Fig. 495.—Steindachnerella argentea (Goode & Bean). Gulf Stream.
The Murænolepidæ are deep-sea fishes, with minute eel-like scales, and no caudal fin. The ventrals are five-rayed and there are 10 pterygials.
CHAPTER XXXI
ORDER PEDICULATI: THE ANGLERS
The Angler-fishes.—The few remaining fishes possess also jugular ventral fins, but in other regards they show so many peculiarities of structure that we may well consider them as forming a distinct order, Pediculati (pedicula, a foot-stalk), although the relation of these forms to the Batrachoididæ seems a very close one.
The most salient character of the group is the reduction and backward insertion of the gill-opening, which is behind the pectoral fins, not in front of them as in all other fishes. The hypocoracoid and hypercoracoid are much elongate and greatly changed in form, so that the pectoral fin is borne on the end of a sort of arm. The large ventrals are similarly more or less exserted. The spinous dorsal is much reduced, the first spine being modified to form a so-called fishing-rod, projecting over the mouth with a fleshy pad, lure, or bait at its tip. The form of the body varies much in the different families. The scales are lost or changed to prickles and the whole aspect is very singular, and in many cases distinctly frog-like. The species are mostly tropical, some living in tide-pools and about coral reefs, some on sandy shores, others in the oceanic abysses.
The nearest allies of the Pediculates among normal fishes are probably the Batrachoididæ. One species of Lophiidæ is recorded among the fossils, Lophius brachysomus, from the Eocene of Monte Bolca. No fossil Antennariidæ are known. Fossil teeth from the Cretaceous of Patagonia are doubtfully named "Lophius patagonicus."
The Fishing-frogs: Lophiidæ.—In the most generalized family, that of the fishing-frogs (Lophiidæ), the body is very much depressed, the head the largest part of it. The mouth is excessively wide, with strong jaw-muscles, and strong sharp teeth. The skin is smooth, with dermal flaps about the head. Over the mouth, like a fishing-rod, hangs the first dorsal spine with a lure at the tip. The fishes lie flat on the bottom with sluggish movements except for the convulsive snap of the jaws. It has been denied that the bait serves to attract small fishes to their destruction, but the current belief that it does so is certainly plausible. As to this Dr. Gill observes:
"The name 'angler' is derived from the supposition that by means of the foremost dorsal spine, which bears leaf-like tags, or appendages, at the end, it angles for fishes itself, lying upon the ground with its head somewhat upraised. According to Mr. S. Kent, however, this is at most only partly the case: 'That the fish deliberately uses this structure as a fisherman does his rod and line for the alluring and capture of other fish is a matter of tradition handed down to us from the time of Pliny and Aristotle, and which scarcely any authority since their time has ventured to gainsay. Nevertheless, like many of the delightful natural-history romances bequeathed to us by the ancient philosophers, this one of the angler-fish will have to be relegated to the limbo of disproved fiction. The plain and certain ground of facts, all the same, has frequently more startling revelations in store for us than the most fervid imaginations of philosophers, and that this assertion holds good in the case now under consideration must undoubtedly be admitted. It is here proposed to show, in fact, that the angler is one of the most interesting examples upon which Nature has exercised her handicraft, in the direction of concealing the identity of her protégé, such ingenuity being sometimes utilized with the object of protecting the organism from the attacks of other animals, or, as illustrated in the present instance, for the purpose of enabling it by stealth to obtain prey which it lacks the agility to hunt down after the manner of ordinary carnivorous fishes. To recognize the several details here described, it will not suffice to refer to examples simply, and usually most atrociously stuffed, nor even to those preserved in spirit, in which all the life colors are more or less completely obliterated and the various membranous appendages shrunk up and distorted. In place of this, a healthy, living example fresh from the sea, or, better still, acclimatized in the tanks of an aquarium, must be attentively examined, and whereupon it will be found that this singular fish, throughout the whole extent of its superficies, may be appropriately designated a living sham."