National Geographic : 1937 Feb
DENIZENS OF OUR WARM ATLANTIC WATERS BY ROY WALDO MINER* VOYAGING southward from New York toward tropic waters on a midwinter day, we gaze out over a leaden sea of dull-green color, lashed by the stiff, chilling wind. But the next morn ing we awaken to a balmy air and go on deck to behold the ocean miraculously changed to ultramarine blue, the dark, swelling waves crowned with snowy foam which churns up in the wake of the vessel in turquoise turmoil before reaching the surface. Petrels follow the ship, skipping from wave to wave. Toward afternoon a school of porpoises glides in and out of the sea in never-ending chase, while flying fishes, glinting in blue and silver, dart anxiously from the water and sail long distances, flicking the wave crests with their tails to gain momentum. We are in the Gulf Stream, that mar velous river in the ocean, which gives the North Atlantic its unique character and profoundly affects its temperature even as far as the North Sea, bestowing upon the British Isles and Scandinavia the inesti mable boon of a chastened climate.t We can imagine the surprise of Ponce de Leon when, sailing along the coast of Flor ida in 1513, he found his ship borne irre sistibly northward in its current. We acknowledge the service rendered to sea men by Benjamin Franklin, who advised vessels bound for England to take advan tage of its northeastward course. THE GULF STREAM'S MAGIC TOUCH The Gulf Stream exerts an influence on the spread and distribution of the marine life of the Atlantic which cannot be over estimated. The main current warms the whole North Atlantic, and spurs setting in toward the coast have a striking effect on the dis tribution of floating life off the Middle * This is the second of two articles by Dr. Miner, Curator of Marine Life, American Museum of Natural History, describing coastal creatures of the eastern seaboard. The first, "Sea Creatures of Our Atlantic Shores," with paintings by Else Bostelmann, appeared in THE NATIONAL GEO GRAPHIC MAGAZINE for August, 1936. t See "The Grandest and Most Mighty Terres trial Phenomenon: The Gulf Stream," by Rear Admiral John Elliott Pillsbury, NATIONAL GEO GRAPHIC MAGAZINE, August, 1912. Atlantic States and southern New England. Here, however, the warm stream is sepa rated from shore by colder waters forming what is known as the "Cold Wall." South of the Grand Banks of Newfoundland it meets the icy Labrador Current which flows down from the north, bringing a northern fauna and making its influence felt along the shore, particularly north of Cape Cod. The Gulf Stream, on the other hand, ex tends the range of many West Indian and other tropical species far to the northward during the summer, some of them being borne to the British Isles, so that the pelagic life of the mid-Atlantic is more tropical in character than that of the same latitude on the North American coast. LIVING FLEETS SAIL SUNNY WATERS Let us sail out across the Gulf Stream in a southeasterly direction, keeping our eyes open for evidences of its floating life. It is a calm day. Our seagoing launch glides over quiet waters, but the northeast ward drift of the current is obvious. Suddenly we see a graceful, translucent object, like an oddly elongated bladder, floating on the surface. It is brilliantly colored blue and crimson, the hues more intense at its tapering ends and shading into a play of delicate transparent tints along its sides. As we come nearer we see still others, and soon we realize that we are steering into the midst of a fleet of these fairy craft. Each one erects a crest resembling a succes sion of iridescent, foamlike bubbles along its summit, bordered with an edging of deep crimson. These are the Portuguese man-of-war (Physalia pelagica), an organism related to the hydroids and jellyfish, but consisting of a whole colony of connected individuals floating as a unit (Plate II). At first glance only one member of the colony is visible. But, as we look down ward through the transparent water, we see masses of smaller tube-shaped projections depending from its lower side just beneath the surface. The majority are deep blue, while scattered here and there among them are clusters of salmon pink, and fingerlike protuberances of green. Fringelike strings edged with bluish beads float out from this mass, jerking spasmodically.