The third order, Selachia, includes a number of cartilaginous fish, varying much in form; the rays, dog-fish, skate, torpedo, shark, and saw-fish belong to this important division. The torpedo has the power of giving a strong electrical shock. Redi, an Italian naturalist of the seventeenth century, first studied them carefully. He caught and landed an electric ray, and pressing it with his hand, experienced a tingling sensation, which extended to his arms and shoulders, and was followed by a disagreeable trembling. This electric power dies with the animal. Dr. Walsh made some interesting experiments with them. He placed [pg 160]a living torpedo on a clean wet towel, and connected brass wires with it. Round the torpedo were eight persons, standing on isolating substances. One end of the wire was placed in a basin full of water. The first person had a finger of one hand in this basin, and a finger of the other in a second basin, also full of water. The second person had a finger in the last-named basin, and a finger of the other hand in a third basin, and so on round the circle of eight persons. The end of the second wire was plunged into the last basin of the series, thus establishing a complete electric circuit. At the moment when the experimenter touched the torpedo a tolerably strong shock was felt by all participating. When the torpedo was placed on an isolated supporter, it showed its energy by communicating to several persons forty or fifty shocks in the short space of a minute and a half.
The family Carcharidæ includes the true sharks, some species of which attain to a length of twenty, or even thirty, feet. They are the terror of all other fish and molluscs. “But the prey which has the greatest charm for him is man; the shark loves him dearly, but it is with the affection of the gourmand. If we may believe some travellers, when several varieties of human food comes in its way, the shark prefers the European to the Asiatic, and both to the negro.” He has been known to jump clean aboard a fisherman’s boat, and even to snap up a sailor from the shrouds. Commerson relates the following:—The corpse of a negro had been suspended from a yard-arm twenty feet above the level of the sea. A shark was seen making every effort to reach the body, which eventually he did, and tore it limb from limb in presence of the horror-stricken crew. The mouth of the shark is placed in the lower part of the head, and the animal has to turn itself in the water before he can seize an object above him. On the African coast the negroes take advantage of this fact; they swim towards him, and seize the moment when he turns to rip up his belly with a large strong knife. The adult shark has six rows of murderous-looking teeth, forming a perfect arsenal of deadly weapons.
Captain Basil Hall describes the mode by which sharks are sometimes captured. “The sharp-curved dorsal fin of a huge shark was seen rising about six inches above the water, and cutting the glazed surface of the sea by as fine a line as if a sickle had been drawn along it. ‘Messenger, run to the cook for a piece of pork,’ cried the captain, taking the command with as much glee as if an enemy’s cruiser had been in sight. ‘Where’s your hook, quartermaster?’ ‘Here, sir, here,’ cried the fellow, feeling the point, and declaring it was as sharp as any lady’s needle, and in the next instant piercing with it a huge junk of pork weighing four or five pounds. The hook, which is as large as one’s little finger, has a curvature about as large as a man’s hand when half closed, and is six or eight inches in length, while a formidable line, furnished with three or four feet of chain attached to the end of the mizen topsail halyard, is now cast into the ship’s wake.
“Sometimes the very instant the bait is cast over the stern the shark flies at it with such eagerness that he actually springs partially out of the water. This, however, is rare. On these occasions he gorges the bait, the hook, and a foot or two of the chain, without any mastication, and darts off with the treacherous prize with such prodigious velocity that it makes the rope crack again as soon as the coil is drawn out. Much dexterity is required in the hand which holds the line at this moment. A bungler is apt [pg 161]to be too precipitate, and jerk away the hook before it has got far enough into the shark’s stomach. The secret of the sport is to let the monster gulp down the whole bait, and then to give the line a violent pull, by which the barbed point buries itself in the coat of the stomach. When the hook is first fixed it spins out like the log-line of a ship going twelve knots.
“The suddenness of the jerk with which the shark is brought up often turns him quite over. No sailor, however, thinks of hauling one on board merely by the rope fastened to the hook. To prevent the line breaking, the hook snapping, or the jaw being torn away, a running bowline is adopted. This noose is slipped down the rope and passed over the monster’s head, and is made to join at the point of junction of the tail with the body; and now the first part of the fun is held to be completed. The vanquished enemy is easily drawn up over the taffrail, and flung on deck, to the delight of the crew.” Even then he is sometimes a very formidable enemy. The flesh of the shark, though sometimes eaten, is coarse and leathery.
THE COMMON SHARK (Carcharias vulgaris).
On several of the smaller islands of the Spanish Main whaling stations are established. After the huge fish have been captured, they are towed by the boats to one of these stations, and the blubber is stripped off and carried on shore to the boiling-house in large white blocks, where a simple apparatus is set up for “trying-out” the oil. It sometimes happens that immediately after the whale has been killed the sharks surround it in such numbers, and devour the blubber with such rapacity, that if the distance be great and the currents adverse, the greater part has been eaten off before the whale can be towed ashore; and the labour of the fishermen is thus thrown away.
The tiger-shark is a more formidable monster than others of its tribe, because of its power of seizing its prey without turning on its back or side. It is enabled to do this from the great size of its mouth, and from its position, which is near the end of the snout, instead of underneath, as in other varieties of the shark.
“As soon as the carcase of the whale has been stripped of its blubber, it is towed out at high water to a sufficient distance from the station to ensure of its being carried away by the falling tide. This is necessary, for the stench from so large a mass of putrefying flesh, exposed as it has been to the intense action of a tropical sun for three or four days, is more than unpleasant.