To admire a seashell is to unconsciously pay homage to the mollusk that created it. These animals, the epitome of softness and slowness, are in reality formidable builders, capable of an architectural prowess probably unsurpassed in the animal kingdom. Number of species known 125.000 exceeds species, each acutely distinct from each other, these creatures have not yet ceased to astonish us as they reveal their myriad wonders. It is enough to satisfy the curiosity of a collector for an entire lifetime.
Living species of mollusks worldwide have been classified under thousands of families, species. Mollusks have been evolving for more than 550 million years, an immense amount of time for speciation and divergence. Divergence can occur whenever a population (a group of organisms of one species) is split into two or more parts that have no chance to interbreed. This can happen as a result of chance dispersal to isolated islands or through geological changes, such as the uplift of the Isthmus of Panama, which separated the Western Atlantic and Eastern Pacific. Such divergences have created a rich profusion of mollusk species and, naturally, of shell kinds alongside.
Conchology (a branch of Zoologie) is the study of mollusks and sea shell.
Mollusk Anatomy
A seashell is the solid and usually inflexible outer covering of a soft-bodied, fleshy sea marine animal. It is to a mollusk what the skeleton is to a mammal. It supports and protects the unsupported and vulnerable soft body parts.
All mollusks share a common characteristic, a soft body. They also have a head, a muscular foot and a visceral mass that contains their organs. The visceral mass is covered by the mantle, a fold of skin. Overflowing from the visceral mass, the mantle forms a pocket: the palleal cavity. It is within this chamber that exchanges with the environment occur. Here is the location of the respiratory system (gills or lungs, according to the animal’s lifestyle), as well as the openings of the digestive, excretory and reproductory organs.
From Head to Foot
The mollusk’s head contains the mouth, as well as receptors sensitive to light, touch, spatial orientation, movement and chemical stimuli, but not to sound as we perceive it. The foot is muscular and contains many gaps that are capable of filling with blood. As its name implies, its main use is for locomotion. One unusual characteristic of mollusks is that their blood contains hemocyanin, a copper-containing protein used as a means to carry oxygen in the bloodstream, similar to the iron-rich hemoglobin in human blood. However, unlike human blood, which turns red when oxygenated, the chemically based pigments in hemocyanin cause a mollusk’s oxygenated blood to become blue.
The Magical Mantle
The mantle is undoubtedly the most mysterious and fascinating component of these animals since it is directly involved in secreting the shell. This workload is shared by the activity zone: the border of the mantle is assigned the task of enlarging the shell, where as the rest of the mantle’s surface is dedicated to the thickening of the shell. The mantle’s border is also charged with making a hard substance, named conchiolin (it is chemically similar to chitin, which forms the exoskeletons of insects and crustaceans). This substance forms a thin external film on the shell – the periostracum – a kind of protective varnish. Underneath, we find a thick calcareous layer whose crystals, in the form of prisms, are more or less perpendicular to the shell’s surface. Growing within this conchiolin matrix, these crystals enlarge the holes until a thin film remains between each one of them. In fact, this second layer, the ostracum, contains very little of the conchiolin and is made up of the very resistant composite material.
A final zone comes in direct contact with the mantle and is fabricated by its entire surface: It is the hypostracum. Here, the crystals are deposited in lamellae, parallel to the surface. Depending on the species, the crystals are composed of aragonite that they have the ability to produce the splendid iridescence found on the inside of shells known as nacre, of mother of pearl. Unfortunately, there are fewer shells with nacre than without.
The Shell
The shell may be thick or thin, opaque or translucent, colourful or colourless, smooth or
variously ornamented with spines, scales, ridges, furrows, pits, and other relief or incised features. Its overall shape is what makes it so obviously a shell and gives us our first clue to its identity.
The basic building material of a shell is calcium carbonate or chalk. With the addition of smaller amounts of other materials to harden it, the shell can grow and protect the mollusk throughout its life.
