National Geographic : 1921 Jan
INTERESTING CITIZENS OF THE GULF STREAM By DR. JOHN T. NICHOLS, CURATOR OF RECENT FISHES W E THINK of tropical seas as the home of a gaudily colored assemblage of fishes. In a sense, this first impression is correct. Active, short-bodied, elastic-scaled, spiny finned, bright-colored species here occupy the center of the stage. As a matter of fact, tropical shore lines are the great metropolis of the world's fish life. The evil-visaged snake like Moray (Plate III). one of the most degenerate of true fishes, threads the hidden passages among the coral over which Blue Angel (Plate II) and red, green, or parti-colored Parrot-fish (Plate VIII) are swimming. Out on the open sand, spotted floun ders lie. matching their background so as to be well nigh invisible, or little gray gobies move about like shadows, eager to escape detection. Countless varieties of fishes are hiding in every patch of weed. Schools of sil versides, anchovies, and herring dart through the stretches of open water. It is their function, in the scheme of things, to feed on the minute organisms so abundant in sea water, to multiply prodigiously, and in turn form a basic food supply for a great variety of larger fishes. To do this and at the same time con tribute something to the forces of evolu tion, their numbers must be conserved, however. Their silvery sides render them difficult of observation, by hungry eyes below, and they are available only to the quick and the keen. ENORMOUS QUANTITY AND DIVERSITY OF LIFE IN THE GULF STREAM Over the heat equator warm air is con stantly rising. Heavier cooler air from higher latitudes flows steadily in to take its place, and, deflected by the earth's ro tation, becomes the easterly trade winds, before which millions of waves, reflecting the clear deep blue of the ocean depths under their white crests, go dancing to the westward. The whole surface of the tropical At lantic moves, drifting toward the coast of America, is caught and turned about in the Gulf of Mexico, and shoots out past the Keys and the east coast of Flor ida as the Gulf Stream. Inasmuch as many young marine fishes and other animals regularly drift in ocean currents, it is easy to understand what an enormous quantity and diversity of life the Gulf Stream must carry. Furthermore, such waters, when they enter the Gulf, have already flowed under a tropical sun for many, many miles. The Gulf of Mexico is not a place for them to lose calories, and Gulf Stream water has a considerably higher temper ature than the 79 degrees found, in gen eral, at the surface of the open ocean on the Equator. TRULY TROPICAL FISHES IN FLORIDA WATERS It follows that shores bathed by such water have as truly tropical fishes as if they were situated much farther south. Essentially the same fishes extend from Florida to Brazil. Scattered representa tives of this great tropical fish fauna of the western Atlantic are drifted to the capes of the Carolinas and, to a less ex tent. in summer, even to New England. We have seen a stray Spade Fish (Chcc todipterus faber) (Plate II) on the New Jersey coast and a little Butterfly Fish (Chctodon ocellatus) (Plate III) washed ashore on the south side of Long Island, New York. It is a little over ten years ago that the writer made a first trip to Florida. After a prolonged period of more or less dis tasteful. though necessary, indoor activ ities during) a northern winter, he found himself suddenly foot-loose on the Miami water-front. The yachting party that he was to join here on a collecting trip among the Keys was somewhere up the coast, stuck on a sand-bank. Meanwhile, there was noth ing to do but sit and swing one's heels.