The Coast of Coral

by Arthur C. Clarke

  The muttonbird really makes its presence felt in the hours before the dawn. When, during our first night on Heron Island, we had finally dozed off and had ceased wor­rying about what absolutely essential items we had left on the mainland, we were awakened in the small hours of the morning by a din which we would never have believed birds were capable of making. A chorus of shrieks, groans, screeches, and twitterings came from the pisonia trees all around us, and no two birds seemed to be making the same kind of noise. Indeed, when that next morning I looked up the section headed ULULATION in Roget’s Thesaurus, I de­cided with reluctant admiration that of the forty-six basic animal noises the muttonbirds could provide good exam­ples of all except “buzz” and “hiss.”

  Oddly enough, the dawn chorus did not bother us after the first night. Since it seems unlikely that the muttonbirds had changed their habits just because we had arrived, this must be yet another proof of the way in which the human ears can adapt themselves even to the noisiest company.

  There are two ways, which really complement each other, of growing to know a coral reef. One is by walking over the exposed reef when the tide is out; the other is by diving, preferably around high tide. Only by diving, of course, can one explore the permanently submerged areas of the reef, which in many ways are much the most inter­esting. And only by diving can one hope to meet, literally face to face, the largest and most fascinating of the reef’s inhabitants.

  We soon found that any program we drew up for the systematic exploration of the reef was so much wasted ef­fort. A coral island is not, as most of the world imagines, a place of perpetual sunlight and crystal seas. It has weather—plenty of it. For days, even weeks, at a time it may be lashed by winds of hurricane strength, and drenched with torrential rains falling at the rate of an inch an hour. Even when there is no wind, and the sky is clear, the island may still feel the powerful influence of far-distant storms. It is a strange experience, on a lovely night when the sky is packed with steadily shining stars and there is not a breath of wind stirring among the trees, to hear a continuous roaring thunder as great waves that have been on the march for a thousand miles come smashing in against the reef. One almost expects, when the dawn breaks, to discover that the very foundations of the island have been swept away; but in the morning there will be no sign that energy equal to that of many atom bombs has spent itself in vain against the living ramparts of the reef.

  The underwater explorer is completely at the mercy of the weather; when it is rough, he cannot dive in safety, and even when the storm is past, two or three days may have to elapse before the disturbed water becomes really clear again. As often as not, the water will not have returned to normal before the next storm comes along to stir it up once more. Then there is nothing to do but to sit and wait, in the hope that tomorrow—or the day after—or the day after—will be better....

  We had planned to stay on Heron Island for no more than three weeks before moving further north along the Queensland coast. In that time, we optimistically calcu­lated, we should be able to obtain most of the photographs we needed. Three weeks, surely, was long enough to guar­antee a certain amount of favorable weather. We remem­bered Professor T. C. Roughley telling us that, when he was collecting material for his Wonders of the Great Barrier Reef, his island sojourn had coincided with a month of absolutely perfect weather. If we were a quarter as lucky as this, we would be reasonably content.

  As it turned out, we stayed on Heron Island not three weeks but six. And in that time we had perhaps four perfect days and about as many more which, from the underwater explorer’s point of view, were usable. The rest of the time it was overcast, there was a gale blowing, the water was dirty, or all three. It was the old story; by the end of the six weeks, which was the longest we could risk staying if we wanted to see the remaining twelve hundred or so miles of the Reef, we got more than a little tired of being told “You should have been here last season.” Toward the end of our visit we had ten continuous days when there was little point in stirring from our hut, and I shall never forget one night when the fusillade of the rain on the tin roof reached such a noise level that sleep was out of the ques­tion. In the morning some empty buckets that had been left outside were brimming with water, which was hardly sur­prising as according to the radio seventeen inches of rain had fallen in twenty-four hours. All this when the Wet had officially ended weeks before! As we rubbed the mold off our camera cases, we began to suspect the existence of a hitherto unrecorded phenomenon, which we christened the Damp.

