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Cuttle-Fish

CUTTLE-FISH. The more familiar and conspicuous types of the molluscan class Cephalopoda (g.v.) are popularly known in English as cuttle-fish, squid, octopus and nautilus. The first of these names (from the A.S. cudele) is applied more particularly to the common Sepia (Fig. i), characterized by its internal calcareous shell, sometimes known as cuttle-bone, and its ink-sac, the contents of which have been long in use as a pigment (sepia). The term squid is employed among fishermen for the ten-armed Cephalopods in which the shell is represented by an uncalcified flexible structure somewhat resembling a pen. Hence in Italian a squid is called calamaio, from calamus a reed or pen, and in English the similar term calamary is sometimes used. Like the Sepia, squids also possess the ink-sac, whence they have sometimes been called pen and ink fish, and in German both Sepia and squid and their allies are known as Tinten-fische. The squids have generally softer and more watery tissues than the Sepia, but the former term is not in general use, and the distinction not generally understood. The term cuttle-fishes is sometimes extended to include all the Cephalopoda, but as the peculiarities of the remarkable shell of the true nautilus, and those of the shellless Octopoda are widely known, we shall consider the name here as applying only to those forms which have ten arms, an ink-sac, an internal shell-rudiment, and only one pair of gills in the mantle cavity. Technically these form the sub-order Decapoda, of the order Dibranchia.

The cuttle-fishes are characteristically swimming animals, in contrast with the octopods, which creep about by means of their suckers among the rocks, and lurk in holes. In Sepia the integument is produced laterally into two muscular fins, rather narrow and of uniform breadth running the whole length of the body, but separated by a notch behind. There are four pairs of short non-retractile arms surrounding the mouth, and furnished with suckers on their oral surface, and between the third and fourth of these arms on each side is a much longer tentacular arm, which is usually kept entirely withdrawn into a pocket of the skin. The mantle cavity is on the posterior side of the body, which is the lower side in the swimming position, and the funnel is a tube open at both ends and connected with the body within the mouth of the mantle cavity. The mantle during life performs regular respiratory movements by which water is drawn into the cavity, passing between mantle and funnel, and is expelled through the funnel. In swimming the short arms are directed forwards, the fins undulate, and the motion is slow and deliberate; but if the animal is threatened or alarmed it ' swims suddenly and rapidly backwards by expelling water forcibly from the mantle cavity through the funnel, at the same time expelling a cloud of ink from its ink-sac.

The Sepia feeds principally on Crustacea, and in aquaria has been observed to pursue and capture prawns. The method in

Fig. 1. Sepia officinalis, L., half the natural size, as seen when dead, the long prehensile arms being withdrawn from the pouches at the side of the head, in which they are carried during life when not actually in use. a, Neck; b, lateral fin of the mantle-sac; c, the eight shorter arms of the fore-foot ; d, the two long prehensile arms ; , the eyes.

which it secures its prey has been carefully observed and described by the present writer, who studied the living animal in the aquarium of the biological laboratory at Plymouth. The prawns support themselves on their long slender legs on convenient points of the rockwork, and the Sepia stalks them with great caution and determination, the rapid play of its chromatophores giving evidence of its excitement. When it has arrived within striking distance, the two tentacular arms are shot out with great rapidity, and the prawn is seized between the two expanded ends, drawn within the circle of short arms, and devoured; unless, as sometimes happens, the prawn springs away and the Sepia misses its aim.

Two species of Sepia occur in British and European waters, including the Mediterranean, namely, S. elegans and 5. officinalis. The usual length of the body is about 9 or 10 in. They live mostly between ten and forty fathoms, coming into shallower water in July and August to deposit their eggs, which are about as large as black currants and of somewhat similar colour, and are connected by elongated stalks into a cluster attached to the seabottom. Other species occur in various parts of the world, e.g. S. cultrata, which is common on the coasts of Australia. The Sepiidae form the only family of cuttle-fishes in which the shell is calcified. They belong to the tribe Myopsida, characterized by the complete closure of the external corneal covering of the eye outside the iris and the lens.

