Seashell
This articleneeds additional citations forverification.(January 2009) |
Part of a series on |
Seashells |
---|
![]() |
Mollusc shells |
About mollusc shells |
Other seashells |
![](https://upload.wikimedia.org/wikipedia/commons/thumb/8/86/Conchiglie_Seashells_01.jpg/220px-Conchiglie_Seashells_01.jpg)
![](https://upload.wikimedia.org/wikipedia/commons/thumb/8/8f/Selection_of_seashells.jpg/220px-Selection_of_seashells.jpg)
![](https://upload.wikimedia.org/wikipedia/commons/thumb/b/b3/Seashell_unknown_3.jpg/226px-Seashell_unknown_3.jpg)
![](https://upload.wikimedia.org/wikipedia/commons/thumb/f/f7/Different_types_of_shells.jpg/220px-Different_types_of_shells.jpg)
Aseashellorsea shell,also known simply as ashell,is a hard, protective outer layer usually created by ananimalor organism that lives in the sea. Most seashells are made bymollusks,such assnails,clams,andoystersto protect their soft insides.[1]Empty seashells are often found washed up onbeachesbybeachcombers.The shells are empty because the animal has died and the soft parts havedecomposedor been eaten by another organism.
A seashell is usually theexoskeletonof aninvertebrate(an animal without a backbone), and is typically composed ofcalcium carbonate[1]or chitin. Most shells that are found on beaches are the shells ofmarinemollusks, partly because these shells are usually made of calcium carbonate, and endure better than shells made of chitin.
Apart frommollusk shells,other shells that can be found on beaches are those ofbarnacles,horseshoe crabsandbrachiopods.Marineannelidworms in the familySerpulidaecreate shells which are tubes made of calcium carbonate cemented onto other surfaces. The shells ofsea urchinsare called "tests",and the moulted shells ofcrabsandlobstersareexuviae.While most seashells are external, somecephalopodshave 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 asfreshwater musselsandfreshwater snails,and shells ofland snails.
Terminology
[edit]When the word "seashells" refers only to the shells of marine mollusks, then studying seashells is part ofconchology.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 asmalacology;a person who studies mollusks is known as amalacologist.
Occurrence
[edit]Seashells are commonly found in beach drift, which is natural detritus deposited along strandlines onbeachesby thewavesand thetides.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.[2]This type of large-scale exploitation can sometimes have a strong negative impact on localecosystems,and sometimes can significantly reduce the distribution ofrare species.
Shell synthesis
[edit]Seashells are created by themolluscsthat use them for protection.[3]Molluscs have an outside layer of tissues on their bodies – themantle– which creates the shell material and which connects the shell to the mollusc. The specialized cells in the mantle form the shell using differentmineralsandproteins.[3]The proteins are then used to create the framework that supports the growing shell.Calcium carbonateis the main compound of shell structure, aiding inadhesion.[3]
Molluscan seashells
[edit]This sectionneeds additional citations forverification.(September 2011) |
![](https://upload.wikimedia.org/wikipedia/commons/thumb/1/1d/Seashells_North_Wales_1985.jpg/220px-Seashells_North_Wales_1985.jpg)
![](https://upload.wikimedia.org/wikipedia/commons/thumb/8/8a/Shells_on_the_seashore.jpg/220px-Shells_on_the_seashore.jpg)
The wordseashellis often used to mean only the shell of amarinemollusk.Marine mollusk shells that are familiar to beachcombers and thus most likely to be called "seashells" are the shells of marine species ofbivalves(orclams),gastropods(orsnails),scaphopods(ortusk shells),polyplacophorans(orchitons), andcephalopods(such asnautilusandspirula). 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 moresculptureand more color, although this is by no means always the case.
In thetropicaland 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, seemicromollusks.
Not all mollusks are marine. There are numerous land and freshwater mollusks, see for examplesnailandfreshwater bivalves.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 exampleslugandnudibranch.
