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A seashell or sea shell, also known simply as a shell, is a hard, protective outer layer usually created by an animal or organism that lives in the sea. The shell is part of the body of the animal. Empty seashells are often found washed up on beaches by
beachcombers ''The Beachcombers'' is a Canadian comedy-drama television series that ran on CBC Television from October 1, 1972, to December 12, 1990. With over 350 episodes, it is one of the longest-running dramatic series ever made for English-language Canad ...
. The shells are empty because the animal has died and the soft parts have decomposed or been eaten by another animal. A seashell is usually the exoskeleton of an invertebrate (an animal without a backbone), and is typically composed of calcium carbonate or
chitin Chitin ( C8 H13 O5 N)n ( ) is a long-chain polymer of ''N''-acetylglucosamine, an amide derivative of glucose. Chitin is probably the second most abundant polysaccharide in nature (behind only cellulose); an estimated 1 billion tons of chit ...
. Most shells that are found on beaches are the shells of
marine Marine is an adjective meaning of or pertaining to the sea or ocean. Marine or marines may refer to: Ocean * Maritime (disambiguation) * Marine art * Marine biology * Marine debris * Marine habitats * Marine life * Marine pollution Military * ...
mollusks, partly because these shells are usually made of calcium carbonate, and endure better than shells made of chitin. Apart from mollusk shells, other shells that can be found on beaches are those of
barnacle A barnacle is a type of arthropod constituting the subclass Cirripedia in the subphylum Crustacea, and is hence related to crabs and lobsters. Barnacles are exclusively marine, and tend to live in shallow and tidal waters, typically in eros ...
s, horseshoe crabs and brachiopods. Marine
annelid The annelids (Annelida , from Latin ', "little ring"), also known as the segmented worms, are a large phylum, with over 22,000 extant species including ragworms, earthworms, and leeches. The species exist in and have adapted to various ecol ...
worms in the family Serpulidae create shells which are tubes made of calcium carbonate cemented onto other surfaces. The shells of
sea urchin Sea urchins () are spiny, globular echinoderms in the class Echinoidea. About 950 species of sea urchin live on the seabed of every ocean and inhabit every depth zone from the intertidal seashore down to . The spherical, hard shells (tests) of ...
s are called " tests", and the moulted shells of
crab Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (abdomen) ( el, βραχύς , translit=brachys = short, / = tail), usually hidden entirely under the thorax. They live in all the ...
s and
lobster Lobsters are a family (biology), family (Nephropidae, Synonym (taxonomy), synonym Homaridae) of marine crustaceans. They have long bodies with muscular tails and live in crevices or burrows on the sea floor. Three of their five pairs of legs ...
s are exuviae. While most seashells are external, some
cephalopods A cephalopod is any member of the molluscan class Cephalopoda (Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral body symmetry, a prominent head, an ...
have internal shells. Seashells have been used by humans for many different purposes throughout history and prehistory. However, seashells are not the only kind of shells; in various habitats, there are shells from freshwater animals such as freshwater mussels and
freshwater snail Freshwater snails are gastropod mollusks which live in fresh water. There are many different families. They are found throughout the world in various habitats, ranging from ephemeral pools to the largest lakes, and from small seeps and springs ...
s, and shells of
land snail A land snail is any of the numerous species of snail that live on land, as opposed to the sea snails and freshwater snails. ''Land snail'' is the common name for terrestrial gastropod mollusks that have shells (those without shells are known as ...
s.


Terminology

When the word "seashells" refers only to the shells of marine mollusks, then studying seashells is part of conchology. Conchologists or serious collectors who have a scientific bias are in general careful not to disturb living populations and habitats: even though they may collect a few live animals, most responsible collectors do not often over-collect or otherwise disturb ecosystems. The study of the entire molluscan animal (as well as the shell) is known as
malacology Malacology is the branch of invertebrate zoology that deals with the study of the Mollusca (mollusks or molluscs), the second-largest phylum of animals in terms of described species after the arthropods. Mollusks include snails and slugs, clams, ...
; a person who studies mollusks is known as a malacologist.


Occurrence

Seashells are commonly found in beach drift, which is natural detritus deposited along strandlines on beaches by the waves and the tides. Shells are very often washed up onto a beach empty and clean, the animal having already died. Empty seashells are often picked up by beachcombers. However, the majority of seashells which are offered for sale commercially have been collected alive (often in bulk) and then killed and cleaned, specifically for the commercial trade. This type of large-scale exploitation can sometimes have a strong negative impact on local ecosystems, and sometimes can significantly reduce the distribution of rare species.


Shell synthesis

Seashells are created by the
mollusc Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000  extant species of molluscs are recognized. The number of fossil species is esti ...
s that use them for protection. Molluscs have an outside layer of tissues on their bodies the
mantle A mantle is a piece of clothing, a type of cloak. Several other meanings are derived from that. Mantle may refer to: *Mantle (clothing), a cloak-like garment worn mainly by women as fashionable outerwear **Mantle (vesture), an Eastern Orthodox ve ...
which creates the shell material and which connects the shell to the mollusc. The specialized cells in the mantle form the shell using different minerals and proteins. The proteins are then used to create the framework that supports the growing shell. Calcium carbonate is the main compound of shell structure, aiding in adhesion.