Sepiola and Rossia belong to another family of the Myopsida. Both are British genera living in shallow water, and entering estuaries. The animals of both genera are small, not more than 2 or 3 in. in length, with the body rounded at the aboral end, and the fins short and rounded, inserted in the middle of the body length, instead of extending from end to end. Sepiola, although it swims by means of its fins and funnel when active, spends much of its time buried in the sand for concealment. Rossia has similar habits. The shell is chitinous and shorter than the body. In other genera of the Sepiolidae the shell is entirely absent. Idiosepius is the smallest of the Cephalopoda, only 1-5 in. in length. It inhabits the Indian Ocean. The body is elongated and the fins rudimentary. In the Sepiadariidae also the shell is absent. The body is short and the mantle united with the head dorsally. The two genera Sepiadarium and Sepioloidea occur in the Pacific Ocean. The common squid Loligo is the type of the only remaining family of the Myopsida. In this species the shell is a well-developed chitinous pen or gladius with a thickened axis narrowing to a point behind, but bearing posteriorly a wide thin plate on each side. The shape closely resembles that of a quill pen with the quill in front. The fins are large and triangular, extending over rather more than half of the length of the body aborally. The tentacular arms are only partly retractile. The body is elongated and conical, and reaches about a foot in length. The squid is gregarious, and forms a favourite food of the larger fishes, especially of conger. All the Myopsida are more or less littoral in habit, and the British forms are familiar in consequence of their frequent capture in the nets of fishermen. The shell, or " bone " as it is commonly called, of the common Sepia frequently occurs in abundance on the shore among the sea-weed and other refuse left by the tide.

The Oigopsida, or cuttle-fishes in which the corneal covering of the eye is perforated, are on the whole more oceanic than littoral, and many of the species are abyssal. Ommatostrephes sagittatus is one of the forms that occurs off the British coasts,

Fig. 2. A, Loligo vulgaris; a, arms; t, tentacles. B, Pen of the same reduced in size. C, Side-view of one of the suckers, showing the horny hooks surrounding the margin. D, View of the head from in front, showing the arms (a), the tentacles (t), the mouth (m), and the funnel (/).

especially the more northern, e.g. in the Firth of Forth. In general appearance it resembles the common squid, but the fins are broader and shorter, not extending to the middle of the body.

The shell is similar to that of Loligo, but ends aborally in a little hollow cone. The suckers bear chitinous rings which are toothed along the outer edge. The tentacular arms are rather short and thick. Two specimens of allied species have been taken on British coasts, one of which, captured off, Salcombe in Devonshire in 1892, had a body 66 cm. (22 in.) long, and tentacular arms 64 cm. long, or nearly the same length as the body. Most of the species of Ommalostrephes are naturally gregarious and oceanic, and occur in the open seas in all latitudes, swimming near the surface and often leaping out of the water. They are . largely devoured by albatrosses and other marine birds, and by Cetacea. They are used as bait in the Newfoundland cod fishery.

Some of the oceanic cuttle-fishes reach a very large size, and the stories of these ocean monsters which are narrated by the older writers, though to some extent exaggerated, are now known to be founded on fact. The figure given by one author of a gigantic Cephalopod rising from the surface of the ocean and embracing with its arms a full-rigged ship does not accurately represent an actual occurrence, but on the other hand there are authentic instances on record of fishermen in small boats on the banks of Newfoundland being in great peril in consequence of large squids throwing their arms across their boats. In November 1874 a specimen was brought ashore at St John's, Newfoundland, which had been caught in herring nets. Its body was 7 ft. long, its fins 22 in. broad, and its tentacular arms 24 ft. long. Several others have been recorded, taken in the same region, which were as large or larger, the total length of the body and tentacles together varying from 30 to 52 ft., and the estimated weight of one of them being 1000 ft.

In April i87Soneof theselarge squids occurredoff Boffin'slsland on the Irish coast. The crew of a curragh rowed out to it and attacked it, cutting off two of its arms and its head. The shorter arms measured 8 ft. in length and 1 5 in . in circumference ; the tentacular arms are said to have been 30 ft. long. In the Natural History Museum in London there is one of the shorter arms of a specimen; this arm is 9 ft. in length and n in. in circumference, and the total length of the specimen, including body and tentacles, is stated to have been 40 ft. The maximum known length of these giant squids is stated to be 18 metres or about 585 ft. All these gigantic specimens belong, so far as at present known, to one genus called Architeuthis, referred to the same family as Ommalostrephes. They are the largest known invertebrates.