Bivalves
[edit]![](https://upload.wikimedia.org/wikipedia/commons/thumb/e/e1/CoquillagesFadiouth.jpg/220px-CoquillagesFadiouth.jpg)
Bivalves are often the most common seashells that wash up on large sandy beaches or in shelteredlagoons.They can sometimes be extremely numerous. Very often the twovalvesbecome 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,is a beach which is entirely made up of the shells of thecockleFragum erugatum.
Gastropods
[edit]![](https://upload.wikimedia.org/wikipedia/commons/thumb/4/49/Sea_shells%2C_playa_grande%2C_costa_rica.jpg/220px-Sea_shells%2C_playa_grande%2C_costa_rica.jpg)
Certain species of gastropod seashells (the shells ofsea snails) can sometimes be common, washed up on sandy beaches, and also on beaches that are surrounded by rocky marine habitat.
Polyplacophorans
[edit]![](https://upload.wikimedia.org/wikipedia/commons/thumb/9/91/Chiton_tuberculatus_plates.jpg/130px-Chiton_tuberculatus_plates.jpg)
Chitonplates 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
[edit]![](https://upload.wikimedia.org/wikipedia/commons/thumb/3/38/Cuttlebone.jpg/130px-Cuttlebone.jpg)
![](https://upload.wikimedia.org/wikipedia/commons/thumb/9/94/Nautilus_species_shells.png/130px-Nautilus_species_shells.png)
Only a few species ofcephalopodshave shells (either internal or external) that are sometimes found washed up on beaches.
Some cephalopods such asSepia,the cuttlefish, have a large internal shell, thecuttlefish bone,and this often washes up on beaches in parts of the world where cuttlefish are common.
Spirula spirulais 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.
Nautilusis the only genus of cephalopod that has a well-developed external shell. Females of the cephalopod genusArgonautacreate 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, theammonites,are extinct, but their shells are very common in certain areas asfossils.
Molluscan seashells used by other animals
[edit]Empty molluscan seashells are a sturdy, and usually readily available, "free" resource which is often easily found on beaches, in theintertidal zone,and in the shallow subtidal zone. As such they are sometimes usedsecond-handby animals other than humans for various purposes, including for protection (as inhermit crabs) and for construction.
Mollusks
[edit]- Carrier shells in the familyXenophoridaeare 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 particularsubstratewhere the snail itself lives. It is not clear whether these shell attachments serve ascamouflage,or whether they are intended to help prevent the shell sinking into a soft substrate.
![](https://upload.wikimedia.org/wikipedia/commons/thumb/1/11/Ocellated_octopus.jpg/220px-Ocellated_octopus.jpg)
- Smalloctopusessometimes 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
[edit]![](https://upload.wikimedia.org/wikipedia/commons/thumb/4/40/Diogenes_pugilator.jpg/220px-Diogenes_pugilator.jpg)
Part of a series related to |
Biomineralization |
---|
![]() |
- Almost all genera ofhermit crabsuse 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 genusCoenobita.
Conchology
[edit]There are numerous popular books andfield guideson 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 asconchology.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 ofmalacology.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 theintertidalor 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 collectingdata: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. Tomuseumscientists, 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 happenedbeforeit was collected, shells can also suffer damage when they are stored or displayed. For an example of one rather serious kind of damage seeByne's disease.
Shell clubs
[edit]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 asFloridaandCalifornia,where the marine fauna is rich in species.
Identification
[edit]![](https://upload.wikimedia.org/wikipedia/commons/thumb/7/75/Concha_com_pintura_%281.2%29%2C_Acervo_do_Museu_do_Colono_%28Santa_Leopoldina%29.jpg/220px-Concha_com_pintura_%281.2%29%2C_Acervo_do_Museu_do_Colono_%28Santa_Leopoldina%29.jpg)
Seashells are usually identified by consulting general or regional shell-collectingfield guides,and specific scientific books on different taxa of shell-bearing mollusks (monographs) 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 ofIdentification 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 (seemicromollusk) 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 theInternational Commission on Zoological Nomenclature(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"
[edit]![](https://upload.wikimedia.org/wikipedia/commons/thumb/5/50/Shells01.jpg/220px-Shells01.jpg)
The termseashellis 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 thefreshwater molluskshells 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 tropicalland snailshells, freshwaterapple snailshells, and pearly freshwaterunionid musselshells. This can be confusing to collectors, as non-marine shells are often not included in their reference books.
