It was, in the first place, observed by Mr. Kent "that the fish while quietly reclining upon the bottom of its tank presented a most astonishing resemblance to a piece of inert rock, the rugose prominences in the neighborhood of the head lending additional strength to this likeness. This resemblance being recognized, it was next found, on a little closer inspection, that the fish constituted, in connection with its color, ornamentations, and manifold organs and appendages, the most perfect facsimile of a submerged rock, with that natural clothing of sedentary animal and vegetable growths common to boulders lying beneath the water in what is known as the laminarian zone. In this manner the numerous simple or lobulated membranous structures dependent from the lower jaw and developed as a fringe along the lateral line of the body imitate with great fidelity the little flat calcareous sponges (Grantia), small compound ascidians, and other low organized zoophytic growths that hang in profusion from favorably situated submarine stones. That famous structure known as the angler's 'rod and bait' finds its precise counterpart in the early growing phase of certain sea-plants, such as the oarweed (Laminaria), while the more posterior dorsal fin-rays, having short lateral branchlets, counterfeit in a like manner the plant-like hydroid zoophytes known as Sertulariæ. One of the most extraordinary mimetic adaptations was, however, found in connection with the eyes, structures which, however perfectly the surrounding details may be concealed, serve, as a rule, to betray the animal's presence to a close observer. In the case of the angler, the eyes during life are raised on conical elevations the sides of which are separated by darker longitudinal stripes into symmetrical regions, the structure, as a whole, with its truncated summit upon which the pupil opens, reproducing with the most wonderful minuteness the multivalve shell of a rook barnacle (Balanus). To complete the simile the entire exposed surface of the body of the fish is mapped out by darker punctated lines into irregular polygonal areas, whose pattern is at once recognized by the student of marine zoology as corresponding with that of the flat, cushion-like expansions of the compound tunicate Botryllus violaceus. Thus disguised at every point, the angler has merely to lie prone, as is its wont, among the stones and débris at the bottom of the sea and to wait for the advent of its unsuspecting prey, which, approaching to browse from what it takes to be a flat rock—differing in no respect from that off which it obtained the last appetizing morsel of weed or worm—finds itself suddenly engulfed beyond recall within the merciless jaws of this marine impostor."
Fig. 496.—Anko or Fishing-frog, Lophius litulon (Jordan). Matsushima Bay, Japan.
The great fishing-frog of the North Atlantic, Lophius piscatorius, is also known as angler, monkfish, goosefish, allmouth, wide-gape, kettleman, and bellows-fish. It is common in shallow water both in America and Europe, ranging southward to Cape Hatteras and to the Mediterranean. It reaches a length of three feet or more. A fisherman told Mr. Goode that "he once saw a struggle in the water, and found that a goosefish had swallowed the head and neck of a large loon, which had pulled it to the surface and was trying to escape. There is authentic record of seven wild ducks having been taken from the stomach of one of them. Slyly approaching from below, they seize birds as they float upon the surface."
"The angler, or goosefish, spawns in summer along the eastern Atlantic coast, and the result of its labor is quite remarkable. 'The eggs are very numerous, inclosed in a ribbon-shaped gelatinous mass, about a foot in width and thirty or forty feet long, which floats near the surface. One of these ribbons will weigh perhaps forty pounds, and is usually partially folded together and visible a foot or eighteen inches from the top of the water, its color being brownish purple. The number of eggs in one of these has been estimated to be from forty to fifty thousand.' The growth of the young after exclusion from the egg is rather rapid, and Professor Goode saw 'young fish two or three inches long' while others were yet spawning, and these young fish were presumably the fry of those that had spawned the same year, only somewhat earlier. In a few days after hatching they present a striking appearance on account of the enormous development of the pectoral and ventral fins."
Aristotle gives, according to Professor Horace A. Hoffman, this account of the angler: "'Inasmuch as the flat, front part is not fleshy, nature has compensated for this by adding to the rear and the tail as much fleshy substance as has been subtracted from the front.' The βάτραχος is called the angler. He fishes with the hair-like filaments hung before his eyes. On the end of each filament is a little knob, just as if it had been placed there for a bait. He makes a disturbance in sandy or muddy places, hides himself and raises these filaments. When the little fish strikes at them he leads them down with the filaments until he brings them to his mouth. The βάτραχος is one of the σελάχη. All the σελάχη are viviparous or ovoviviparous except the βάτραχος. The other flat σελάχη have their gills uncovered and underneath them, but the βάτραχος has its gills on the side and covered with skinny opercula, not with horny opercula like the fish which are not σελαχώδη. Some fishes have the gall-bladder upon the liver, others have it upon the intestine, more or less remote from the liver and attached to it by a duct. Such are βάτραχος, ἔλλοψ, συνάγρίς, σμύραινα, and ξιφίας. The βάτραχος is the only one of the σελάχη which is oviparous. This is on account of the nature of its body, for it has a head many times as large as the rest of its body, and spiny and very rough. For this same reason it does not afterwards admit its young into itself. The size and roughness of the head prevent them both from coming out (i.e., being born alive) and from going in (being taken into the mouth of the parent). The βάτραχος is the most prolific of the σελάχη, but it is scarce because the eggs are easily destroyed, for it lays them in a bunch near the shore."
The genus Lophius of northern range has a vertebral column of about thirty vertebræ. Lophius litulon occurs in Japan. In the North Pacific is found Lophiomus, similar in appearance but smaller in size, ranging southward to the equator, a southern fish having but eighteen vertebræ. Lophiomus setigerus is the common anko of Japan, and other species are recorded from Hawaii, and the Galapagos.
The Sea-devils: Ceratiidæ.—The sea-devils, or Ceratiidæ, are degenerate anglers of various forms, found in the depths of the arctic seas. The body is compressed, the mouth vertical; the substance is very soft, and the color uniform black. Dr. Günther thus speaks of them:
Fig. 497.—Cryptopsaras couesi Gill. Gulf Stream.