Oyster

by Rebecca Stott

  Varieties of oyster. The names show attempts to make analogies with other natural objects: Ostrea frons or the leaflet oyster; O. retusa or the obsolete oyster; O. quercinus or the oak oyster.

  Eccentric oysters include rock oysters, giant coxcomb oysters, honeycomb oysters, thorny oysters and mangrove oysters. Pearl oysters come from a remote branch of the oyster family called Pteriidae, which are lined with the finest nacre or mother-of-pearl. The nacre is formed by the mantle of the oyster-shell, which extracts lime or calcium carbonate from the water; its function is simply to protect the soft flesh of the oyster from the rough shell. When a foreign object or parasite such as a bit of broken shell or grain of sand or a tiny worm, crab or fish gets inside the oyster-shell, the mantle secretes the nacre around it again to protect the soft flesh.

  Ostrea megadon or large-toothed oyster, and Ostrea rufa or rufous oyster.

  Ostrea crista or the gigantic oyster.

  Ostrea edulis or the flat oyster.

  A grouping of oysters: Ostrea permollis, O. ochracea, O. rostralis and O. talienwahnensis.

  For most oyster eaters, however, the differences can be divided simply into two categories: the Pacific oyster (Crassostrea species, which is generally larger and has an oval shell) and the flat (native) oyster (Ostrea species, which is smaller and has a rounder shell). The tastes are different; prices differ. Flat oysters are in great demand and more difficult to grow. Over the last century flat oysters have been struck by diseases and have been largely replaced on oyster-farms around the world by Pacific oysters or Crassostrea gigas. As the Pacific oyster spawns straight into the sea it can be controlled and cultivated more easily; in cooler climates the ‘spat’ or oyster larvae must be bred in artificial conditions and then transferred to the seabed.

  OYSTER LIVES

  The oyster is no butterfly or peacock. It has no bright colouring, plumage or charisma. Yet it is the most prolific and sexually fluid of all the sea creatures. Its fertility is a survival strategy, for whilst unimaginable numbers of oyster eggs and sperm are produced during the ejaculations of the oyster breeding season, each oyster that reaches an oyster stall or plate in a fine restaurant has done so against all odds, for only a few will survive the conditions of the seabed.

  Oysters spawning, showing the smoky ejaculations of the breeding season.

  The oyster ‘spat’ or larva in its various stages of development.

  Ostrea species and Crassostrea species have evolved to reproduce in different ways. Ostrea species eggs are fertilized inside the parent oyster and Crassostrea species eggs are fertilized outside as sperm and egg clouds meet in sea water. Whichever way, the young larva or ‘spat’ swims about freely for about two weeks, ‘his taste of vagabondage, of devil-may-care free roaming’, writes food author, M.F.K. Fisher. She continues:

  A bunch of oysters, showing growth of mussels and barnacles.

  A set of oysters on a shell, showing crowding.

  And even then they are not quite free, for during all his youth he is busy growing a strong foot and a large supply of sticky cementlike stuff. If he thought, he might wonder why . . . The two weeks up, he suddenly attaches himself to the first clean hard object he bumps into. His fifty million brothers who have not been eaten by fish may or may not bump into anything clean and hard, and those who do not, die. But our spat is lucky, and in great good spirits he clamps himself firmly to his home, probably forever.5

  ‘Home’ in the wild may be a rock, a mangrove tree, the post of a pier, even the shell of another oyster. In the nineteenth century a Mr Payne of Blackheath put together a collection of objects on which oysters had grown. These included a seventeenth-century champagne bottle thrown from the wreck of the Royal George, a Chinese teapot without a spout dredged up from the Falmouth River, inside which the oyster had grown to enormous size, and several old sea-saturated boots.6 If the oyster is a cultured oyster born into an oyster-farm, ‘home’ (the cultch laid down for the oysters to attach to) will depend upon where it is in the world: in France, for instance, it may be a lime-coated tile; in Japan, a submerged bamboo wigwam; or in a Norwegian sea fjord, it may be bundles of suspended birch twigs.

  Oysters growing on a stone.

  Oysters growing on an old boot.

  Seed oysters on a cultch, the flooring of an oyster-bed.

