Only two species of this genus are known: the one of the Mediterranean, Stomia boa (Fig. 381), the other of the Atlantic Ocean, S. barbatus, so called from the long barbula on the chin. Both species are black in colour, with numerous small silvery spots on the abdomen. The body of S. boa is thin, compressed, covered with little thin scales of blackish blue, much spotted on the back and abdomen, a little brighter on the sides—the head, in some respects, recalling that of a serpent.
Flying is so much associated in our minds with the usual denizens of the air, that the idea of flying-fishes seems to be a contradiction. Nevertheless, some fishes possess that power, the fins being transformed into wings, which they are enabled to raise for a few seconds. These wings, however, are neither long nor powerful, for they rather act the part of a parachute than wings. The distinguishing characteristic of the Exocœtus, or flying-fish, is the pectoral fins, nearly the length of the body, the head flattened above and on the sides, the lower part of the body furnished with a longitudinal series of carinated scales on each side, the dorsal fin placed above the anal, the eyes large, and the jaws furnished with small pointed teeth.
Fig. 381. Stomia boa.
The Flying-fishes (Fig. 382) in their own element are harassed by attacks of other inhabitants of the ocean, and when under the excitement of fear they take to the air, they are equally exposed to the attacks of aquatic birds, especially the various species of gulls. We have said that, in their leap from the water, their fins sustain them rather as parachutes than wings, with which they beat the air. Mr. Bennett's description is pretty clear on this point. "I have never," he says, "been able to see any percussion of the pectoral fins during flight; and the greatest length of time I have seen this volatile fish on the fly has been thirty seconds by the watch, and the longest flight, mentioned by Captain Basil Hall, has been two hundred yards, but he thinks that subsequent observation has extended the space. The usual height of their flight, as seen above the surface of the water, is from two to three feet, but I have known them come on board at the height of fourteen feet and upwards. And they have been well ascertained to come into the chains of a line of battle ship, which is considered to be upwards of twenty feet. But it must not be supposed that they have the power of raising themselves into the air after having left their native element; for on watching them I have often seen them fall much below the elevation at which they first rose from the water; nor have I ever in any instance seen them rise from the height to which they first sprang, for I conceive the elevation they take depends on the power of the first spring."
Fig. 382. The Flying-fish (E. exiliens).
The most common species is E. volitans. Its brilliant colouring would seem designed to point it out to its enemies, against whom it is totally defenceless. A dazzling silvery splendour pervades its surface. The summit of its head, its back, and its sides, are of azure blue; this blue becomes spotted upon the dorsal fin, the pectoral fin, and the tail. This fish is the common prey of the more voracious fishes, such as the shark, and the sea-birds; its enemies abound in the air and water. If it succeeds in escaping the Charybdis of the water, the chances are in favour of its coming to grief in the Scylla of the atmosphere—if it escapes the jaws of the shark, it will probably fall to the share of the sea-gull. The dolphin is also a formidable enemy to the much-persecuted flying-fish. Captain Basil Hall gives a very animated description of their mode of attack.[17] He was in a prize, a low Spanish schooner, rising not above two feet and a half out of the water. "Two or three dolphins had ranged past the ship in all their beauty. The ship in her progress through the water had put up a shoal of these little things (flying-fish), which took their flight to windward. A large dolphin which had been keeping company with us abreast of the weather gangway at the depth of two or three fathoms, and as usual glistening most beautifully in the sun, no sooner detected our poor dear friends take wing than he turned his head towards them, darted to the surface, and leaped from the water with a velocity little short, as it seemed to us, of a cannon-ball. But though the impetus with which he shot himself into the air gave him an initial velocity greatly exceeding that of the flying-fish, the start which his fated prey had got enabled them to keep ahead of him for a considerable time. The length of the dolphin's first spring could not be less than ten yards, and after he fell we could see him gliding like lightning through the water for a moment, when he again rose, and shot upwards with considerably greater velocity than at first, and of course to a still greater distance. In this manner the merciless pursuer seemed to stride along the sea with fearful rapidity, while his brilliant coat sparkled and flashed in the sun quite splendidly. As he fell headlong in the water at the end of each leap, a series of circles were sent far over the surface, for the breeze, just enough to keep the royals and topgallant studding-sails extended, was hardly felt as yet below.
"The group of wretched flying-fishes, thus hotly pursued, at length dropped into the sea; but we were rejoiced to observe that they merely touched the top of the swell, and instantly set off again in a fresh and even more vigorous flight. It was particularly interesting to observe that the direction they took now was quite different from the one in which they had set out, implying but too obviously that they had detected their fierce enemy, who was following them with giant steps along the waves, and was gaining rapidly upon them. His pace, indeed, was two or three times as swift as theirs, poor little things! and the greedy dolphin was fully as quick-sighted; for whenever they varied their flight in the smallest degree, he lost not the tenth part of a second in shaping his course so as to cut off the chase; while they, in a manner really not unlike that of the hare, doubled more than once upon the pursuer. But it was soon plainly to be seen that the strength and confidence of the flying-fish were fast ebbing; their flights became shorter and shorter, and their course more fluttering and uncertain, while the leaps of the dolphin seemed to grow more vigorous at each bound. Eventually this skilful sea-sportsman seemed to arrange his springs so as to fall just under the very spot on which the exhausted flying-fish were about to drop. This catastrophe took place at too great a distance for us to see from the deck what happened; but on our mounting high on the rigging, we may be said to have been in at the death; for then we could discover that the unfortunate little creatures, one after another, either popped right into the dolphin's jaws as they lighted on the water, or were snapped up instantly after."
THE CLUPEADÆ.