Sunlight and warmth are essential to the production of bright and varied colours and for the growth of thick and well-ornamented shells. Warm water shells are generally more colourful than those from cold water. Areas rich in coral provide the best living conditions for mollusks and other marine animals. They also produce the most colourful shells.
Shells have always been considered “artifices of nature”, and therefore a tangible reflection of the wonder and perfection of Creation. Shell collecting, a very popular pastime these days, is far from being new. Human societies that dominated North Africa and today’s Israel used seashells to make beads thousands years ago provide scientists with some of the earliest known evidence of modern human culture. Moreover, the “recreation of the eye and of the mind” inspired by these marine creatures is a concept that dates back to Cicero (106-43 BC). In “De Oratore”, Cicero exalted the value of the seashells cultivated by two friends who spent their hours of leisure collecting shells. It is possible that the ancient Romans made shell collections. Explorations of the ruins of Pompeii, buried by volcanic ash from the eruption of Vesuvius in 79 A.D., have revealed accumulations of shell of a variety of species. As more and more of the world’s oceans and islands were explored, the range of shells available to collectors increased and the prices charged for them fell, making them accessible to far more people than the few wealthy collectors of the early years.
Today’s shell collectors have the opportunity to study species from all around the world, but because of their sheer number they have the great responsibility to consider the conservation of the shells and their habitats. It should never be forgotten that a shell is the home of living creature. If the shell is picked up empty then clearly the once-living mollusk has finished with it, but if the shell still houses the organism which created it, the
collector should very carefully deliberate on the one who needs the shell the most. Is the need for an addition to the shell collection greater than the value of the mollusk’s life?
Throughout history, the seashell has served us in numerous ways.
Here are some examples:
Food
Discarded shells have been found in the waste-heaps of prehistoric settlements, but the Romans may have been one of the earliest peoples to farm mollusks, particularly oysters, as a food source.
Currency and Trade
The use of cowrie shells, as a form of currency was widespread in Asia, Central Africa, the Indian Ocean and the Malaysian Islands. Early traders made fortunes by carrying cowries from the Indian and Pacific oceans to West Africa, where they were exchanged for ivory, palm oil, and semi-precious stones.
Religion
The emblem of St. James is the scallop, and in times past pilgrims who visited his shrine at Santiago de Compostela would bring back a shell as proof of their pilgrimage. The conch shell is sacred to the Hindu god Vishnu.
Fashion and Jewellery
Shells have been used for adornment from the earliest times. Cowries, which were consecrated to Venus, were worn by Roman women and were often given as bridal gifts.
Art and Architecture
Shells are, and always have been, a great source of inspiration for artists. Of all shells, the scallop has perhaps been most frequently used-ornamenting Roman lead coffins, decorating niches and porticoes, carved above church doorways, chosen by Botticelli in his famous painting ‘The Birth Of Venus’ describing Venus.
Few living things can be preserved in a way that retains their natural beauty. For this reason, shells, which deteriorate little, are particularly attractive to artists and collectors.
Seashell Classification
People who have a common interest cannot converse about it efficiently unless they share a universal language regarding their interest. In order to produce a universal language, the most important aspects of the common interest need to be categorized and named. “Molluskan Nomenclature,” the universal classification for seashells, has been developing throughout history. The categorical hierarchy in ascending order is as follows:
Class
Superfamily
Family
Subfamily
Genus (specie)
Classification
Most authorities place living mollusks in 7 classes five of which are major classes:
1.Gastropod (the univalve snails. More than 105.000 known species)
2.Bivalvia (the clams(doublevalve clams. More than 20.000 known species)
3.Polyplacophor (the chitons More than 650 known species)
4.Scaphopoda (the tusk shells. More than 350 known species)
5. Aplacophora (More than 250 known species)
6.Monoplacophora
7.Cephalopoda (the squids)
Of these the Gastropod and the Bivalvia account for almost all of the living mollusks.