Molluscan seashells

The word ''seashell'' is often used to mean only the shell of a
marine Marine is an adjective meaning of or pertaining to the sea or ocean. Marine or marines may refer to: Ocean * Maritime (disambiguation) * Marine art * Marine biology * Marine debris * Marine habitats * Marine life * Marine pollution Military * ...
mollusk. Marine mollusk shells that are familiar to beachcombers and thus most likely to be called "seashells" are the shells of marine species of
bivalves Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. As a group, bival ...
(or clams),
gastropod The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, from freshwater, and from land. T ...
s (or snails), scaphopods (or tusk shells), polyplacophorans (or
chiton Chitons () are marine molluscs of varying size in the class Polyplacophora (), formerly known as Amphineura. About 940 extant and 430 fossil species are recognized. They are also sometimes known as gumboots or sea cradles or coat-of-mail s ...
s), and
cephalopod A cephalopod is any member of the molluscan class Cephalopoda (Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral body symmetry, a prominent head ...
s (such as nautilus and spirula). These shells are very often the most commonly encountered, both in the wild, and for sale as decorative objects. Marine species of gastropods and bivalves are more numerous than land and freshwater species, and the shells are often larger and more robust. The shells of marine species also often have more sculpture and more color, although this is by no means always the case. In the tropical and sub-tropical areas of the planet, there are far more species of colorful, large, shallow water shelled marine mollusks than there are in the temperate zones and the regions closer to the poles. Although there are a number of species of shelled mollusks that are quite large, there are vast numbers of extremely small species too, see
micromollusk A micromollusk is a shelled mollusk which is extremely small, even at full adult size. The word is usually, but not exclusively, applied to marine mollusks, although in addition, numerous species of land snails and freshwater mollusks also ...
s. Not all mollusks are marine. There are numerous land and freshwater mollusks, see for example snail and
freshwater bivalves Freshwater bivalves are one kind of freshwater mollusc, along with freshwater snails. They are bivalves that live in fresh water as opposed to salt water, which is the main habitat type for bivalves. The majority of species of bivalve molluscs l ...
. In addition, not all mollusks have an external shell: some mollusks such as some cephalopods (squid and octopuses) have an internal shell, and many mollusks have no shell, see for example
slug Slug, or land slug, is a common name for any apparently shell-less terrestrial gastropod mollusc. The word ''slug'' is also often used as part of the common name of any gastropod mollusc that has no shell, a very reduced shell, or only a smal ...
and nudibranch.


Bivalves

Bivalves are often the most common seashells that wash up on large sandy beaches or in sheltered lagoons. They can sometimes be extremely numerous. Very often the two valves become separated. There are more than 15,000 species of bivalves that live in both marine and freshwater. Examples of bivalves are clams, scallops, mussels, and oysters. The majority of bivalves consist of two identical shells that are held together by a flexible hinge. The animal's body is held protectively inside these two shells. Bivalves that do not have two shells either have one shell or they lack a shell altogether. The shells are made of calcium carbonate and are formed in layers by secretions from the mantle. Bivalves, also known as pelecypods, are mostly filter feeders; through their gills, they draw in water, in which is trapped tiny food particles. Some bivalves have eyes and an open circulatory system. Bivalves are used all over the world as food and as a source of pearls. The larvae of some freshwater mussels can be dangerous to fish and can bore through wood.
Shell Beach, Western Australia Shell Beach is a beach in the Shark Bay region of Western Australia, located south-east of Denham. Situated on the northeastern side of the Taillefer Isthmus along the L'Haridon Bight, the beach is covered with shells for a stretch to a de ...
, is a beach which is entirely made up of the shells of the cockle '' Fragum erugatum''.


Gastropods

Certain species of gastropod seashells (the shells of
sea snail Sea snail is a common name for slow-moving marine gastropod molluscs, usually with visible external shells, such as whelk or abalone. They share the taxonomic class Gastropoda with slugs, which are distinguished from snails primarily by the ...
s) can sometimes be common, washed up on sandy beaches, and also on beaches that are surrounded by rocky marine habitat.


Polyplacophorans

Chiton Chitons () are marine molluscs of varying size in the class Polyplacophora (), formerly known as Amphineura. About 940 extant and 430 fossil species are recognized. They are also sometimes known as gumboots or sea cradles or coat-of-mail s ...
plates or valves often wash up on beaches in rocky areas where chitons are common. Chiton shells, which are composed of eight separate plates and a girdle, usually come apart not long after death, so they are almost always found as disarticulated plates. Plates from larger species of chitons are sometimes known as "butterfly shells" because of their shape.