Cultural significance
[edit]This sectionneeds additional citations forverification.(July 2016) |
Currency
[edit]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.
![](https://upload.wikimedia.org/wikipedia/commons/thumb/0/06/Cypraea-moneta-001.jpg/220px-Cypraea-moneta-001.jpg)
- The most common species of shells to be used as currency have beenMonetaria moneta,the "moneycowry",[4][5]and certaindentaliumtusk 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 thecowryas 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 theindigenous peoples of the Americasused shells forwampumandhair pipes.[6]The Native Americanwampumbeltswere made of the shell of thequahogclam.
Tools
[edit]Seashells have often been used astools,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 andbaptismalfonts.
- Melo melo,the "bailervolute",is so named because Native Australians used it tobail outtheir 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 foroil lamps,the oil being poured in the aperture of the shell, and thesiphonal canalserving as a holder for the wick.
Horticulture
[edit]Because seashells are in some areas a readily available bulk source of calcium carbonate, shells such asoystershells are sometimes used as soil conditioners inhorticulture.The shells are broken or ground into small pieces in order to have the desired effect of raising thepHand increasing thecalciumcontent in the soil.
Religion and spirituality
[edit]![](https://upload.wikimedia.org/wikipedia/commons/thumb/1/11/Flag_of_Kingdom_of_Travancore.svg/220px-Flag_of_Kingdom_of_Travancore.svg.png)
![](https://upload.wikimedia.org/wikipedia/commons/thumb/1/1e/Spatha_shell._From_Naqada_tomb_1539%2C_Egypt._Naqada_I_period._The_Petrie_Museum_of_Egyptian_Archaeology%2C_London.jpg/220px-Spatha_shell._From_Naqada_tomb_1539%2C_Egypt._Naqada_I_period._The_Petrie_Museum_of_Egyptian_Archaeology%2C_London.jpg)
Seashells have played a part in religion and spirituality, sometimes even as ritual objects.
- In Christianity, thescallopshell is considered to be the symbol ofSaint James the Great,seePecten jacobaeus.[7]
- InHinduism,left-handed shells ofTurbinella pyrum(the sacredshankha) are considered to be sacred to the godVishnu.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 inBuddhism.
- Cowrieshave often been considered to be symbols of female fertility. They were often treated as actual fertilitycharms.The dorsum of the shell resembles a pregnant belly, and the underside of the shell resembles avulva.In the South Indian state of Kerala, cowries are used for making astrological predictions.
- In theSanteríareligion, shells are used fordivination.
- TheMocheculture of ancientPeruworshipped animals and the sea, and often depicted shells in their art.[8]
- In Christianity, the top of thesand dollarrepresents 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.[9]
Musical instruments
[edit]![](https://upload.wikimedia.org/wikipedia/commons/thumb/8/83/Hindu_priest_blowing_conch_during_punja.jpg/220px-Hindu_priest_blowing_conch_during_punja.jpg)
![](https://upload.wikimedia.org/wikipedia/commons/thumb/a/a0/Gyeonbokgung-March-01.jpg/220px-Gyeonbokgung-March-01.jpg)
Seashells have been used as musical instruments,wind instrumentsfor many hundreds if not thousands of years. Most often the shells of large sea snails are used, as trumpets, by cutting a hole in thespireof 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"trumpets are:
- The sacred chank,Turbinella pyrum,known in India as theshankha.InTibetit is known as "dung-dkar".[10]
- TheTriton shellalso known as "Triton's trumpet"Charonia tritoniswhich is used as a trumpet in Melanesian and Polynesian culture and also inKoreaand Japan. In Japan this kind of trumpet is known as thehoragai.In Korea it is known as thenagak.In some Polynesian islands it is known as "pu".[10]
- TheQueen ConchLobatus gigas,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 ofseashell resonance.
