MAN and SHELLS: Molluscs in the History

Molluscs show an architecture designed by an inexhaustible imagina-tion, shapes and designs that have been and are still a marvel for all, and a source of inspiration for artists of alltime. But not only that: science, literature, jewellery, handicraft, and, of course, gastronomy owe much to the molluscs, the shells’ pro-ducers. They include forms very familiar to us, such as the garden snails and the octopuses, mussels and oysters, clams and squid and appeared on our planet long before Man, approximately 500 million years ago.

At some point, they crossed the Man, playing an important role in our life. Many molluscs, in fact, have become part of the human diet from the beginning of our cultural evolution, while others become natural containers, and their uses were in-numerable. Some shells have dominated among the talismans for centuries, some-times as special witness of religious pilgrimage, or represented money in three continents for more than half a millennium. Moreover, the whelks, the Triton trumpets, can be considered one of the first communication instrument at the glob-al level, while, other molluscs, like the Mediterranean Bolinus brandarisand Pin-na nobilis, producing purple and byssus respectively, have had an important role in the history of clothing.

Finally, the contribution that molluscs have provided and continue to give to the experimental biology as well as in mathematic studies is great and, since the clas-sical ages, theyare also part of literature and were, sometimes, protagonists even at cinema and in music.

In all cultures, people wore and used shells for decoration, or religious purposes. The oldest recorddates backto about 500,000years ago, and sincePalaeolithic, no human grave was found without ornaments made with shells. Over time,some shells even assumed magicalproperties, often linked to the mysteries of conception, birth and femininity: a symbolism summarized in the myth of Aphrodite, the Goddess of Love.

The tradition of putting one or more shells in the mouth or on the eyes of the dead has been well-known in China as well as in Europe, later adopted by the Greek and Roman cultures. This tradition, so surprisingly common in many tra-ditions, recall the two fundamental attributes that Man has given to some shells: religious symbol and economic value.

One shell above all, the scallop, the shell of St James, has assumed an absolute importance, intertwined with the history of Christianity: it is the symbol and wit-ness of the pilgrimage to Santiago de Compostela. This shell often accompanied the Christian in his grave, according to a millenarian tradition. Other shells, mainly pearl oysters, were the witness of the pilgrimage of Muslims to Mecca, while various religious beliefs, in some way, involved shellfish: in Sicily, with the tradition of, as well as in England, with the legend of.

Finally, some molluscs can produce the pearl, an extraordinary symbol of perfec-tion, beauty, and vitality. According to an old tradition, in fact, the pearl has the power to preserve beauty and sexual desire.

Since archaic periods, shells were used to produce sounds in many cultures. The conch-trumpet is a musical instrument among the most universal, and at the same time, the most durable. Over the centuries, whelks have become widespread in many Mediterranean populations, andalso in Indo-Pacific and in almost all of the Americas, even in distant lands over the sea. Of course, there were different shells for different cultures: Charonia lampasin Mediterranean, the “chank” Turbinella pyrum,considered sacred inIndia, the horse conch Pleu-roploca giganteaand Strombus gigasin Americas, Cassis cornutain the Indian Ocean, and Charonia tritonisand Syrinx aruanusin the Pacific Islands.

According to Greek myths, the whelk sounded the end of the Universal Deluge, while in central Europe, the custom of playing it in the wind, during a storm, survived until to the 20th century.

The whelk is not just a musical instrument popular in many cultures and in many historical periods, but has also achieved a prominent place in the arts, as Triton, son of Poseidon, plays a whelk to announce the end of the Deluge.

Shell-rattles, such as “maracas” and “castanets” sounding by shack or percussion, were mainly used in magic rituals by shamans and sorcerers: their sounds ac-company ritual dances, marking the beat, or as rattles, to amuse children.

Shells, often small sculptures of extraordinary elegance, are a contin-uous source of inspiration since 20,000 years ago, when a Cro-Magnon man carved a stone to simulate the turns of a shell. Crossing the Mediterranean Car-dium Cultureto the Aegean culture, artists were mostly inspired by the sea and its inhabitants.

The spiral shape of the gastropods has been adopted by all the towers in the world, starting from the legendary Tower of Babel, while several architectonical styles (Manueline Style, Baroque, Rococo, Neo-Baroque, Liberty) used many forms which refer to marine organisms, and in particular to shells.In the Renais-sance, the shells of many molluscs (Nautilus,Argonauta, Pecten, Tridacna) be-come models of inspiration. Nautilusshell become a key element in jewellery too: the Nautilus cups,with gilded silver, gold, and semiprecious stones, will be-long forever to the history of art, thanks to the genius of Cellini. At the beginning of 1600, shells were one of the most common subjects, especially in Flemish paintings, and were sometimes protagonists in 19thcentury romantic paintings.