Cephalopods

Only a few species of
cephalopod A cephalopod is any member of the molluscan class Cephalopoda (Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral body symmetry, a prominent head ...
s have shells (either internal or external) that are sometimes found washed up on beaches. Some cephalopods such as '' Sepia'', the cuttlefish, have a large internal shell, the
cuttlefish bone Cuttlebone, also known as cuttlefish bone, is a hard, brittle internal structure (an internal shell) found in all members of the family Sepiidae, commonly known as cuttlefish, within the cephalopods. In other cephalopod families it is calle ...
, and this often washes up on beaches in parts of the world where cuttlefish are common. '' Spirula spirula'' is a deep water squid-like cephalopod. It has an internal shell which is small (about 1 in or 24 mm) but very light and buoyant. This chambered shell floats very well and therefore washes up easily and is familiar to beachcombers in the tropics. '' Nautilus'' is the only genus of cephalopod that has a well-developed external shell. Females of the cephalopod genus '' Argonauta'' create a papery egg case which sometimes washes up on tropical beaches and is referred to as a "paper nautilus". The largest group of shelled cephalopods, the
ammonite Ammonoids are a group of extinct marine mollusc animals in the subclass Ammonoidea of the class Cephalopoda. These molluscs, commonly referred to as ammonites, are more closely related to living coleoids (i.e., octopuses, squid and cuttlefish) ...
s, are extinct, but their shells are very common in certain areas as fossils.


Molluscan seashells used by other animals

Empty molluscan seashells are a sturdy, and usually readily available, "free" resource which is often easily found on beaches, in the
intertidal zone The intertidal zone, also known as the foreshore, is the area above water level at low tide and underwater at high tide (in other words, the area within the tidal range). This area can include several types of habitats with various species o ...
, and in the shallow subtidal zone. As such they are sometimes used second-hand by animals other than humans for various purposes, including for protection (as in hermit crabs) and for construction.


Mollusks

* Carrier shells in the family Xenophoridae are marine shelled gastropods, fairly large sea snails. Most species of xenophorids cement a series of objects to the rim of their shells as they grow. These objects are sometimes small pebbles or other hard detritus. Very often shells of bivalves or smaller gastropods are used, depending on what is available on the particular
substrate Substrate may refer to: Physical layers *Substrate (biology), the natural environment in which an organism lives, or the surface or medium on which an organism grows or is attached ** Substrate (locomotion), the surface over which an organism lo ...
where the snail itself lives. It is not clear whether these shell attachments serve as camouflage, or whether they are intended to help prevent the shell sinking into a soft substrate. * Small
octopus An octopus ( : octopuses or octopodes, see below for variants) is a soft-bodied, eight- limbed mollusc of the order Octopoda (, ). The order consists of some 300 species and is grouped within the class Cephalopoda with squids, cuttle ...
es sometimes use an empty shell as a sort of cave to hide in, or hold seashells around themselves as a form of protection like a temporary fortress.


Invertebrates

* Almost all genera of hermit crabs use or "wear" empty marine gastropod shells throughout their lifespan, in order to protect their soft abdomens, and in order to have a strong shell to withdraw into if attacked by a predator. Each individual hermit crab is forced to find another gastropod shell on a regular basis, whenever it grows too large for the one it is currently using. :Some hermit crab species live on land and may be found quite some distance from the sea, including those in the tropical genus '' Coenobita''.


Conchology

There are numerous popular books and
field guide A field guide is a book designed to help the reader identify wildlife (flora or fauna) or other objects of natural occurrence (e.g. rocks and minerals). It is generally designed to be brought into the "field" or local area where such objects exi ...
s on the subject of shell-collecting. Although there are a number of books about land and freshwater mollusks, the majority of popular books emphasize, or focus exclusively on, the shells of marine mollusks. Both the science of studying mollusk shells and the hobby of collecting and classifying them are known as conchology. The line between professionals and amateur enthusiasts is often not well defined in this subject, because many amateurs have contributed to, and continue to contribute to, conchology and the larger science of
malacology Malacology is the branch of invertebrate zoology that deals with the study of the Mollusca (mollusks or molluscs), the second-largest phylum of animals in terms of described species after the arthropods. Mollusks include snails and slugs, clams, ...
. Many shell collectors belong to "shell clubs" where they can meet others who share their interests. A large number of amateurs collect the shells of marine mollusks, and this is partly because many shells wash up empty on beaches, or live in the intertidal or sub-tidal zones, and are therefore easily found and preserved without much in the way of specialized equipment or expensive supplies. Some shell collectors find their own material and keep careful records, or buy only "specimen shells", which means shells which have full collecting data: information including how, when, where, in what habitat, and by whom, the shells were collected. On the other hand, some collectors buy the more widely available commercially imported exotic shells, the majority of which have very little data, or none at all. To museum scientists, having full collecting data (when, where, and by whom it was collected) with a specimen is far more important than having the shell correctly identified. Some owners of shell collections hope to be able to donate their collection to a major natural history or zoology museum at some point, however, shells with little or no collecting data are usually of no value to science, and are likely not to be accepted by a major museum. Apart from any damage to the shell that may have happened ''before'' it was collected, shells can also suffer damage when they are stored or displayed. For an example of one rather serious kind of damage see
Byne's disease Byne's disease, more accurately known as Bynesian decay, is a peculiar and permanently damaging condition resulting from an ongoing chemical reaction which often attacks mollusk shells and other calcareous specimens that are in storage or on dis ...
.