Gastropoda :
The 35 family representing majority of the Gastropoda are;
1.Architectonicidae (Sundials)
2.Bullidae (Bubble Shells)
3.Bursidae (Frog Shells)
4.Buccinidae (Whelks)
5.Cancellariidae (Nutmeg Shells)
6.Conidae (Cone Shells)
7.Conidae (Cone Shells)
8.Cypraeidae (Cowries)
9.Coralliophilidae (Latiaxis Shells)
10.Cassidae (False Tuns)
11.Epitoniidae (Wentletraps)
12.Eratoidae (False cowry)
13.Fasciolariidae (Horse Conchs and Tulip Shells)
14.Fissurellidae, Patellidae, Acmaeidae (Limpets)
15.Harpidae (Harp Shells and Morums)
16.Haliotidae (Abalones)
17.Janthinidae (Purple sea snails)
18.Littorinidae (Periwinkles)
19.Marginellidae (Margin Shells)
20.Mitridae and Costellariidae (Miter Shells)
21.Muricidae (Murexes)
22.Naticidae (Moon Snails)
23.Neritidae (Nerites)
24.Nautilidae (Chambered Nautilus)
25.Olividae (Olive Shells)
26.Ovulidae (Egg Shells)
27.Pleurotomariidae (Slit shells)*
28.Ranellidae (Tritons)
29.Strombidae (Conchs)
30.Turbinellidae (Vase Shells, Chank Shells and Pagoda Shells)
31.Terebridae (Auger Shells)
32.Turridae (Turrids)
33.Trochidae (Top Shells)
34.Turbinidae (Turban and Star Shells)
35.Volutidae (Volutes)
The major BIVALVIA families are as follows:
1.Carditidae (Cardita Clams)
2.Chamidae (Jewel Box Clams)
3.Cardiidae (Cockles)
4.Donacidae (Donax Clams)
5.Glycymerididae (Bittersweet Clams)
6.Pectinidae (Scallops)
7.Psammobiidae (Sunset Clams)
8.Spondylidae (Thorny Oyster)
9.Limidae (File Clam)
10.Lucinidae (Lucina Clams)
11.Tridacnidae (Fluted Giant Clam)
12.Tellinidae (Tellins)
13.Veneridae (Venus Clams)
Each seashell corresponds to a Latin name at each level of the hierarchy. There are roughly 400 known families. The genus of the seashell is generally regarded as the “name” of the shell. There are approximately 125.000 different names for seashells.
To complete the classification one has to identify:
The geographical site of discovery
the name of the discoverer
the date of discovery and
the size of the shell
As a rule class and family names are written in capital letters, subfamily and genus in small letters.
Classification and naming the shell is an important process which should be carefully followed.
During this process I acquired a library consisting of some hundred seashell books. Additionally research on the internet was essential.
I have attached pictures with identification cards of two seashells to exemplify the method of classification.
Gülsen, my wife and I have collected our first shell way back in 1961 along the Mediterranean coast at Karatas village near Adana, the same year we got married.
As part of my business I travelled many countries from Japan to Hawaii, from Europe to Argentina from U.S.A. to far east and very recently beginning 2011 our love far shells carried us to Zanzibar Island in Africa.
I thank my wife Gülsen for her lifetime support and encouragement, which brought this collection to this level.
I hope you will enjoy getting to know the collection as much as we have enjoyed collecting it, with patience and pleasure…
Hasan Güleşçi
Bodrum Maritime Museum
Bibliography:
1.Compendium of Seashells
by S.R. Tucker Abbott & Peter Dance.
Publisher: Odyssey - 2000
2.Encyclopedia of Marine Gastropods
by Alain Robin
Publisher: Die Deutsche Bibliothek - 2008
3.Shells
by Paul Starosta & Jacques Senders
Publisher: Tirefly Books Ltd. - 2007
4.Shells - Treasures of the Sea
by Leonard Hill
Publisher: Universe – 2000
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