Even some 20thcentury architects were inspired by shells, reinterpreting the eternal forms of Nature, according to different philosophies and approaches. We have to remember Leonardo da Vinci, Antoni Gaudí, Le Corbusier, Frank Lloyd Wright and Jørn Utzon. As architectural elements, shells also became important during the 16th century, especially in the implementation of the nymphaeum, fol-lowing the classical tradition of a peaceful place consecrated to nymphs.

Since Palaeolithic times, the shells of the molluscs, eaten as food, then became small pots or were used to make necklaces, neckbands, bracelets, ear-rings, or to decorate objects. People used shells available in nature: tusk shells, cockles, scallops in the Mediterranean, abalones, clams, and thorny oysters in Americas, cones and cowries in Africa, pearl oysters and cones in Polynesia. Still today, abalones in New Zealand still adorn many objects with their iridescent na-cre.

Many American Indian tribes used mussels, scallops, and clams, queen conch or whelks to create scrapers, knives blades, spoons, while the columellaof the larg-est gastropods was used to make earrings. In the Pacific area, the Puka shell jew-ellery, the use of worked shells to create ornaments, is widespread.

Bivalve valves have been and are still being used as a support for small paintings both in Asia, in America and Europe. Of course, the value of these small paint-ings depends on the ability of the artist: in Maine (USA) it is still common to decorate the Christmas tree with painted oyster and scallop shells.

The use of shells to achieve the most varied compositions became widespread especially among sailors. At the beginning of the 19thcentury, especially in Bar-bados, Sailor's Valentinescame into fashion: they were wooden tablets, generally octagonal in shape, which show romantic designs and emotional expressions by gluing small shells. Those sailors wore them as gifts from their beloved.

Shells have been used for at leastfour millennia as a bargaining chip in China and Europe, and when metal coins became popular, they were often re-produced on them. The profile of a cowry, a shell always linked to the concept of money, appeared on the first coins of the Western world around the 5th -4th centu-ry BC. The combination of shell and money is therefore very old and many shells, or rather parts thereof, were assembled to form necklaces and belts having a certain monetary value.

They acquired important symbolic and anthropological values, also very much related to social relationships established between various communities.

Cowries are the shells that summarize the concept of money and undoubtedly they played a key role in trades in Africa and in some areas of the Indo-Pacific. This traffic was mainly handled by Arabs, who held it for nearly 700 years. At the end of the 16th century, cowries were an important sign of the wealth in many Western African kingdoms and the basis of the slave trade.

The North America natives knew, for thousands of years, how to work any type of shells, also using them as money: the famous “wampum”. Strings of wampum were also used instead of writing, and were created to record important treaties and historical events. Even the ethnic groups from the Pacific coast of North America have their shell currency, adopting the elephant tusk-like shell, stuck in long rosaries, the “haik-wa”.

The pearl, a rare product of some marine and freshwater bivalves and gastropods, has been considered a talisman of fecundity, and become symbol of perfection and absolute purity in many cultures. Greek symbol of love, the pearl also took several religious significances, and remain one of the principal orna-ments of the crowns of many royal houses.

The pearl is linked to love, but at the same time, to pain: this is a concept still present in the collective imagination and according to popular belief, pearls lead not only love, but also tears for their owners.

The most famous pearls, but not always those with the greatest value, are due to different species of pearl oysters, living in the Red Sea and Western Indian Ocean as well as in Australia, and Central America. The areas of great tradition for pearl fishing were the Persian Gulf, Red Sea, the Gulf of Mannar in South India, Sri Lanka, Madagascar, and the Malay Peninsula.

With the discovery of the New World, pearls of great beauty were found in thwaters of the Gulf of Mexico and along the coast of Venezuela as well as in the Pacific Ocean, in particular, from Australia to French Polynesia and Philippines. In any part of the world the pearl fishing occurred, it has been a story of destruc-tion. Thediscovery of pearl banks in the tropics provoked, in fact, a kind of “gold rush” in a very short time, with a devastating exploitation not only of the banks themselves, but of the natives themselves.

Some gastropods are capable of producing a pigment, the purple dye, which has been widely used in the past to dye a lot of different materials, while some bivalves can produce byssus fibres used in the past to make a very fine tis-sue. Cephalopods, octopus, and cuttlefish produce, thanks to specialized glands, a black pigment which is released in cases of danger to confuse the aggressor and promotes their escape: for centuries, it was used as ink, but is also appreciated in cooking pasta and rice.

In the Classical Age, Phoenicians were certainly the first and probably unique historic producers of purple, while in the Middle Ages, the pigment used at the Court of Charlemagne, was probably extracted by Britons from Nucella lapillus, a common gastropod from the North Sea. Little by little, this dye fell into disuse and around the 16thcentury, the dye shops in Europe were no longer be able to continue the ancient processes developed by the Phoenicians and the use of pur-ple was lost forever.