Shell clubs

There are a number of clubs or societies which consist of people who are united by a shared interest in shells. In the US, these clubs are more common in southerly coastal areas, such as Florida and California, where the marine fauna is rich in species.


Identification

Seashells are usually identified by consulting general or regional shell-collecting
field guide A field guide is a book designed to help the reader identify wildlife (flora or fauna) or other objects of natural occurrence (e.g. rocks and minerals). It is generally designed to be brought into the "field" or local area where such objects exi ...
s, and specific scientific books on different taxa of shell-bearing mollusks (
monograph A monograph is a specialist work of writing (in contrast to reference works) or exhibition on a single subject or an aspect of a subject, often by a single author or artist, and usually on a scholarly subject. In library cataloging, ''monograph ...
s) or "iconographies" (limited text – mainly photographs or other illustrations). (For a few titles on this subject in the US, see the list of books at the foot of this article.) Identifications to the species level are generally achieved by examining illustrations and written descriptions, rather than by the use of Identification keys, as is often the case in identifying plants and other phyla of invertebrates. The construction of functional keys for the identification of the shells of marine mollusks to the species level can be very difficult, because of the great variability within many species and families. The identification of certain individual species is often very difficult, even for a specialist in that particular family. Some species cannot be differentiated on the basis of shell character alone. Numerous smaller and more obscure mollusk species (see
micromollusk A micromollusk is a shelled mollusk which is extremely small, even at full adult size. The word is usually, but not exclusively, applied to marine mollusks, although in addition, numerous species of land snails and freshwater mollusks also ...
) are yet to be discovered and named. In other words, they have not yet been differentiated from similar species and assigned scientific (binomial) names in articles in journals recognized by the
International Commission on Zoological Nomenclature The International Commission on Zoological Nomenclature (ICZN) is an organization dedicated to "achieving stability and sense in the scientific naming of animals". Founded in 1895, it currently comprises 26 commissioners from 20 countries. Orga ...
(ICZN). Large numbers of new species are published in the scientific literature each year. There are currently an estimated 100,000 species of mollusks worldwide.


Non-marine "seashells"

The term ''seashell'' is also applied loosely to mollusk shells that are not of marine origin, for example by people walking the shores of lakes and rivers using the term for the freshwater mollusk shells they encounter. Seashells purchased from tourist shops or dealers may include various freshwater and terrestrial shells as well. Non-marine items offered may include large and colorful tropical
land snail A land snail is any of the numerous species of snail that live on land, as opposed to the sea snails and freshwater snails. ''Land snail'' is the common name for terrestrial gastropod mollusks that have shells (those without shells are known as ...
shells, freshwater
apple snail Ampullariidae, commonly known as the apple snails, is a family of large freshwater snails, aquatic gastropod mollusks with a gill and an operculum. These snails simultaneously have a gill and a lung as functional respiratory structures, which ...
shells, and pearly freshwater
unionid mussel The Unionidae are a family of freshwater mussels, the largest in the order Unionida, the bivalve molluscs sometimes known as river mussels, or simply as unionids. The range of distribution for this family is world-wide. It is at its most divers ...
shells. This can be confusing to collectors, as non-marine shells are often not included in their reference books.


Cultural significance


Currency

Seashells have been used as a medium of exchange in various places, including many Indian Ocean and Pacific Ocean islands, also in North America, Africa and the Caribbean. * The most common species of shells to be used as currency have been '' Monetaria moneta'', the "money cowry", and certain
dentalium Dentalium may refer to: * ''Dentalium'' (genus), a genus of tooth shells * Dentalium (anthropology) The word dentalium, as commonly used by Native American artists and anthropologists, refers to tooth shells or tusk shells used in indigenous jew ...
tusk shells, used in North Western North America for many centuries. * Many of the tribes and nations all across the continent of Africa have historically used th
cowry
as their media of exchange. The cowry circulated, historically, alongside metal coins and goods, and foreign currencies. Being durable and easy to carry the cowry made a very favorable currency. * Some tribes of the indigenous peoples of the Americas used shells for wampum and
hair pipe A Hair pipe is a term for an elongated bead, more than 1.5 inches long, which are popular with American Indians, particularly from the Great Plains and Northwest Plateau. History In 1878, Joseph H. Sherburne became a trader to the Ponca peopl ...
s. The Native American '' wampum belts'' were made of the shell of the quahog clam.


