National Geographic : 1952 Jul
56 Marine Laboratory, University of Miami Magnification, Making a Dime Bigger than a Dollar, Lays Bare the Teeming Sea Planktonic organisms dwell in lakes and rivers as readily as in oceans. They reproduce with unbelievable fecundity; acorn barnacles may raise 20 tons of young a year for each mile of shore (below and page 48). This sample consists largely of seedlike copepods (pages 45 and 47). Transparent ribbons are arrowworms; two elongated triangles are pteropods. A salp's diaphanous form (right) suggests the ectoplasm of a ghost. until they were old enough to take care of themselves. The answer to this is to produce so many babies that there are plenty to spare. This process has been carried so far that the average egg production from each female creature in the plankton is probably about a million a year. Since most of these will be eaten before they ever grow up, this adds up to a tremendous food supply for such fishes as herring and mackerel. The little acorn barnacles that grow on our rocky coasts may produce as many as 20 tons of babies a year for each mile of shore, and the barnacle is but one of the many animals that live there. Of course, it must be borne in mind that the plankton is not composed solely of babies or even of animal life. Plant life and tiny but adult animals compose a large percentage. The farther we go from shore, and the deeper below the surface, the less we know about plankton. It is only natural that the more accessible places should have been ex- plored first. Yet there is much that we urgently need to know about the life of the open ocean. We know that fresh-water eels go to deep midocean waters to breed. We know too the story of the thousands of miles that the baby eels have to travel to return to the rivers. But what about gamefish like marlin, wahoo, and others? They probably live their early life in the ocean plankton, but we do not know where or how. These ocean waters come very close inshore along Florida's east coast; half an hour's sailing from Miami and you are in them. One laboratory in one year, or even in a life time, can begin to touch only the fringe of the problems that lie waiting in these waters. Yet we hope to continue learning more and more about the private life of the plankton.* * See "Living Jewels of the Sea (Plankton)," by William Crowder, NATIONAL GEOGRAPHIC MAGAZINE, September, 1927.