Poulpe, represented in the next figure, will serve as an example calculated to prove, we apprehend, that the above is no exaggerated statement; and should the student unexpectedly observe an animal of this kind walking towards him upon the beach in the position there delineated, his curiosity would doubtless be excited to learn something of its habits and economy.
(1506). Yet not only can the Poulpe walk in the manner exhibited in the subjoined figure (fig. 280), but it is well able to swim, if occasion require, - the broad fleshy expansion that connects the bases of its eight legs being fully adequate to enable it to adopt such a mode of progression; for, by vigorous flappings of this extensive organ, the animal actively impels itself through the water in a backward direction and shoots along with wonderful facility.
(1507). The feet or tentacula appended to the head are not, however, exclusively destined to effect locomotion: they are used, if required, as agents in seizing prey, and are of so terrible a character, that, armed with these formidable organs, the Poulpe becomes one of the most destructive inhabitants of the sea; for neither superior strength nor activity, nor even defensive armour is sufficient to save its victims from the ruthless ferocity of such a foe. A hundred and twenty pairs of suckers, more perfect and efficacious than the cupping-glasses of human contrivance, crowd the lower surface of every one of the eight flexible arms. If the Poulpe but touch its prey, it is enough: once a few of these tenacious suckers get firm hold, the swiftness of the fish is unavailing, as it is soon trammelled on all sides by the firmly-holding tentacula and dragged to the mouth of its destroyer. The shell of the Lobster or of the Crab is a vain protection, for the hard and crooked beak of the Cephalopod easily breaks to pieces the frail armour; and even man himself, while bathing, has been entwined by the strong arms of gigantic species, and struggled in vain against a grasp so pertinacious.
Fig. 280. The Poulpe (Octopus vulgaris).
(1508). In the genus Octopus the arms are only eight in number, and nearly of equal length; but to the Calamaries (Loligo) and other genera an additional pair is given, which, being prolonged considerably beyond the rest, are not merely useful for seizing prey at a distance, but become convertible to other purposes, and may be employed as cables whereby the Cephalopods so furnished ride securely at anchor in a tempestuous sea, - the suckers being placed upon an expanded disk, situated (fig. 282) at the extremity of the elongated tentacula, and thus rendered capable of taking firm hold of the surface of a rock or other fit support. The posterior extremity of the body is, in such forms, generally provided with two broad muscular and fin-like expansions (fig. 282), evidently adapted to assist in sculling the animal along.
(1509). Wonderful as are the provisions above described for ensuring food and safety to these formidable inhabitants of the sea, it is only by an attentive examination of the individual suckers, so numerously distributed over the tentacula, that the reader will fully appreciate the mechanism we are so inadequately describing. Machines of human construction admit of being variously estimated, as they are found to be more or less adapted to accomplish the object of the contriver; but in estimating the works of the Deity all degrees of comparison are merged in the superlative; everything is best, completest, perfect.
(1510). Examine any one of these thousand suckers: - it is an admirably arranged pneumatic apparatus - an air-pump. The adhesive disk (fig. 281, a) is composed of a muscular membrane, its circumference being thick and fleshy, and in many species supported by a cartilaginous circlet, so that it can be applied most accurately to any foreign body. In, the centre of the fleshy membrane is an aperture leading into a deep cavity (b, b), at the bottom of which is placed a prominent piston (c), that may be retracted by muscular fibres provided for the purpose. No sooner therefore is the circumference of the disk placed in close and air-tight contact with the surface of an object, than the muscular piston is strongly drawn inwards, and, a vacuum being thus produced, the adhesion of the sucker is rendered as firm as mechanism could make it.
(1511). Yet even this elaborate and wonderful system of prehensile organs would seem, in some cases, to be insufficient for the purposes of nature. In the powerful and rapacious Onychoteuthis (fig. 282), the cupping-glasses which arm the extremities of their long pair of muscular arms are rendered still more formidable; for from the centre of each sucking-cup projects a strong and sharp hook, which is plunged by the action of the sucker deeply into the flesh of struggling or slippery prey, and thus a firm and most efficient hold upon the seized victim is secured.