Fish That Fish For Fish

There are fish that fish for fish with worms. That is, they use wormlike appendages of their own bodies, developed through millenia of evolution, to catch worm-eating fellow fishes. This curious quirk of fishing fish is revealed in a bulletin of the International Oceanographic Foundation.

The practice is confined to the pediculati, known as angler fishes. The best known of them lies on the bottom partially concealed in sand or mud. One of the spines of its dorsal fin is extended in the form of a jointed fishing rod. At the end there is a fleshy lump, with a striking resemblance to one of the most tasty marine worms. The fish lies perfectly still with its enormous mouth closed, while the wormlike end of its rod waves to and fro. Other fishes approach the lure until they come within striking range. Then the great mouth opens with remarkable speed and engulfs the prey, which is prevented from escaping by backward-directed teeth.

Some other deep-sea anglers have luminous lures at the tip of the rod, somewhat like a small, light-emitting fish. In the total darkness of deep waters this is fatally attractive. Because of the huge size of the angler’s mouth the prey may be almost as large as the fisherman. Other deep-sea fishes dispense with the rod but have light-emitting organs on the sides of the body. These must play some part in attracting other sea animals. Some of these luminous fishes are able to swallow other fishes many times their own size because of their ability to distend their mouths and throats.

About all the ways man has devised for catching fish have been devised by fishes themselves long before man came on the scene. Traps—for example. There is a fish in Florida waters known as the greater sand eel. It lies buried in the sand, with its great mouth open. A relative, the lesser sand eel, when frightened dives into what seems like an opening in the sand. The result is that the greater sand eel is nearly always found with a lesser sand eel, head down, in its stomach.

The ways of fish are being studied with the possibility of finding something human fishermen have not yet thought about. Thus far nothing strikingly new has developed. There recently has been much interest, says the report, in “electric fishing—either stunning fish or directing them into nets by means of electric currents.” But, it is pointed out, “the fishes themselves have long ago adopted this for their own use.” The electric ray on each side of its flat, round body has an area in which numerous cells are modified to produce electricity. This is not really so amazing when we consider that electrical impulses are generated normally in small amounts by both nerve and muscle cells. In these particular fishes, however, the electrical impulses are considerable and the arrangement of cells, like those of a battery, builds up a total electric potential sufficient to stun or even kill smaller animals in the surrounding water.

In only one case has man been able to use fish to catch fish. This has been by means of the remora, or sucking fish, which has the habit of attaching itself by means of suckers to other fishes. In 1494 Columbus witnessed the use of a captive remora for capturing turtles. It still is used for this purpose in parts of Australia and China.

The sucker fish has quite strong powers of adhesion. In the ordinary course of its life it attaches itself to sharks or other large fishes and enjoys a free ride until it comes across food. When used for fishing, it is fastened with a line around its tail and tethered to the canoe. The native paddles as close as possible to the intended victim without disturbing it. The remora then is thrown into the water toward the turtle, to which it automatically attaches itself. Once the remora is securely fixed to the turtle, the fisherman carefully plays his light line until the reptile is brought into the boat. This must be done with care because of the diving habits of turtles. They are likely to run away with lines, sucker fishes and all.