  From this point, now firmly anchored, he devotes himself to feeding, pumping litres of seawater through his body and simultaneously straining it with his gills for plankton and other small organisms. For a human this would mean drinking the contents of 62 bathtubs every hour, or the contents of a large swimming pool between one dawn and the next. The water is pumped through the body by means of tiny hairs or cilia: ‘a ciliated surface’, writes C. M. Yonge, ‘resembles a field of corn blown by the wind with waves of movement passing over it in the direction of the effective beat’.7

  I use the masculine pronoun, as Fisher does, with some hesitation, for the oyster is never quite sexually fixed. It is generally assumed that for the first year at least, the oyster is male, and fertilizes a few hundred thousand eggs in his first summer. But ‘he’ matures into femaleness: ‘one day, maternal longings surge between his two valves in his cold guts and gills and all his crinkly fringes. Necessity, that well-known mother, makes him one. He is a she.’8 But since around 50 per cent of the oyster population is female at any one point of the season, the female oyster must turn back to maleness from time to time.9 It is now estimated that the oyster may change its sex up to four times a year controlled by some mysterious synchronicity or the vagaries of water temperature or salinity. Perhaps, with all that seawater pumping through its body incessantly, it is at least poetically appropriate that it should be as sexually fluid as this. Ogden Nash wrote in 1931:

  Oyster gills filtering seawater for plankton.

  The development of the oyster.

  The oyster’s a confusing suitor

  It’s masc., and fem., and even neuter.

  But whether husband, pal or wife

  It leads a painless sort of life.

  I’d like to be an oyster, say,

  In August, June, July or May.

  The adult oyster has no head, limbs, eyes, nose, jaws or teeth, but it has a highly tuned sensory system that works like a radar and its anatomy, the nineteenth-century marine zoologist T. H. Huxley wrote, is ‘greatly more complicated than a watch’.

  Its body is shut between two concave limestone doors, which are hinged at one end, like a long cheque-book bound together at the back. An adductor muscle at the hinge opens and closes its shell and acts as a double locking device. Its radar system is sensitive to the slightest movement and dredgers report that even the shadow of their boats passing over oyster-beds will make them close up their shells. The shell increases in size and thickness season by season as the oyster secretes successive layers of pearlized lime over its inner surface, each layer no thicker than tissue paper. At three years old it is large enough to be eaten.

  The oyster’s radar and defensive mechanisms are critical for its survival, for mouths other than human mouths hunger for oyster flesh. Oysters have several principal predators: the starfish wraps its arms around the oyster, forces its shell apart and ingests it; the boring sponge bores tiny holes in its shell, honeycombing it with tunnels; the slipper-limpet and the mussel smother the oysters or starve them by attaching themselves to an oyster’s shell and eating all their food; the dog-whelk and the whelk-tingle also bore into the shell and suck out the flesh. The oyster, beset by such enemies, writes M.F.K. Fisher, ‘lives motionless, soundless, her own cold ugly shape her only dissipation, and if she escapes the menace of duck-slipper-mussel-Black-Drum-leech-sponge-borer-starfish, it is for man to eat because of man’s own hunger’.10

  This set of six German cards was given away by the Liebig Extract of Meat Company (LEMCO) in the 1950s.

  Starfish attacking oysters.

  And if oysters have slowly evolved successful defence strategies to keep hungry predators
out of their shells, their most ingenious predators continue to find new ways of getting in. Astonishingly, the French aquaculturist Yves LeBorgnes invented a mechanism for breeding oysters with pull-tabs in 1996. The pull-tab, called a ‘Fizz’, consists of a plastic tab connected to a loop of stainless steel wire. The wire loop is threaded by hand around the anaesthetized young oyster’s adductor muscle, which holds the shell closed. When pulled, the wire acts like a noose, slicing the muscle. Tug the tab and the oyster falls open. The pull-tab oysters, however, are not yet economically viable nor do they seem to have even a potential market amongst oyster eaters, for whom the struggle to reach the fiercely defended flesh inside the shell is apparently an integral part of the gourmet encounter of man and oyster.