  What increased, if possible, our frustration was the fact that from every other point of view the island was ideal. The reef was superb; we had the Research Station dinghy at our disposal; Mrs. Hasting looked after our meals and laundry, and, being a trained nurse, doctored our cuts and toothaches; and when any of our equipment went wrong, Eric Hasting would promptly fix it in his workshop. He had built an elaborate lathe-cum-drilling machine out of an astonishing collection of parts, including the undercarriage of a Kamikaze plane that had dive-bombed the ship in which he had served as a Chief Petty Officer in the Royal Australian Navy. There was nothing that Eric could not fix—except the weather.

  Despite this, our extended stay on the island produced worthwhile results, and when we finally left for the mainland we were not too disappointed. One day, we promised ourselves, we would return; and return we did, three thousand miles and two months later. The following chapters, however, are the record of our adventures on that first visit, when for me at least everything I met was fresh and strange. I was to see many other islands—some more beau­tiful and more romantic—but for the rest of my life the words “Great Barrier Reef” will always conjure up a certain submerged coral garden forty feet down and half a mile out from Heron Island.

  X

  The Stone Jungle

  Fossicking over the exposed coral, when the tide is out, is the most comfortable though least adventurous way of get­ting to know a reef. Even this is not without some hazards; it is necessary to wear boots, or at least thick sand shoes, since coral is dangerous stuff to walk on and inflicts cuts which may take a long time to heal. (As I type these words, I have a four-month-old scar which has failed to close completely despite penicillin, aureomycin, and several other “ins.”) And there is always a risk—remote, but nev­ertheless present—of accidentally stepping on one of the reef’s poisonous inhabitants, such as the dreaded stonefish, whose venom-tipped spines can cause an agonizing death.

  From a distance, when the sea has drained away, the exposed reef presents a somewhat drab and unimpressive appearance. Only a few boulders of dead coral, thrown up by the last cyclone, break the uniform flatness that stretches—perhaps for miles—toward the distant sea. It is not until you actually walk out among the rock pools and begin to explore this living tableland that you realize how much variety it holds. Tiny crabs scuttle away beneath your feet; fish trapped by the receding tide dart for shelter—but you hardly notice these dwellers on every seashore as you examine the fascinating shapes which only a coral reef can produce.

  Here is a giant mushroom, sunk in the sand. There lies the wrinkled replica of a human brain—there a forest of bifurcated branches resembling the patterns etched upon window panes by the frost that never visits these islands. Half buried in the rock is a partly opened clam, more than a foot across—a close relative, you realize, of the giant which is rumored to trap divers in its jaws. A gorgeous blue mantle fringes the gap between the shells, and as you approach, this exquisite welcome mat is hastily withdrawn. The clam must have sensed the vibration of your footsteps, for it jerks closed as you bend over it. You reach down and try to pry it loose from its rocky bed—and get a surprise as the agitated bivalve squirts a small geyser of water into your face. As you wipe your eyes, you decide that it is most improbable that any diver could get near enough to one of these nervous molluscs to be trapped by its jaws.

  If the reef has not been picked over by too many earlier visitors, you will find countles
s shells of all types and sizes. Many of them will have been vacated by their original inhabitants, but that does not mean that they are neces­sarily empty. You will often see one scuttling across the sand and, if you turn it over, will catch a glimpse of a hermit crab’s spidery legs as it retreats into the inner sanc­tum of its spiral home. Some of these crabs are very large—perhaps twelve inches long if stretched out straight, which they never are. The biggest specimens are colored a beautiful red, and have one outsized claw which they use as a door to seal their home against intruders. Sometimes it seems impossible that so much crab could squeeze itself into a relatively small shell.