Tools

Seashells have often been used as tools, because of their strength and the variety of their shapes. * Giant clams (Family Tridacnidae) have been used as bowls, and when big enough, even as bathtubs and baptismal fonts. * ''
Melo melo ''Melo melo'', common name the Indian volute or bailer shell, is a very large edible sea snail, a marine gastropod mollusc in the family Volutidae, the volutes. Distribution The distribution of this species is restricted to Southeast Asia ...
'', the "bailer volute", is so named because Native Australians used it to
bail out A bailout is the provision of financial help to a corporation or country which otherwise would be on the brink of bankruptcy. A bailout differs from the term ''bail-in'' (coined in 2010) under which the bondholders or depositors of global sy ...
their canoes. * Many different species of bivalves have been used as scrapers, blades, clasps, and other such tools, due to their shape. * Some marine gastropods have been used for oil lamps, the oil being poured in the aperture of the shell, and the
siphonal canal The siphonal canal is an anatomical feature of the shells of certain groups of sea snails within the clade Neogastropoda. Some sea marine gastropods have a soft tubular anterior extension of the mantle called a siphon through which water is ...
serving as a holder for the wick.


Horticulture

Because seashells are in some areas a readily available bulk source of calcium carbonate, shells such as oyster shells are sometimes used as soil conditioners in horticulture. The shells are broken or ground into small pieces in order to have the desired effect of raising the pH and increasing the calcium content in the soil.


Religion and spirituality

Seashells have played a part in religion and spirituality, sometimes even as ritual objects. * In Christianity, the
scallop Scallop () is a common name that encompasses various species of marine bivalve mollusks in the taxonomic family Pectinidae, the scallops. However, the common name "scallop" is also sometimes applied to species in other closely related families ...
shell is considered to be the symbol of Saint James the Great, see ''
Pecten jacobaeus ''Pecten jacobaeus'', the Mediterranean scallop, is a species of scallop, an edible saltwater scallop, a marine bivalve mollusc in the family Pectinidae, the scallops. Description ''Pecten jacobaeus'' usually reaches a length of about , but ...
''. * In Hinduism, left-handed shells of ''
Turbinella pyrum ''Turbinella pyrum'', common names the chank shell, sacred chank or chank, also known as the divine conch, sometimes referred to simply as a conch, is a species of very large sea snail with a gill and an operculum, a marine gastropod mollusk ...
'' (the sacred shankha) are considered to be sacred to the god Vishnu. The person who finds a left-handed chank shell (one that coils to the left) is sacred to Vishnu, as well. The chank shell also plays an important role in Buddhism. * Cowries have often been considered to be symbols of female fertility. They were often treated as actual fertility charms. The dorsum of the shell resembles a pregnant belly, and the underside of the shell resembles a vulva. In the South Indian state of Kerala, cowries are used for making astrological predictions. * In the
Santería Santería (), also known as Regla de Ocha, Regla Lucumí, or Lucumí, is an African diaspora religions, African diasporic religion that developed in Cuba during the late 19th century. It arose through a process of syncretism between the tradit ...
religion, shells are used for
divination Divination (from Latin ''divinare'', 'to foresee, to foretell, to predict, to prophesy') is the attempt to gain insight into a question or situation by way of an occultic, standardized process or ritual. Used in various forms throughout histor ...
. * The Moche culture of ancient Peru worshipped animals and the sea, and often depicted shells in their art. * In Christianity, the top of the sand dollar represents the Star of Bethlehem that led the Wise Men to the manger of Christ. Outside the "star" you will see the Easter Lily, a sign of Jesus' Resurrection. There are four holes that represent the holes in the Lord's hands and feet. The center hole is the Wound to His Sacred Heart by the spear of Longinus. On the other side of the sand dollar, you will see Poinsettia. Lastly, if you break open the sand dollar, five doves will come out, the doves of Peace and Joy.


Musical instruments

Seashells have been used as musical instruments,
wind instruments A wind instrument is a musical instrument that contains some type of resonator (usually a tube) in which a column of air is set into vibration by the player blowing into (or over) a mouthpiece set at or near the end of the resonator. The pitc ...
for many hundreds if not thousands of years. Most often the shells of large sea snails are used, as trumpets, by cutting a hole in the spire of the shell or cutting off the tip of the spire altogether. Various different kinds of large marine gastropod shells can be turned into "blowing shells", however the most commonly encountered species used as "
conch Conch () is a common name of a number of different medium-to-large-sized sea snails. Conch shells typically have a high spire and a noticeable siphonal canal (in other words, the shell comes to a noticeable point at both ends). In North Am ...
" trumpets are: * The sacred chank, ''
Turbinella pyrum ''Turbinella pyrum'', common names the chank shell, sacred chank or chank, also known as the divine conch, sometimes referred to simply as a conch, is a species of very large sea snail with a gill and an operculum, a marine gastropod mollusk ...
'', known in India as the shankha. In Tibet it is known as "dung-dkar". * The Triton shell also known as "Triton's trumpet" '' Charonia tritonis'' which is used as a trumpet in Melanesian and Polynesian culture and also in Korea and Japan. In Japan this kind of trumpet is known as the
horagai ''Horagai'' () (or ''jinkai'' ) are large conch shells, usually from ''Charonia tritonis'', that have been used as trumpets in Japan for many centuries. The instrument, which has served a number of purposes throughout Japanese history, has been ...
. In Korea it is known as the nagak. In some Polynesian islands it is known as "''pu''". * The
Queen Conch ''Aliger gigas,'' originally known as ''Strombus gigas'' or more recently as ''Lobatus gigas'', commonly known as the queen conch, is a species of large sea snail, a marine gastropod mollusc in the family of true conches, the Strombidae. Th ...
''
Lobatus gigas ''Aliger gigas,'' originally known as ''Strombus gigas'' or more recently as ''Lobatus gigas'', common name, commonly known as the queen conch, is a species of large sea snail, a marine gastropod mollusc in the family (biology), family of true c ...
'', has been used as a trumpet in the Caribbean. Children in some cultures are often told the myth that you can hear the sound of the ocean by holding a seashell to ones ear. This is due to the effect of seashell resonance.


