Building Material of the Sea
BY “AWAKE!” CORRESPONDENT IN THE DOMINICAN REPUBLIC
NOW, is this not a wonderful way to relax? Sitting here on the white sand, a huge umbrella sheltering us from the sun, watching the waves trying to crawl up on the beach.
By the way, did you know that there is a big building project going on out there where the waves are piling up that white foam? No, there is no heavy construction equipment, no steel beams, cement blocks nor bricks. But out there the marvelous building material—coral—is being produced.
The underwater world of coral is a strange and beautiful world—strange in form and shape, beautiful in color and variety. There are brain corals of all sizes, so named because that is just what they resemble. There are flowerlike star corals, and those that look like staghorns or antlers. Also, there are lettuce coral, stinging coral and many other strange forms. Fascinating, too, are its colors—brown, yellow, orange, pink, purple and red.
Where the Material Is Found
Where could you go to investigate this marvelous building material, coral? To many places. You could visit the smooth turquoise waters of Montego Bay on Jamaica’s north coast, or travel elsewhere in the western Atlantic from Bermuda to Brazil. Another viewing area is the Indo-Pacific region, from the east coast of Africa, through the islands of the west Pacific to Hawaii. In this area one can see the Great Barrier Reef, a mass of coral extending some 1,250 miles along the northeastern coast of Australia.
In places one may be able to view the amazing building material of the sea through a glass-bottomed boat. Or one may choose to don flippers, a mask and air tank and go below to take a closer look. When entering the water, though, a person will want to accustom himself to the motion around him, for it seems that the seascape rises and falls in unison with the movement of the sea itself. One should also be careful, for cuts sustained on coral are very slow to heal.
How Coral Is Produced
The animals that make coral are called coral polyps. They are related to jellyfish and the flowerlike sea anemone. After a very brief free-swimming, larval state, these very tiny creatures settle down to a completely sedentary life, attaching themselves firmly on the skeletons of other coral animals.
Once rigidly settled, the polyps grow into a small fleshy tube, ranging in size from an inch to more than a foot in diameter. At their upper end is the mouth, surrounded by small tentacles. At night these extend out and capture microscopic planktonic animals for food.
At the same time, these little creatures are busy building. They take calcium from the water and secrete a calcium carbonate (limestone). Using this secretion, they build around themselves a hard, cuplike formation. This constitutes a coral house or skeleton into which they can retract for protection.
As many polyps build their coral houses, these fuse together to form a colorful, hard mass. The polyps die, but others attach themselves to their skeletons and continue to build. As a result, unbelievably tremendous edifices are raised, larger than anything man has ever produced.
What Is Built
Coral reefs are produced by tiny polyps. Some reefs extend from the shore into the sea. These are called fringing reefs. A barrier reef, on the other hand, is separated from the shore by water, but it follows the shoreline.
The world’s second-longest coral reef, after Australia’s Great Barrier Reef, extends 130 miles along the coast of British Honduras. Between the reef and the shore, water is from three to fifteen feet deep.
Coral makers also form atolls. These are ring-shaped coral islands in the open sea that encircle a body of water called a lagoon. An atoll may be formed as the coral builds up on the rim of the crater of a sunken volcano. Some of these atolls are inhabited. One in the Indian Ocean has an emergency landing field for jet airliners.
Thus the building of islands is not too ambitious a project for these tiny polyps to accomplish. The island of Barbados in the Caribbean, for example, is composed chiefly of coral. Gradual disintegration by water and weather has covered the coral of the island with a red clay soil.
Coral formations may grow in any ocean, but the reef-building coral polyps are confined to waters where the coldest temperatures do not drop below 65° F. Thus the remains of ancient coral reefs in Arctic waters indicate that a tropical climate prevailed in these northern seas at one time in the past.
While coral makers continue their prodigious task of building in the sea, other organisms such as parrot fish and angelfish bore into the structure or nibble at it, to weaken and crumble it. Sponges, seaweed and algae come to the rescue, cementing pieces together to prevent total disintegration. The result is a porous limestone with tunnels, caves and nooks.
History and Use of Coral
The Phoenician seaport of Tyre at one time was noted for her trade in coral. From the Mediterranean Sea a highly prized red coral was, and still is, harvested. It grows in small bushy formations and has a hard core that can be polished to bring out hues of red, rose or pink. It is then made into necklaces, bracelets and other adornments.
In Barbados and Bermuda coral is used in the construction of homes. It is easy to cut, and becomes hard and durable when exposed to air.
Possibly coral’s most important function, however, is the protection it affords coastlines from sea swells, tidal waves and hurricanes. Many a sea voyager has found safe anchorage during a tempest behind a coral reef.
As one reflects on the wonderful construction feats of such insignificant creatures, the handiwork of God, one cannot help but marvel.—Ps. 104:24.