  One of the commonest and most unmistakable creatures of the reef is the bêche-de-mer or sea cucumber, specimens of which may be seen lying in almost any pool. These repulsive objects, which often look like slimy black sau­sages, are sometimes two or three feet long. They can be seen feeding through the feathery tentacles which fringe their mouths, and if you annoy them they will sluggishly contract to half their original length, perhaps ejecting a mass of sticky, silken threads at the same time. In a real emergency the bêche-de-mer will abandon all its internal organs, hoping thereby to entangle or confuse its adver­sary. The fact that this animal lies around in the open, with no attempt at concealment, suggests that it had few natural enemies until some hardy Chinese decided that it made a delicious soup. Before the Second World War, a thriving industry exported dried bêche-de-mer to China at prices ranging up to a thousand dollars a ton.

  Some of the shells which may be found on the reef are of astonishing size. The giant clams have already been mentioned; Mike has seen one six feet across. One author­ity (Saville-Kent) quotes rumors of specimens fourteen feet long. Though it is tempting to dismiss such stories as typ­ical fishermen’s (or divers’) tales, some real monsters must exist in the unexplored regions of the Great Barrier Reef.

  There were none of the giant clams on Heron Island, but myriads of the smaller (only one or two feet across!) Tridacnidae. One of the most remarkable accomplishments of these bivalves is their ability to bore into the coral, so that it is often quite impossible to dislodge them without a crowbar. At first sight one might get the impression that the coral has grown around the clam, so snugly does it fit into its cavity. In actual fact, the clam bores into the coral by rocking to and fro—a method of excavation probably unique in the animal kingdom.

  The bailer shell must come next in point of size. It is the home of a mollusc not unlike a giant snail; one that I discovered weighed about ten pounds (with the animal inside it) and was over a foot long. It gets its name from the fact that it can be easily gripped by the hand and used as a readymade—though rather fragile—scoop for liquids.

  Dwindling down the scale of size are hundreds of other varieties of shell, many wonderfully colored and of exqui­site design. One—a small, truncated cone about two inches long—possesses a tiny, poisoned sickle with which it will try to stab you if you pick it up. The weapon has little range of movement, so it is quite safe to handle the shell if you know which is the end that bites. If not, it is best to leave it alone, for the stab is quite painful and has been known to cause death.

  Starfish of a vivid blue color, and sea urchins pricked out with curious beaded designs, are also very common on the reef. If you are lucky, you may find in a rock pool one of the most fantastically beautiful of all the creatures of the sea—a nudibranch, five or six inches long, looking like a gorgeously colored Persian carpet and undulating through the water with all the grace of a ballet dancer. No one can really believe in the nudibranch the first time he sees it in action. It is too beautiful, and too obviously im­practicable, to be true.

  Even at low tide, there are plenty of fish on the reef, though you may not see them. They will be lying hidden among the coral, and sometimes you may startle a fairly large one from under your very feet, both of you probably jumping out of the water in your mutual fright.

  If you know where to hunt for them, you can also find many crayfish lurking beneath the coral, their presence be­trayed by their long antennae. These armored and often marvelously colorful creatures, looking like lobsters without claws, provide excellent eating and were the main course in many nocturnal feasts while we were on Heron Island. Mike would sometimes bring back six or more—the largest almost two feet long—after a trip to the shallow pools in which they lived.

  To go fossicking successfully, you need bright sunlight to reveal the delicate colors of the coral, and a dead calm so that there are no disturbing ripples on the surface of the water. One of the frustrations which the reef can produce from its extensive repertory is a brilliant, sunny day with a ten-knot wind corrugating the water so thoroughly that nothing is visible through it, and you might as well be standing on the wrong side of a sheet of frosted glass.

  If you wish to walk out to the very edge of the reef, you have to choose your time carefully, setting out an hour or so before extreme low tide. A mile an hour is a good average speed over a reef; there are so many obstacles to overcome, and so many things to stop and examine. At first there will be extensive patches of open sand, littered with dead coral—an uninteresting desert whose only inhabitants will be the ugly bêche-de-mer. You will hurry through this without wasting any time, and soon you will find that the coral is encroaching upon the sand and is becoming more colorful and varied. You are entering the region of living coral, and very soon will have to scramble over its spiky palisades if you want to make any further progress.