Personal adornment
[edit]![](https://upload.wikimedia.org/wikipedia/commons/thumb/d/d8/Kikuyu_woman_traditional_dress.jpg/170px-Kikuyu_woman_traditional_dress.jpg)
![](https://upload.wikimedia.org/wikipedia/commons/thumb/0/0b/Pearlykingandqueen.jpg/170px-Pearlykingandqueen.jpg)
Whole seashells or parts of sea shells have been used as jewelry or in other forms of adornment since prehistoric times.Mother of pearlwas historically primarily a seashell product, although more recently some mother of pearl comes from freshwater mussels. Also seepearl.
- Shell necklaces have been found in Stone Age graves as far inland as theDordogneValley in France.
- Seashells are often used whole and drilled, so that they can be threaded likebeads,or cut into pieces of various shapes. Sometimes shells can be found that are already "drilled" by predatory snails of the familyNaticidae.Fine whole shell necklaces were made byTasmanian Aboriginalwomen for more than 2,600 years. The necklaces represent a significant cultural tradition which is still practised byPalawawomen 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.[11]
- 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. InHawaiithese natural beads were traditionally collected from the beach drift in order to makepuka shelljewelry. Since it is hard to obtain large quantities of naturally-occurring beachworn cone tops, almost all modern pukashell jewelryuses 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 nameCypraecassis rufa,was historically, and still is, used to make valuablecameos.
- Mother of pearlfrom many seashells including species in the familyTrochidae,Turbinidae,Haliotidae,and various pearly bivalves, has often been used in jewelry, buttons, etc.
- In London,Pearly Kings and Queenstraditionally wear clothing covered in patterns made up of hundreds of "pearlbuttons",in other words, buttons made ofmother-of-pearlornacre.In recent years however, the majority of "pearl buttons" are imitations that are made of pearlescent plastic.
Creating Crafts
[edit]"Sailor's Valentines"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 ofAboriginal womenfromLa PerouseinSydney,dating back to the 19th century. Shell work objects include baby shoes, jewelry boxes and replicas of famous landmarks, including theSydney Harbour Bridgeand theSydney Opera House.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.[12]
Architectural decoration
[edit]Small pieces of colored and iridescent shell have been used to createmosaicsandinlays,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 human-madeshell grottos.
Art
[edit]![](https://upload.wikimedia.org/wikipedia/commons/thumb/2/25/Aphrodite_Anadyomene_Louvre_CA2288.jpg/170px-Aphrodite_Anadyomene_Louvre_CA2288.jpg)
A very large outdoor sculpture atAkkulamof a gastropod seashell is a reference to the sacred chank shellTurbinella pyrumof India. In 2003,Maggi Hamblingdesigned a striking 13 ft (4 m) high sculpture of ascallopshell which stands on the beach atAldeburgh,in England. The goddess of love,VenusorAphrodite,is often traditionally depicted rising from the sea on a seashell. InThe Birth of Venus,Botticellidepicted the goddessVenusrising from the ocean on ascallopshell.
-
Enormous seashell sculpture atAkkulam,Thiruvananthapuram,India
-
Illustration from an 18th-century book, edited byAlbertus Seba.These decorative arrangements were a popular way to display seashells at the time
-
Portrait of the Shell Collector Jan Govertsen van der Aer, byHendrick Goltzius(1603)
Poultry feeds
[edit]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.[citation needed]
Use
[edit]Seashells, namely from bivalves[13]and gastropods, are fundamentally composed of calcium carbonate. In this sense, they have potential to be used as raw material in the production oflime.