  2 Oyster Culture

  Florus . . . Who can fill the Thames with ships and merchandise? Rome: only Rome. There is only one civilisation in the world. Bring Britain into it and she will grow and prosper: count for something, be alive. Shut her off into herself, and what is she? An island off the coast of Gaul, celebrated – for its oysters. Lawrence Binyon, Boadicea (1927)

  STRANDLOPERS AND SHELL MIDDENS

  Archaeologists have found shell middens, extraordinary mounds formed by sea shells accumulated over millennia by early human settlers, along Scandinavian shorelines and down the west coast of the Americas from the Bering Strait off Alaska to British Columbia, California, Mexico, Peru and Chile. They are almost always packed with oyster-shells. In Japan shell middens are horseshoe-shaped and cluster around a central area of occupation. In Jutland they are elongated and stretch along the shoreline for 600–700 metres. In Portugal they are as high as five metres in some places.1 To the East of Texas, middens cluster along the Gulf Coast all the way to the Florida Keys. The two oldest-known shell middens in Texas are located near Galveston Bay and are the remains of Native American campsites from 3,500 years ago. Some of these shell middens date back to around 40,000 to 12,000 years ago (the Upper Paleolithic), a period in which archaeologists believe that human diets broadened significantly.2 And shell middens are not just a thing of the past – some hills of shells are still being built outside oyster shucking plants around the world.

  A postcard showing a large mound of shells outside an oyster shucking plant in Virginia.

  Oyster-shell reefs have also formed islands on which humans have built their homes. In Senegal, on the coast south of Dakar, for instance, there is an island called Fadiouth joined to the mainland by a bridge; this is actually an archipelago formed over millions of years by the shells of mangrove oysters, oysters that grow on the extensive tree roots of mangrove trees. The people travel from one island to another and fish for oysters by canoe, paddling across a lagoon paved with oysters, and lined by baobab trees which feed on calcium. The streets are lined with oyster-shells, and in the cemetery, Muslims and Catholics are buried under startlingly white oyster-shell mounds in the shade of the mangrove trees.

  An oyster midden near Florida, 1915. The ancient oyster beds have formed an island, called Turtle Mound.

  But what can shell middens tell us about early humans? The fact that oyster-shells are found in the old Danish kjokkenmoddings shows not only that they were eaten here at an early date but also that oysters once grew abundantly along the coastline of the Baltic, which now lacks sufficient salt to support them. Studies of Danish shell middens show that oysters were harvested during the extreme spring tides of March and September and were mostly roasted in the embers of fires to open their shells, but may also have been dried or smoked. By dating the shells archaeologists have also discovered that some time between the Mesolithic and the Neolithic in the Stone Age, the shell middens change in content from being mostly oysters to being mostly cockles. This is evidence that there was probably a sea regression at about this point in the estuaries and bays in which these people lived, which would have reduced the salt content and thus the number of oysters. It may also mark a shift from a hunter/gatherer/fisher culture to a more agricultural one.

  Shell middens are found along the southern African coast, in the open and in caves. They are made up mostly of shellfish shells, but also contain the bones of terrestrial animals, such as hippopotamus, buffalo, birds, tortoises and snakes, and are believed to be the relics of communities of ‘Strandlopers’ (beachcombers), in particular the ancestors of a hunter-gatherer tribe called Khoikhoi or Khoekhoe who occupied most of the coastal region from beyond the Orange River to the eastern Cape. Their ancestors farmed and fished along this coast for at least 2,000 years and their descendants still inhabit the region. Johan Albrecht von Mandelslo, who visited the Cape in 1639, called these people Watermen because they lived near the shore, and Leendert Janssen, a survivor from the Harlem wrecked in Table Bay in 1647, called them ‘Strandlopers’. For some time it was thought that these tribal peoples ate only shellfish, but recent evidence of the shell middens shows that their diet changed from season to season, depending on what meat was available.3 In the winter oyster flesh, roasted over a fire, supplemented the more scarce hippopotamus or tortoise meat.

  OYSTER-BEDS

  At some point in human history, men and women turned their minds to cultivating oysters artificially as a way of controlling and increasing their supply. The first people to do so were almost certainly the Chinese; China still produces over 80 per cent of the world’s oysters. An ancient Chinese treatise entitled Fish Breeding suggests that aquaculture was already in a developed state in 475 BC, but few Chinese records remain.