Personal adornment

Whole seashells or parts of sea shells have been used as jewelry or in other forms of adornment since prehistoric times. Mother of pearl was historically primarily a seashell product, although more recently some mother of pearl comes from freshwater mussels. Also see pearl. * Shell necklaces have been found in Stone Age graves as far inland as the Dordogne Valley in France. * Seashells are often used whole and drilled, so that they can be threaded like beads, or cut into pieces of various shapes. Sometimes shells can be found that are already "drilled" by predatory snails of the family Naticidae. Fine whole shell necklaces were made by Tasmanian Aboriginal women for more than 2,600 years. The necklaces represent a significant cultural tradition which is still practised by Palawa women elders. The shells used include pearly green and blue-green maireener (rainbow kelp) shells, brown and white rice shells, black cats' teeth shells and pink button shells. * Naturally-occurring, beachworn, cone shell "tops" (the broken-off spire of the shell, which often has a hole worn at the tip) can function as beads without any further modification. In Hawaii these natural beads were traditionally collected from the beach drift in order to make puka shell jewelry. Since it is hard to obtain large quantities of naturally-occurring beachworn cone tops, almost all modern puka shell jewelry uses cheaper imitations, cut from thin shells of other species of mollusk, or even made of plastic. * Shells historically have been and still are made into, or incorporated into, necklaces, pendants, beads, earrings, buttons, brooches, rings, hair combs, belt buckles and other uses. * The shell of the large "bullmouth helmet" sea snail, scientific name ''
Cypraecassis rufa ''Cypraecassis rufa'' is a species of large sea snail, a marine gastropod mollusc in the family Cassidae. It is commonly known as the bullmouth shell or red helmet shell, and also as the cameo shell. Distribution This species is found of ...
'', was historically, and still is, used to make valuable cameos. * Mother of pearl from many seashells including species in the family Trochidae, Turbinidae, Haliotidae, and various pearly bivalves, has often been used in jewelry, buttons, etc. * In London, Pearly Kings and Queens traditionally wear clothing covered in patterns made up of hundreds of "pearl buttons", in other words, buttons made of mother-of-pearl or
nacre Nacre ( , ), also known as mother of pearl, is an organicinorganic composite material produced by some molluscs as an inner shell layer; it is also the material of which pearls are composed. It is strong, resilient, and iridescent. Nacre is f ...
. In recent years however, the majority of "pearl buttons" are imitations that are made of pearlescent plastic.


Creating Crafts

"
Sailor's Valentines A sailor's valentine is a form of shellcraft, a type of mostly antique souvenir, or sentimental gift made using large numbers of small seashells. These were originally made between 1830 and 1890, and they were designed to be brought home from a ...
" were late 19th-century decorative keepsakes which were made from the Caribbean, and which were often purchased by sailors to give to their loved ones back home for example in England. These valentines consisted of elaborate arrangements of small seashells glued into attractive symmetrical designs, which were encased on a wooden (usually octagonal) hinged box-frame. The patterns used often featured heart-shaped designs, or included a sentimental expression of love spelled out in small shells. The making of shell work artifacts is a practice of Aboriginal women from La Perouse in
Sydney Sydney ( ) is the capital city of the state of New South Wales, and the most populous city in both Australia and Oceania. Located on Australia's east coast, the metropolis surrounds Sydney Harbour and extends about towards the Blue Mountain ...
, dating back to the 19th century. Shell work objects include baby shoes, jewelry boxes and replicas of famous landmarks, including the Sydney Harbour Bridge and the
Sydney Opera House The Sydney Opera House is a multi-venue performing arts centre in Sydney. Located on the foreshore of Sydney Harbour, it is widely regarded as one of the world's most famous and distinctive buildings and a masterpiece of 20th-century architec ...
. The shellwork tradition began as an Aboriginal women's craft which was adapted and tailored to suit the tourist souvenir market, and which is now considered high art.


Architectural decoration

Small pieces of colored and iridescent shell have been used to create mosaics and inlays, which have been used to decorate walls, furniture and boxes. Large numbers of whole seashells, arranged to form patterns, have been used to decorate mirror frames, furniture and man-made
shell grotto A shell grotto is a type of folly, a grotto decorated with sea shells. The shell grotto was a popular feature of many British country houses in the 17th and 18th centuries. It suited the Baroque and Rococo styles (which used swirling motifs sim ...
s.


