National Geographic : 1957 Jan
The National Geographic Magazine Another species may appear as an enormous purple-fringed disk lying flat on the bottom, elsewhere as a head of cauliflower or an in crustation of cabbage. Other corals resemble the convolutions of the human brain, the underside of a mushroom, the pipes of an organ, or a dainty gathering of lace. Diversity of form within the same species reflects the varying physical conditions of the tide-washed environment. The crashing surf at the outer edge of the reef encourages corals to grow into forms of tremendous mechan ical strength. The quiet of deep waters or protected pools stimulates delicate growth. Corals living on the walls of channels are modeled by yet other forces. Fringed Polyps Resemble Flowers Here and there we saw tentacle-fringed polyps-the true coral animals-each like a minute flower blossom. Their primary food is microscopic plankton, captured by myriad stinging cells that line the delicate tentacles (page 6).* The masses of coral we were observing were built up by infinite numbers of polyps, each one living in its own tiny limestone chamber and continually adding to it. Soft corals, most of which differ from the hard variety in their lack of a limestone exte rior and in details of anatomy, grow chiefly in the more placid waters. Found throughout the reef's shallows, soft corals are of leathery texture, slimy to the touch, usually somber in color, and often of great size. Another type of "coral" comprises the lime forming algae, which are especially notice able on the slightly elevated "pavement" near the edge of the reef. These are usually of some pink or rose hue and, although hard as rock, give the impression of having been poured like gravy into cracks and crevices and over the surfaces of old or dead coral. At the time of the very lowest spring tides, Heron reef appears as acre upon acre of high-and-dry coral-some living and some the dead limestone remains-suggestive of a plowed field, rather desolate and a bit for bidding. The farther out from the beach one presses, the larger and denser become the coral areas, and the more difficult it is to gain a foothold, until at last the growth fuses to form a more or less continuous crust, labyrinthed under neath, but nevertheless solid enough to walk upon. However, one must ever be mindful that coral is slippery and fragile, aware also of holes and crevices. In Brisbane I had talked with a well-known Australian ichthyologist who, on this very reef, had gone through the crust, painfully lacerating one leg nearly to the hip. All of ficial advice had been never to walk offshore without heavy shin-high rubber boots and puttees or leggings reaching to the knees. Agile Girl Braves Reef's Dangers Thus I suppose I should have considered more seriously the matter of taking a ten year-old child half a mile out on a remote Pacific reef where any misstep on the brittle and abrasive coral could have been serious. Yet, day after day, Virginia-with bare legs and nothing on her feet but a pair of thin tennis sneakers-bounded from one coral lump to the next with a most dainty indifference not only to the coral's sharp edges but to the deadly stonefish or the stinging cone shell and the sea wasp. Even my wife, instead of honoring my example in the use of pro tective armor, chose to follow Virginia's precedent (page 19). The ladies' impressively practical argument was that the lighter the footwear the less encumbered the fossicker and the more adroitly she could negotiate the reef. During the weeks of day-in, day-out reef work on Heron Island, none of us ever had even the slightest fall or mishap. The issue of armor versus grace, therefore, stands unresolved, at least in our experience. Deadly Stonefish Lies in Wait As to what one may encounter on the reef: The stonefish, a member of the scorpion fish family, is one of the ugliest monstrosities on earth. Gnarled, wrinkled, and warted so as to resemble a piece of dead coral or a dis integrating stone, the creature lies motionless in reef sand or alongside fragments of coral. If a foot approaches, thirteen deadly, needle sharp spines bristle vertically from the fish's back (pages 12, 13). Each spine has a pair of poison sacs near its middle and two grooves through which toxic fluid passes upward when pressure is applied. A bare or a lightly clad foot, pierced from its own weight by these hypodermics, (Continued on page 25) * See "Strange Babies of the Sea [Plankton]," by Hilary B. Moore, NATIONAL GEOGRAPHIC MAGAZINE, July, 1952.