  The most extensive records of early oyster cultivation are those of the Romans. Pliny describes the very first artificial oyster-beds which were laid by a Roman entrepreneur, Sergius Orata, at Baiae just after the Marsic War in 95 BC. Orata seems to have made his money by ambitious water-engineering schemes, for he is also reputed to have invented shower baths. Valerius Maximus described Orata thus:

  unwilling to leave his palate under the control of Neptune’s caprice, [he] devised special seas for himself by cutting off the water by means of channels to catch the tide and shutting in various kinds of fish, keeping the molluscs apart so that not even the strongest gale could penetrate. And in this way even lightly-laden tables abounded in a variety of little fishes.4

  Close to the oyster-beds Orata built a palace where he threw long and decadent parties, feasting through day and night. At every feast thousands of oysters were consumed, only to be politely regurgitated by means of peacock-feather throat ticklers in a room adjoining the banquet. Seneca famously wrote: ‘Oysters are not really food, but are relished to bully the sated stomach into further eating.’ As oysters became more and more central to the gourmet lifestyle of those living not just in Rome but also in Roman seaside villas, new owners built their houses with salt water tanks of their own. L. Cornelius Lentulus in 50 BC described the menu of a feast:

  Before dinner: sea urchins, raw oysters ad libitum, pelorides, spondyli, the fish turdus, asparagus. Next course: fat fowls, oyster patties, pelorides, black and white balani. Next course: spondyli, glycymerides, sea anemones, beccaficos, etc. etc.5

  Another Roman banquet is described in Becker’s ‘Gallus’:

  Around stood silver dishes containing asparagus, lactuta, radishes and other representations of the garden, in addition to lacerta, flavoured both with mint and rue, and with Byzantine muria, and dressed snails and oysters, while fresh ones in abundance were handed round. The company expressed their admiration of their host’s fanciful invention, and then proceeded to help themselves to what each desired, according to his taste. At the same time slaves carried round in golden goblets the mulsum, composed of Hymettian honey and Falernian wines.6

  The oyster became the caviar or white truffle of the Roman table, sought far and wide or delivered from Orata’s artificial beds. Slaves were sent to the sea coast of the Atlantic to gather them. Ever resourceful, the Romans also discovered that ground oyster-shells could be made into ointment to cure wounds, ulcers and chilblains. Oyster-shell powder formed a hard smooth ce
ment for road surfacing or, mixed with figs and pitch, could be used to repair the Roman baths. The oyster had become embedded in the activities of the Roman Empire: in its feasts, its roads and its baths. But it was not until the Empire had reached Britain that, around AD 78, the first oysters were gathered from the shores of Kent, at Richborough (near Whitstable), and carried back to Rome, packed in sacks of snow, so that the shells were held together, where they created a new passion among Roman gourmets. ‘Agrippa’, writes Bolitho, ‘swept Lucrine oysters off the table, and enthroned the British oysters in their place’.7 British oysters had become the ‘new black’ in Rome.

  Hector Bolitho claims that ‘when Rome shivered and became dust, other civilizations took the oyster to their heart and loved it and ate it. And as the art of cooking moved from the crude fire in the open to the refined science of the kitchen, the oyster fired the imagination of cooks and gourmets, until oyster eating could almost be looked upon as a mark of civilization.’8 Since the Roman and Chinese established their oyster-beds, oyster cultivation has evolved, like the oyster, in scores of different ways, oyster farmers adapting to the conditions of local estuaries and experimenting with local materials to use as cultch. By the beginning of the twentieth century, oyster cultivation was firmly established around the shorelines of the world. An entry in an encyclopaedia for 1911 reads: ‘Oysters are more valuable than any other single product of the fisheries, and in at least twenty-five countries are an important factor in the food-supply. The approximate value of the world’s oyster crop approaches £4,000,000 annually, representing over 30,000,000 bushels, or nearly 10 billion oysters. Not less than 150,000 persons are engaged in the industry, and the total number dependent thereon is fully half a million. The following table shows in general terms the yearly oyster product of the world.’