Many bivalves, but overall, the Mediterranean Pinna nobilis, can produce silky filaments, the byssus, a set of keratin filaments which can be processed to realize rare and filmy tissues of a nice golden brown colour. For many centuries, the byssus tissues were a hallmark of command and power, and were reserved to no-blemen and important members of the Church in Rome.

The passion to collect shells arose in the Upper Palaeolithic, and at-tended all the cultural evolution of Man. The breakthrough will come in the 16th century with the beginning of the great geographical explorations: the first large shells from the South Seas and the Caribbean which came in Europe received an immediate and resounding success. Beautiful and rare, and thus highly sought af-ter, they began to enrich the collections of Naturaliain the Wunderkammern,ex-traordinary places, filled with collections of a disparate and chaotic expression of richness which arose in all courts of Europe.

The mid-19thcentury is called the Golden Age of Conchology thanks to Hugh Cuming ,who began to collect shells, especially in Chile and Argentina, and after from Easter Island to Polynesia and Philippines. At his death, a huge collection of nearly 53,000 shells of 19,000 species remained, that the British Museum bought.

The shell collector has an unrealizable ambition: to hold all the shells of the world. Conscious of the impossibility of realizing this dream, he often specializ-es in one group (generally a family). Today, the greatcollectors particularly ap-preciate some families of gastropods, especially the cones and cowries, whose shells are very smooth, with porcelain surfaces. Other families much sought after are volutids, olivids, terebrids, mitrids, muricids, strombids, cassids, cimatids and harpids. Bivalves arouse less interest, although thorny oysters and scallops are, perhaps, the only two families really appreciated worldwide. Recently, the interest of collectors was also directed towards the shells of molluscs living in deep waters, below 1,000 meters depth, as the pleurotomariids, primitive gastro-pods characterized by a long slit that runs through the last whorl of the shell.

Even many fossil molluscs are appreciated: some ammonites arouse considerable interest and can achieve amazing prices at the auctions.

At the dawn of civilization, Man was an active consumer of bivalve. Fishing is in fact one of the most ancient human activities and it is easy to imagine that the Palaeolithic man, arriving to the coast, quickly learned to recognize and appreciate limpets, mussels, clams, oysters, and other edible shellfish, easily to find along the shore.

The numerous shells, and not just marine, which are found today in heaps of waste(kitchen middens), leftovers of prehistoric dinners, emphasize the importance of shellfish as a food source for humans.

Virtually, all shellfish are edible and for many centuries were a tasty source of cheap food.

The oysters are certainly the “queen of shellfish”: their taste, delicate or strong, varies depending on the different species, the area and quality of the waters. Also mussels are great "sea food": more humble than oysters, are very tasty. Moreover, scallops are much appreciated all over the world, and represent one of the main food products everywhere, especially in cold temperate zones. In addition, in many parts of the world, several bivalves, such as clams, cockles, razor clams and donacids are sought afterand appreciated.

Some gastropods are very popular in the kitchen of different people, and abalones, muricids, and winkles are very much appreciated. Cuttlefish and squid are also important sources of food in some regions and could become one of the main sources of protein in the coming decades.

The bivalve farming started in Europe during the Roman period and probably before in Asia.

At the end of the 19th century, the consumption of molluscs became very popular everywhere, while the use of motor boats, with which fishermen could dredge more easily and deeper, quickly destroyed the natural beds of oysters and mussels on both sides of the Atlantic. Moreover, the pollution of water, especially in estua-rine areas, following the industrial revolution, also contributed to their destruction. It was clear that if people wanted to continue to consume large quantities of bi-valves, it was necessary to begin to farm them.

Today, if we exclude a small number of land snails, only marine bivalves (mainly oysters, clams, scallops, and mussels) are farmed with great success, utilising methods sometimes old of centuries. Typically, shellfish farming is considered "environmentally friendly" as molluscs are not artificially feed, and consequently no surplus of organic substances is added to the environment.

Since 8,000 years ago, some land snails have been an important source of protein for humans and their roasted shells are often abundant throughout the Mediterra-nean region. During the Republican period, Romans farmed them with great suc-cess. At the beginning of the 19thcentury, land snails became a “must” in the French cuisine (and therefore in the world), and today some species of snails are farmed in different countries both in Europe (Italy, France, and Spain) and in trop-ical countries.

