The Octopus, Squid And Cuttle have no outer shells, and protect themselves from their enemies by expelling from a little bag an inky fluid which discolours the water and hides them. Most of the head-footed ones —and the octopus in particular—have the power of changing colour at will, making themselves almost invisible when clinging to rocks.
Of the octopus (poulpe or devil fish), there are many species. As the name indicates, it has eight feet, arms, or feelers, which are united near the body by a web, just as the toes of a duck are joined together. On each feeler are two rows of suckers, a hundred and twenty of them to each arm, so that the fish not only has the power of seizing its unfortunate prey by enclosing it in its hideous arms, but, by merely touching it and bringing its suckers to bear, can hold it fast. It is a night feeder, hiding during the day. Mr. S. Hanley, the conchologist, when wintering in Italy, observed some octopods in Leghorn Harbour, the tentacles of which were about four feet in length. They were greatly feared by the divers and bathers of the place. In 1879 a Government diver named Small was caught by an octopus at the bottom of the sea, in the tidal portions of the river Mogne, Melbourne. Fortunately, he had one arm free, and drawing an iron bar towards him with his foot, he successfully fought the monster—which measured nearly eight feet across—and was pulled up to the surface in a state of great exhaustion and terror at the end of about twenty minutes.
With their powerful beaks these creatures can break the shells of crabs and lobsters, but are themselves fed on by many kinds of sea fish, particularly congers. Quite a horrible tragedy once took place in Havre Aquarium. It was graphically described by Mr. Henry Lee, F.L.S., in his work on ' The Octopus, or the Devil Fish of Fiction and Fact.' The curator of the aquarium threw the octopus into a tank of congers. It at once perceived its danger, and endeavoured to conceal its presence by stretching itself along a rock the colour of which it immediately assumed. Apparently seeing it was discovered, it changed its tactics, and shot backward in quick retreat, leaving behind it a long black trail of turbid water, formed by the discharge of its ink. Then it fixed itself to a rock with all its arms surrounding and protecting its body, presenting on all exposed sides a surface furnished with suckers, and awaited the attack of its enemy. A conger approached, and, having found a vulnerable place, seized a mouthful of the living flesh. Then, straightening itself up in the water, it turned round and round with giddy rapidity until the arm was with a violent wrench torn away from the body of the victim. Each bite of the conger cost the octopus a limb ; finally nothing remained but a dismembered body, which was devoured by some dogfishes.
In aquariums octopods have been seen to build themselves little grottos of oysters, where they dwell in peace and happiness during the daytime, wandering at night, sometimes leaving their tanks and travelling into others on voyages of discovery, adventure, and depredation. In some parts of the world they are attracted by white shells or stones spread on the bottom of the sea, and rows of jars which act as traps are laid in which they hide and are captured.
The chameleon-like habit of changing colour when irritated is one of the most remarkable features of several members of the cephalopoda. I once happened upon a very fine specimen of octopus in a rocky pool on the Welsh coast, where it had been left by the receding tide. It was a bright red colour, and, on my touching it with my crab hook, purple spots began to show on the red. Interfering with it still further, the red ground gradually died away, and it became a piebald yellow and purple creature. Then I thought I would put it in a prawn net and take it home, whereupon it straightway turned the most ghastly livid colour imaginable, assuming the pallor of death. I had hopes of keeping this strange thing alive, and presented it with a tenement in the shape of a bucket of salt water; but it received so many pokes and touches from various people to bring out those chameleon-like changes, that during the night it gave up the ghost.
Of much greater importance from an angler's point of view is the common squid or calamary (Loligo vulgaris). It is sometimes called the pen-and-ink fish, on account of its ink bag, and the delicate elongated shell which is found within it. The octopus has a similar shell, these two being in this respect very different from the cuttle, which possesses inside it the stout shield-shaped, calcareous mass so often found on the seashore. In aged squid are sometimes found more than one shell. These fish, of which there are about nineteen species altogether, abound off Cornwall. One of the most remarkable is the Sagittated Calamary which the sailors call the flying squid, or sea arrow. By filling itself with water and rapidly expelling it, the flying squid projects itself with great force above the surface of the sea, sometimes falling on the decks of ships. It is the Ommastrephes sagittatus that is so largely used as a bait for cod by the Newfoundland fishermen, who catch these curious creatures in great numbers by means of a jigger—a cone-shaped piece of lead from which about half a dozen hooks project. The squid catchers go out in small craft about sundown, each boat often coming in with a hundred or more of these valuable baits.
Calamaries of enormous size are caught from time to time in foreign seas, and there is a record of one monster seen in British waters. It was given in the ' Zoologist' for June 1875. A dark mass was observed in the sea by the crew of a curragh or large coracle, north-west of Boffin Island, Connemara. At first they thought it was a wreck, and rowed up to it, when they discovered it to be a huge calamary. Certainly with much daring, they cut off one of its arms. The thing, which was probably dying or injured, fled, but they followed it, and succeeded in cutting off another arm and also the head. One accepts these stories of marine marvels with reservation, but in this case the pieces, labelled Architeuthis dux, are in the Dublin Museum. The shorter arms were about eight feet in length. A creature of this size would have no difficulty in destroying a man, and I have suggested that it may have been dead when seen by the fishermen. That gulls were hovering over it points to this.