Paua—Opal of the Sea
BY AWAKE! WRITER IN NEW ZEALAND
Beneath the ocean a huge shellfish moves slowly across the rocks, grazing on seaweed that sways in the coastal currents. Its drab outer shell, encrusted with heavy lime deposits and tiny marine creatures, conceals an interior of iridescent colors—cool blues, sea greens, and inky purples that run into soft yellows and pinks, with flashes of gold and silver.
THIS amazing creature is a paua, an abalone unique to New Zealand. It and its abalone relatives live underwater around rocky shorelines. Although the paua is prized for the radiant colors of its inner shell, which can be made into beautiful jewelry, many consider its meat to be a delicious delicacy. In addition, lustrous pearls can be cultured within it.
The paua is one of the more than 100 species of abalones found around the world. South Africa and California, U.S.A., have their own species. The abalone is called awabi in Japan, muttonfish in Australia, and ormer on the island of Guernsey, in the English Channel. It is only in the cold southern waters of the South Pacific, however, that one can find New Zealand’s own brilliantly colored abalone, called paua (Haliotis iris).
A Biological Marvel
Within the paua’s shell, alternating layers of protein and calcium build up and refract iridescent colors much the way opals do. Thus, the paua has been given the name opal of the sea. A drop in sea temperature causes abalones to “hibernate” or go to sleep. The layers of their shells then take a longer time to grow. The variety in colors, one paua expert believes, may be the result of nutrients in the water as well as the different colors of seaweed the abalones eat.
Pauas are selective about their diet, and they are finicky about their choice of neighbors. They will not live near the spiny sea urchin, or kina, because it competes for the same types of seaweed. Also, the starfish is a dangerous enemy. A few of them can wipe out a colony of pauas. The crafty starfish puts a tentacle along the line of the paua’s breathing holes, thus suffocating it. Then, when the paua falls off its rocky perch, the starfish has an easy meal.
Multiple Uses for the Paua
Although the paua’s black outer appearance is not very appealing, for centuries the indigenous Maori of New Zealand have prized the meat of the paua for food. The edible part of the paua is a large muscle, or foot, by which the creature moves along its rocky environment. The Maori have also used its shell for fishing lures and decorations, as well as for jewelry and for eyes in their carvings.
The paua is now more popular than ever. A trip to New Zealand may hardly be considered complete without the purchase of some paua jewelry.
Today, divers—without any underwater breathing apparatus—are engaged in an extensive harvest of pauas. This has become a multimillion dollar export industry. To ensure the pauas’ survival in New Zealand waters, a quota system has been set. Most of the meat is canned for the Asian market, and some is frozen and sent to Singapore and Hong Kong, where paua is a sought-after luxury food. It is often served raw and sliced, sushi style. Despite the abundance of pauas in their waters, many New Zealanders have never tasted their meat because of the demand for it overseas.
To help meet the growing international appetite for paua, suppliers now use modern aquaculture. This man-made method of production has been successful with other abalones in Australia, Japan, and the United States. Such new techniques allow pauas to be cultured in temperature-controlled tanks far away from their natural marine environment.
Cultured pauas are just as voracious as their wild relatives. They can eat up to half their body weight each week. Surprisingly, pauas are also quite athletic. If they are turned over, they are able to flip back over quickly. Cultured pauas are easy to manage. One expert says that “pauas are lovely creatures to farm because they are so docile and well behaved—and they never answer back!”
In addition to being a source of shell jewelry and delicious food, pauas can produce lustrous pearls. Natural pearls rarely appear in pauas living in the sea. But they can be cultivated through the use of a technique first developed in the 1890’s by the French scientist Louis Boutan. The result is a gem hemispherical in shape that has the same spectacular colors as the shell. What is this technique?
The paua is seeded, usually in three places—twice along the side and once at the back. Gradually it will overlay these inserts with layers of nacre, or mother-of-pearl, which contains calcium carbonate and conchiolin. After at least 18 months—and thousands of layers—a small pearl is produced. (See the box below.) It takes up to six years for a large gem to develop. About 1 in 50 pauas will produce a nearly perfect pearl. This is a gem with a smooth surface, radiant color, and exceptional luster.
Researchers have still not been able to develop a round pearl from a paua. That is because, unlike an oyster, the paua has a muscle in its stomach that will spit out any bead placed in its digestive system. Perhaps one day someone will find the secret to creating that elusive spherical pearl.
In the meantime we can enjoy the products of this versatile shellfish—lustrous jewelry, an edible treat, and a shell of attractive colors. Are we not thankful to God for giving us such a delightful gift?—James 1:17.
[Box/Picture on page 24, 25]
A HEAVY-DUTY HOME
The main component of the paua shell is calcium carbonate. This material is also the stuff of which a stick of chalk is made. However, the shell of the paua has at least 30 times the strength of the chalk!
The paua draws calcium carbonate from seawater to make microthin plates of nacre. These make its shell not only extremely hard but also colorful and lustrous. The plates are bonded by a glue of protein and sugar called conchiolin. This powerful adhesive also adds to the mirror finish.
Scientists have been unable to duplicate the glue or the structural process. The shell can repair any cracks and has at least five different mechanisms for resisting breakage. Truly, the paua is a marvel of divine engineering and design.
© Humann/gt photo
[Picture Credit Lines on page 23]
Top left: © K.L. Gowlett-Holmes; top right: Marcus Byrne/Photographers Direct
[Picture Credit Line on page 25]
Silverdale Marine Hatchery, New Zealand