In the mid-19thcentury, European and North American shellfish farmers began the search for "new" bivalves of potential commercial interest, suitable for farming and more resistant to epi-demics. Some of these imports have had great success (like the Japanese oyster or the Philippine clam), but often this kind of trade has caused serious problems: the introduction of a species in a "new" environment is, in fact, a high ecological risk action. It is, in fact, clear that the continuous transport of stocks of living organ-isms from a production area to another, practically all over the world, favours the spread of pests and the diffusion of invasive species which may cause damage to economic activities and in par-ticular to aquaculture. Moreover, in the Mediterranean Sea, the Su-ez Canal has facilitated the spread of numerous molluscs which, over time, have created stable Mediterranean populations, entering sometimes in competition with the native flora and fauna.

In freshwaters, the most famous case is the diffusion in Western Europe and North America of the zebra mussel, an invasive bivalve which causes very serious economic problems, obstructing indus-trial and civil pumping water stations in lakes and rivers.

Some molluscs and their fossils entered in ancient myths and legends in the culture of many peoples. The most famous of them is the kraken, the legendary sea monster that sailors believed capable of attacking and sinking ships. Today, we know that giant squids (Architeuthis) really exist in the depths of the oceans, buttheir meetingis very rare.

If we exclude the myths, few truly dangerous molluscs exist: nevertheless, some species should be handled with extreme care, like the venomous cones or few species of tropical octopuses.

There is no known bivalve dangerous in itself, but they can, if ingested, become poten-tial carriers of pathogens and toxins, causing intestinal disorders and intoxications. Moreover, some terrestrial and freshwater gastropods, especially in tropical areas, are intermediate hosts in the complex life cycles of many flatworm parasites of man, such as flukes and tapeworms. Absolutely innocent, these small gastropods are carriers of se-rious diseases such as fascioliasis.

Some marine bivalves, like ship-worms (Teredo), are able to drill, using acid secretions, wood, claysand carbonate substrates, whose action cannot be underestimated, because it has often resulted in serious damage.

Some land snails and slugs, when introduced into alien environments where there are no natural predators, can create real havoc. The giant African snail (Achatina) is a very ag-gressive pest. In general, many snails are harmful to agriculture, because they attack the more tender parts of plants useful to man, and they can also spread infectious diseases between horticultural plants.

Due to the heavy impact of the human activities, a generalized habitat depletion, with loss in terms of biodiversity, biomass, and structural complexity, has been recorded everywhere in rivers, coastal waters, estuaries and lagoons. Molluscs have suffered and are suffering of this pressure and in the more polluted environments only the more "robust" species are able to adapt to these conditions, but the loss of biodiversity both at sea and land has been very serious.

The exploitation of limpets, mussels, oysters or other marine bivalves, living in the coastal zone, has been significant in the last two centuries, and trawling gears, like dredges and bottom nets, caused serious structural changes in all exploited benthic communities, putting in jeopardy the existence of various habitats and many species.

Today, many molluscs of commercial interest at risk of extinction are reported in CITES appendices, the UN organisation which controls and regulates trade of wild fauna and flora, trying to prevent the exploitation of endangered species. However, controls are often lack-ing and very often many molluscs are still harvested indiscriminately. Other species, not yet taken into account, must be protected as soon as possible: in the fight against the loss of bi-odiversity, it is necessary to take actions that they will not only protect a particular species, but the whole environment where the species lives. It is also urgent the protection of the fossil deposits which are full of shells, often of great collection interest.

The establishment of parks and protected areas, and an international legislature that manag-es the marketing, seem today more necessary than ever for the protection of the living and fossil molluscs.

Molluscs have played an important role in the history of science. They inspired models in mathematics and geometry, or were protagonists of the great discoveries in geol-ogy, biology,pharmacology, and medicine.

Archimedes, Bernoulli, Descartes, Leonardo, Dürer, among others, were inspired by mol-luscs in their works, mainly studying the shell coils.

The origin of the fossils has always fascinated scholars of every period, and shells were at the center of important scientific and theological disputes like the problem of the Universal Deluge. So molluscs occupy an important place in the palaeontology too.

Thanks to Lamarck, they entered in the history of the biological sciences. Describing fossil shells, he firstly said that any variation of life forms is the result of an adaptation to envi-ronmental conditions and that living species are not immutable over time: a revolutionary theory reconsidered and revised by Darwin himself. Even in the physiology and biochemis-try, molluscs have always been an excellent biological model for evaluating hypotheses and perform experiments. Gastropods and squid have had a central position in several Noble Prize studies.

In the last decades, human activitiesdetermined a rise in atmospheric CO2which, in turn, promotes a slight, but significant acidification of both marine and freshwaters. The mol-luscs, builders of calcium carbonate shells, are very sensitive to the pH changes and are of-ten used as experimental models.

Mussels are very useful to assess the levels of contamination in coastal waters, due to their ability to focus, through bioaccumulation, chemicals with which they come into contact in their continuing filtration activity.

Finally, many molluscs have the capacity to produce biologically active substances which may affect the medicine. In this field, some important successes have been achieved.