  This requires a great deal of care, for much of the coral is brittle and will give way beneath your weight without any warning. The more massive, boulder-like corals are quite safe to walk on, but the fragile staghorns are treach­erous, and you can crash painfully through their branches with the greatest of ease. Though you will not fall more than a foot, you can easily cut your legs so badly that you will be out of action for several days. About halfway between the island and the reef edge the territory through which you are passing will be equally divided between shallow pools and flat-topped plateaus of living coral, pro­jecting a few inches above the water. I once had an odd experience in one of these pools, when a very decorative little shark swam right up to my feet and lay there mo­tionless for at least two minutes, exactly like a dog waiting to be patted. There was time to set up the camera tripod and take a couple of carefully composed photos before the shark got tired of my company and wandered off again.

  Near the very edge of the reef, the character of the coral begins to change. It becomes much more solid and close set, and accordingly much safer to walk upon. You have reached the massive rampart protecting the reef from the fury of the sea, which on all but the calmest days will be smashing its breakers against these living battlements.

  It is an unforgettable experience to walk along the very edge of the reef at low tide. Although you may be a mile from the nearest land, you will feel as secure as if you are walking on a concrete road. In many areas, indeed, the pounding of the seas will have welded the coral into a completely solid and almost smooth surface, which would require little treatment to convert it into a first-class highway.

  If the tide is still ebbing, a surprising volume of water will be draining off the reef flat and falling in cascades into the sea. These waterfalls at the edge of the reef are an unexpected and beautiful sight; in many places they will have cut what are virtually river mouths in the solid coral, which may be seen glowing in all its lovely pastel shades through the moving, crystal water. It seems quite surprising that such a large difference in level—often amounting to a couple of feet—can exist between the extensive pools on the reef and the sea with which they are connected through countless channels.

  On most days, even when the sea appears to be calm, there will be waves breaking in spray over the edge of the reef and you will not be able to look into the deep water beyond it. On rare occasions, however, the sea may be as flat as the proverbial millpond, or will have no more than a slow, oily swell upon its surface. Then, an
d only then, you can stand on the wetly glistening outer slopes of the coral rampart, and look right down into the blue waters that forever wash around it. The great flat shelf whose very limit you have now reached plunges abruptly into the sea. Behind you, stretching back to the island, will be the region that can be thoroughly explored with no more equipment than thick-soled sand shoes, but ahead lie mysteries that are never uncovered by the tide, and which only the diver can ever reach.

  Under ideal conditions, when the sea is flat, the water clear, and the sun high enough for its rays to pierce like blue-tinted searchlights far down into the depths, it is possible to see fifty or sixty feet down the coral-covered hillside. You will see legions of colored fish, most of them quite small, wandering to and fro along the edge of the reef, and darting for shelter when danger threatens. And further down, where the light fades and the thickening lay­ers of water veil everything with a penumbral mistiness, you may glimpse huge and shadowy shapes moving among the great boulders and through the aisles of the stone jun­gle.

  This aspect of the reef—the wide, massive rampart sud­denly shelving down into deep water—is typical of the parts which face the prevailing winds and which have, therefore, to withstand the violent storms which hurl themselves against the Queensland coast every summer. The sheltered, or lee, side is less rugged, and the transition zone which divides the reef proper from the deep water beyond it is considerably wider.

  On a clear, warm day one is reluctant to tear oneself away from the life and color at the edge of the reef, and to start the long walk back to the island. But if you delay your departure too long, you will suddenly realize that the countless clumps of exposed coral which lay between you and land are no longer visible. The tide has turned and slowly, stealthily, the water behind you has been rising as it seeps back through the myriad interstices of the reef. The little pools through which you waded an hour ago are now linking themselves together into wide lakes, and deepening minute by minute. Unless you want to swim—and share the water with the sharks which come in on the rising tide—it is time to head for home.