These huge cuttle-fishes as well as those of various other oceanic species form the food of the cachalot or sperm whale, and F. T. Bullen, in his Cruise of the Cachalot and other writings, has graphically described contests which came under his own observation between the cachalot and its prey. The prince of Monaco in his yacht the " Princess Alice " was fortunate enough to be able to make a very complete scientific investigation in the case of one specimen of the cachalot, which not only confirmed the most important of Mr Bullen's statements, but added considerably to our knowledge of oceanic cuttle-fishes. Off the Azores in July 1895 the prince in his yacht witnessed the killing of a cachalot 13-70 metres long (about 45 ft. 8 in.) by the crew of a whaler. The animal in its death-agony vomited the contentsof its stomach, most of which were carefully collected and preserved, and afterwards examined by Professor Joubin. On the lips of the whale were found impressions several centimetres wide which corresponded exactly to the toothed suckers of the largest cuttle-fish arms obtained from its stomach. The contents of the stomach consisted entirely of cuttle-fish or parts of cuttle-fish, including the giant Architeuthis, and among them was the body, without the head, of a form new to science, distinguished by a condition of the external surface which occurs in no other species of the group. The surface of the skin was divided into small angular flat projections like scales, arranged in a regular spiral like the scales of a pine cone. From this character the new genus was called Lepidoteuthis. The body, without the head, of the specimen obtained was 86 cm. (nearly 3 ft.) in length.

The family Onychoteuthidae is remarkable for the formidable chitinous hooks borne on the arms. These hooks are special modifications of % the toothed chitinous ring which covers the sucker-rim in the Decapoda generally. The teeth of the ring are often unequal in size, and in the Onychoteuthidae one tooth is enormously developed. The maximum development occurs in Veranya, found in the Mediterranean, where the suckers have lost their function and are merely fleshy projections bearing the hooks at their extremities. Onychoteuthis reaches a large size, the length of the body without the arms being in one specimen from the Pacific coast of America 8 ft. Figures of this and several of the following genera are given in the article CEPHALOPODA.

In the family Cheiroteuthidae many of the species occur at abyssal depths of the ocean, and exhibit curious modifications of structure. In Cheiroteuthis itself the tentacular arms are very long and slender, and are not capable of retraction into pockets. In several species of this genus the suckers are no longer organs of adhesion, but are simple cups containing a network of filaments resembling a fishing net. In Histioteuthis and Histiopsis, as in some Octopods, the six dorsal arms are more or less completely united by a web, which also probably serves for capturing fish. In these two genera and in Calliteuthis the skin bears luminous organs. Cheiroteuthis has been taken at 2600 fms., Calliteuthis at 2 200, Histiopsis at nearly 2000. Bathyteuthis, placed in the same family as Ommatoslrephes, has been taken at 1700 fms.

The Cranchiidae are remarkable for their small size, the shortness of the ordinary arms, and the protuberance of the eyes, which in Taonius are actually on the ends of stalk-like outgrowths of the body. Cranchia is a deep-sea form taken at 1700 fms. Its body is pear-shaped, swollen posteriorly and quite narrow at the neck.

Spirula is distinguished from all other existing Cephalopods by the structure of its coiled shell, which in many respects resembles those of the extinct Ammonites, and is not completely internal. In the structure of the body the animal is a true cuttlefish in the sense in which the term is here used, having ten arms and a perforated cornea. Three species are distinguished, and their empty shells occur abundantly on the shores of the tropical regions of the Atlantic, Pacific and Indian Oceans. In German the shells are known from their shape as Posthornchen. They are common on the shores of the Azores. But the animal has very rarely been obtained; only a few specimens occur in museum collections. One specimen was taken by the " Challenger " in a deep-sea trawl, at a depth between 300 and 400 fathoms off Banda Neira in the Molluccas. Dr Willemoes Suhm, in describing the capture, stated that the specimen seemed to have been in the stomach of a fish, as its surface was slightly digested, and he thought it must have habits of concealment which usually prevent its capture, and that it was secured on this occasion only by the capture of the fish which had swallowed it. The fact that the shells are washed ashore in such large numbers is not fully explained. Possibly when freed from the animal the air in the chambers of the shell causes it to float, and in that case it would naturally be sooner or later washed ashore. (J. T. C.)

Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)

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