WAYS OF THE WILD.

Auckland Star, Volume LX, Issue 278, 23 November 1929, Page 1 (Supplement)

WAYS OF THE WILD.

A NATURALIST'S NOTEBOOK,

SHEIX FISH AS FOOD FOB MAN.

THE OYSTER.

(By A. T. PYCROFT.)

The oyster stands pre-eminent among shellfish as a food for man; it is not, however, found in cold 6eas. The one hundred species known are confined to warm and temperate seas. The cultivation of the oyster as a luxury of food dates at least from the gastronomic age of Rome. Everyone has heard of the epicure whose taste was so educated that '"he could tell at the tirst mouthful if.his oysters fed on the Rutupian or the Lucrine bed or at Circeii." The first artificial oyster cultivator on a large scale appears to have been a certain Roman named Sergius Orata, who lived about a century B.C. His object was not to please his own appetite so much as to make money by ministering to" the appetites of others. His vivaria were situated on the Lucrine lake, and the Lucrine oysters obtained under his cultivation a notoriety which they never entirely lost, although British oysters eventually came to be mare highly esteemed. He must have been a great enthusiast in his trade, for on one occasion when he became involved in a lawsuit with one of the riparian proprietors (Orata fortunately won), his counsel declared that Orata's opponent made a great*mistake if he expected to damp hia ardour by expelling him from the lake, for, sooner than not grow oysters at all, he would grow the molluscs in tanks on the roof of his house. Orata's successors in the business seem to have understood the secret of planting youn» oysters in new beds, for we are" told that specimens brought from Brundisium and even from Britain were placed for a while in the Lucrine lake to fatten after their long journey, and also to acquire the esteemed Lucrine flavour.

Hearts Beat After Being Swallowed. Some readers may be surprised to know that this marine animal has a heart. Mr. E. G. Boulenger, director of the London Zoological Society's aquarium', in a charming hook, "A Naturalist at the Dinner Table," states: "The oyster, like the weather, is a topic ever open to discussion among those who can appreciate the pleasures of the table." Some circumspection may possibly be necessary on such occasions when discussing the more intimate details regarding its structure and life history. Thus some of us will recall that delightful episode in "The Man from Blankley's," when at the dinner party the late Sir Charles Hawtrey as the hired guest paralysed the company by informing it that the hearts of the oysters that had been consumed would continue to beat for twenty minutes after they had been swallowed. Provided the oyster is swallowed whole there is a foundation of truth in the statement, for the mollusc's reflexes often continue long after the creature is actually dead "within the meaning of the act." burin flour summer months the oyster becomes "sick," a sickness unto life»,however, and not death. At that time of the Tear it produces between one and two million eggs, which are kept within the shell until they are hatched. - ~ Periodically Changing Its Sex. ■ These molluscs, whose scientific name is Ostrea (Latin, an oyster), have sometimes distinct and sometimes united sexes._ It has recently been established that it may experience as many as four changes from male to female within 13 months. On hatching, the larvae, or spat as they are called by the fishermen, are shot out of the shell into the water with considerable force, and the million or two baby oysters travel along the surface, resembling a smoke-cloud. An infant oyster placed beneath a microscope is revealed as a gelatinous mass encased between two transparent shells. From between the gaps of these shells there protrudes a row of cilia, or small vibratory swimming organs which lash the water with great fury, and carry the spat upon a perilous journey. A warm day, with little wind or tide, will permit some of the spat, when on the surface, running the gauntlet from its enemies, the larvae of fish, crabs, jellyfish, etc., who all regard the immature oyster a* a great delicacy. Should it run the gauntlet safely for 48 hours, it proceeds to sink to the bottom, and if it finds suitable anchorage, cements itself to some solid object. It then loses the cilia which were necessary for its swimming life. It begins to grow rapidly, increasing from about one-twentieth of an inch in diameter to about the size of a threepenny piece in five or six months, and in a year to one inch in diameter. An oyster grows at the rate of about half an inch in diameter a year for the first five years of his life, when he may be regarded as grown up. Many Enemies.

Such a succulent creature a« the orsiec has naturally many enemies. One oi the worst of these is the ravenous starfish, or five-ringer. Another dread enemy i* the whelCa term which includes several shells. Ail these species perforate the shell with the end of their radula, that i 5. the chitinous ribbon bearing the teeth of molluscs. The contents are then I sucked out through the neatly-drilled hole. The octopus is also a dangerous enemy. While the common mussel takes up room meant for the young oysters, it grows over the larger individuals, and harbours all sorts of refuse between and under its closely-packed ranks. The starfish's method of obtaining the oyster is by enveloping the bivalve in his arms, each of which carries several hundreds of suckers, and exerts a total pull which, has been calculated at 111b. At the same time an acid secretion is ejected between the valves of the mollusc. It may be safely asserted that less thau a dozen out of every family of a million survive to reach maturity. New Zealand possesses six species of oysters, the two well-known species being the rock oyster, found in the northern parts of the North Island, and the mud oyster, commonly known as the Stewart Island oyster. It is found in both islands, but it is mora common in the South, where, in Foveaux Strait and near Stewart Island, extensive beds occur at a depth of about 15 fathoms. Oyster farms are very extensive in England, France and America. The Whitstable farms in England extend over an area of more than 27 square miles. The principal of these is a kind of joint stock company, with no other privilege of entrance except birth as a free dredgeman of the town. When a holder dies his interest dies with him. Twelve directors, known as "the jury.'* manage the affairs of the company. The Colne beds are property oi the town of Colchester. The approximate value of the world's oyster crop has been estimated at the annual sum of close on .<;.">.000,000 sterling. The oyster is much valued by the Maoris, to whom it is known as tio. _