Art

A very large outdoor sculpture at
Akkulam Aakkulam is a region in Trivandrum city, the capital of Kerala state in India. It is about 10 km from Thiruvananthapuram city center. situated where the Akkulam Lake joins the sea. Akkulam Tourist village and Akkulam Boat Club are the ma ...
of a gastropod seashell is a reference to the sacred chank shell ''
Turbinella pyrum ''Turbinella pyrum'', common names the chank shell, sacred chank or chank, also known as the divine conch, sometimes referred to simply as a conch, is a species of very large sea snail with a gill and an operculum, a marine gastropod mollusk ...
'' of India. In 2003, Maggi Hambling designed a striking 13 ft (4 m) high sculpture of a
scallop Scallop () is a common name that encompasses various species of marine bivalve mollusks in the taxonomic family Pectinidae, the scallops. However, the common name "scallop" is also sometimes applied to species in other closely related families ...
shell which stands on the beach at Aldeburgh, in England. The goddess of love, Venus or Aphrodite, is often traditionally depicted rising from the sea on a seashell. In '' The Birth of Venus'',
Botticelli Alessandro di Mariano di Vanni Filipepi ( – May 17, 1510), known as Sandro Botticelli (, ), was an Italian painter of the Early Renaissance. Botticelli's posthumous reputation suffered until the late 19th century, when he was rediscovered ...
depicted the goddess Venus rising from the ocean on a
scallop Scallop () is a common name that encompasses various species of marine bivalve mollusks in the taxonomic family Pectinidae, the scallops. However, the common name "scallop" is also sometimes applied to species in other closely related families ...
shell.


Poultry feeds

Sea shells found in the creek and backwater of the coast of west India are used as an additive to poultry feed. They are crushed and mixed with jowar maize and dry fish.


Use

Seashells, namely from bivalves and gastropods, are fundamentally composed of calcium carbonate. In this sense, they have potential to be used as raw material in the production of lime. Along the
Gulf Coast of the United States The Gulf Coast of the United States, also known as the Gulf South, is the coastline along the Southern United States where they meet the Gulf of Mexico. The coastal states that have a shoreline on the Gulf of Mexico are Texas, Louisiana, Mississ ...
, oyster shells were mixed into cement to make "shellcrete" which could form bricks, blocks and platforms. It could also be applied over logs. A notable example is the 19th-century
Sabine Pass Lighthouse The Sabine Pass Lighthouse, or Sabine Pass Light as it was referred to by the United States Coast Guard, is a historic lighthouse, as part of a gulf coast light station, on the Louisiana side of the Sabine River, in Cameron Parish, across fro ...
in Louisiana, near Texas.


Shells of other marine invertebrates


Arthropods

Many arthropods have sclerites, or hardened body parts, which form a stiff exoskeleton made up mostly of
chitin Chitin ( C8 H13 O5 N)n ( ) is a long-chain polymer of ''N''-acetylglucosamine, an amide derivative of glucose. Chitin is probably the second most abundant polysaccharide in nature (behind only cellulose); an estimated 1 billion tons of chit ...
. In crustaceans, especially those of the class Malacostraca (crabs, shrimps and lobsters, for instance), the plates of the exoskeleton may be fused to form a more or less rigid
carapace A carapace is a Dorsum (biology), dorsal (upper) section of the exoskeleton or shell in a number of animal groups, including arthropods, such as crustaceans and arachnids, as well as vertebrates, such as turtles and tortoises. In turtles and tor ...
. Moulted carapaces of a variety of marine malacostraceans often wash up on beaches. The horseshoe crab is an arthropod of the family Limulidae. The shells or exuviae of these arachnid relatives are common in beach drift in certain areas of the world.


Echinoderms

Some echinoderms such as
sea urchin Sea urchins () are spiny, globular echinoderms in the class Echinoidea. About 950 species of sea urchin live on the seabed of every ocean and inhabit every depth zone from the intertidal seashore down to . The spherical, hard shells (tests) of ...
s, including
heart urchin The heart urchins or Spatangoida are an order of sea urchins. Their body is a somewhat elongated oval in form, and is distinguished by the mouth being placed towards one end of the animal, and the anus towards the other. As a result, heart urch ...
s and sand dollars, have a hard "test" or shell. After the animal dies, the flesh rots out and the spines fall off, and then fairly often the empty test washes up whole onto a beach, where it can be found by a beachcomber. These tests are fragile and easily broken into pieces.


Brachiopods

The brachiopods, or lamp shells, superficially resemble clams, but the phylum is not closely related to mollusks. Most lines of brachiopods ended during the Permian-Triassic extinction event, and their ecological niche was filled by bivalves. A few of the remaining species of brachiopods occur in the low
intertidal zone The intertidal zone, also known as the foreshore, is the area above water level at low tide and underwater at high tide (in other words, the area within the tidal range). This area can include several types of habitats with various species o ...
and thus can be found live by beachcombers.


Annelids

Some polychaetes, marine annelid worms in the family Serpulidae, secrete a hard tube made of calcium carbonate, adhering to stones or other shells. This tube resembles, and can be confused with, the shell of marine gastropod mollusks in the family Vermetidae, the worm snails.


Other more atypical kinds

A few other categories of marine animals leave remains which might be considered "seashells" in the widest possible sense of the word.


Chelonians

Sea turtles have a
carapace A carapace is a Dorsum (biology), dorsal (upper) section of the exoskeleton or shell in a number of animal groups, including arthropods, such as crustaceans and arachnids, as well as vertebrates, such as turtles and tortoises. In turtles and tor ...
and plastron of bone and
cartilage Cartilage is a resilient and smooth type of connective tissue. In tetrapods, it covers and protects the ends of long bones at the joints as articular cartilage, and is a structural component of many body parts including the rib cage, the neck an ...
which is developed from their
rib In vertebrate anatomy, ribs ( la, costae) are the long curved bones which form the rib cage, part of the axial skeleton. In most tetrapods, ribs surround the chest, enabling the lungs to expand and thus facilitate breathing by expanding the ches ...
s. Infrequently a turtle "shell" will wash up on a beach.


Hard corals

Pieces of the hard skeleton of corals commonly wash up on beaches in areas where corals grow. The construction of the shell-like structures of corals are aided by a
symbiotic Symbiosis (from Greek , , "living together", from , , "together", and , bíōsis, "living") is any type of a close and long-term biological interaction between two different biological organisms, be it mutualistic, commensalistic, or parasit ...
relationship with a class of
algae Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular mic ...
, zooxanthellae. Typically a coral polyp will harbor particular species of algae, which will photosynthesise and thereby provide energy for the coral and aid in calcification, while living in a safe environment and using the carbon dioxide and nitrogenous waste produced by the polyp. Coral bleaching is a disruption of the balance between polyps and algae, and can lead to the breakdown and death of coral reefs.


Soft corals

The skeletons of soft corals such as gorgonians, also known as sea fans and
sea whip Alcyonacea, or soft corals, are an order of corals. In addition to the fleshy soft corals, the order Alcyonacea now contains all species previously known as "gorgonian corals", that produce a more or less hard skeleton, though quite different f ...
s, commonly wash ashore in the tropics after storms.


Plankton and protists

Plant-like
diatom A diatom (Neo-Latin ''diatoma''), "a cutting through, a severance", from el, διάτομος, diátomos, "cut in half, divided equally" from el, διατέμνω, diatémno, "to cut in twain". is any member of a large group comprising sev ...
s and animal-like radiolarians are two forms of plankton which form hard silicate shells. Foraminifera and coccolithophores create shells known as "
tests Test(s), testing, or TEST may refer to: * Test (assessment), an educational assessment intended to measure the respondents' knowledge or other abilities Arts and entertainment * ''Test'' (2013 film), an American film * ''Test'' (2014 film), ...
" which are made of calcium carbonate. These shells and tests are usually microscopic in size, though in the case of foraminifera, they are sometimes visible to the naked eye, often resembling miniature mollusk shells.


See also

*
Bailey-Matthews Shell Museum The Bailey-Matthews National Shell Museum is a museum devoted to every aspect of seashells, conchology, and malacology, including the paleontological and archeological/anthropological aspects of the study of shells. The museum is located in the ...
*
Marine biogenic calcification Marine biogenic calcification is the process by which marine organisms such as oysters and clams form calcium carbonate. Seawater is full of dissolved compounds, ions and nutrients that organisms can use for energy and, in the case of calcificatio ...
* Mollusk shell * Ocean acidification * Seashell resonance *
Seashell surface In mathematics, a seashell surface is a surface made by a circle which spirals up the ''z''-axis while decreasing its own radius and distance from the ''z''-axis. Not all seashell surfaces describe actual seashells found in nature. Parametriza ...
, a mathematical construct *
Shell growth in estuaries Shell growth in estuaries is an aspect of marine biology that has attracted a number of scientific research studies. Many groups of marine organisms produce calcified exoskeletons, commonly known as seashell, shells, hard calcium carbonate struct ...
*
Shell purse A shell purse is a type of coin purse that is made from whole or trimmed mollusk shells, especially from bivalve mollusc shells. These purses are of mainly novelty use and purchased as souvenirs of visits, etc. In the past, some were engraved or p ...
* Small shelly fauna


References


Citations


Sources

; Books * Abbott R. Tucker & S. Peter Dance, 1982, ''Compendium of Seashells, A full color guide to more than 4,200 of the World's Marine shells'', E.P. Dutton, Inc, New York, . * Abbott R. Tucker, 1985, ''Seashells of the World: a guide to the better-known species'', 1985, Golden Press, New York, . * Abbott, R. Tucker, 1986, ''Seashells of North America'', St. Martin's Press, New York, . * Abbott, R. Tucker, 1974, ''American Seashells'', Second edition, Van Nostrand Rheinhold, New York, .


External links

{{wikiquote
Hohlman Shell Collection, Florida Institute of Technology
Zoology Mollusc shells Mollusc products Collecting