Along theGulf Coast of the United States,oystershells were mixed intocementto make "shellcrete" which could form bricks, blocks and platforms. It could also be applied over logs.[14]A notable example is the 19th-centurySabine Pass Lighthousein Louisiana, near Texas.[15]
Shells of other marine invertebrates
[edit]Arthropods
[edit]![](https://upload.wikimedia.org/wikipedia/commons/thumb/e/e8/Crab_from_Long_Island.jpg/220px-Crab_from_Long_Island.jpg)
![](https://upload.wikimedia.org/wikipedia/commons/thumb/4/44/Horseshoe_Crab_remains.jpg/220px-Horseshoe_Crab_remains.jpg)
Manyarthropodshavesclerites,or hardened body parts, which form a stiff exoskeleton made up mostly ofchitin.Incrustaceans,especially those of the classMalacostraca(crabs, shrimps and lobsters, for instance), the plates of the exoskeleton may be fused to form a more or less rigidcarapace.Moulted carapaces of a variety of marine malacostraceans often wash up on beaches. Thehorseshoe crabis an arthropod of the familyLimulidae.The shells orexuviaeof these arachnid relatives are common in beach drift in certain areas of the world.
Echinoderms
[edit]![](https://upload.wikimedia.org/wikipedia/commons/thumb/f/f1/Sea_Urchin_test_5629_03_22.jpg/220px-Sea_Urchin_test_5629_03_22.jpg)
Someechinodermssuch assea urchins,includingheart urchinsandsand 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
[edit]Thebrachiopods,or lamp shells, superficially resemble clams, but the phylum is not closely related to mollusks. Most lines of brachiopods ended during thePermian-Triassic extinction event,and their ecological niche was filled by bivalves. A few of the remaining species of brachiopods occur in the lowintertidal zoneand thus can be found live by beachcombers.
Annelids
[edit]Somepolychaetes,marine annelid worms in the familySerpulidae,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 familyVermetidae,the worm snails.
Atypical shells
[edit]A few other categories of marine animals leave remains which might be considered "seashells" in the widest possible sense of the word.
Chelonians
[edit]Sea turtleshave acarapaceandplastronof bone andcartilagewhich is developed from theirribs.Infrequently a turtle "shell" will wash up on a beach.
Hard corals
[edit]Pieces of the hard skeleton ofcoralscommonly wash up on beaches in areas where corals grow.
The construction of the shell-like structures of corals are aided by asymbioticrelationship with a class ofalgae,zooxanthellae.Typically a coral polyp will harbor particular species of algae, which willphotosynthesiseand thereby provide energy for the coral and aid in calcification,[16]while living in a safe environment and using the carbon dioxide and nitrogenous waste produced by the polyp.Coral bleachingis a disruption of the balance between polyps and algae, and can lead to the breakdown and death of coral reefs.
Soft corals
[edit]![](https://upload.wikimedia.org/wikipedia/commons/thumb/8/8c/1-Gorgone.jpg/220px-1-Gorgone.jpg)
The skeletons of soft corals such asgorgonians,also known assea fansandsea whips,commonly wash ashore in thetropicsafter storms.
Plankton and protists
[edit]![](https://upload.wikimedia.org/wikipedia/commons/thumb/3/31/Diatoms_through_the_microscope.jpg/220px-Diatoms_through_the_microscope.jpg)
Plant-likediatomsand animal-likeradiolariansare two forms ofplanktonwhich form hardsilicateshells.Foraminiferaandcoccolithophorescreate shells known as "tests"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
[edit]- Bailey-Matthews Shell Museum
- Marine biogenic calcification
- Mollusk shell
- Ocean acidification
- Seashell resonance
- Seashell surface,a mathematical construct
- Shell growth in estuaries
- Shell purse
- Small shelly fauna
References
[edit]Citations
[edit]- ^ab"How are seashells made?".Woods Hole Oceanographic Institution.Archivedfrom the original on 22 March 2022.Retrieved14 May2024.
- ^"Seashell Souvenirs Are Killing Protected Marine Life".Animals.16 July 2018. Archived fromthe originalon 16 July 2018.Retrieved19 March2019.
- ^abc"How are seashells made?".Woods Hole Oceanographic Institution. 2022.Archivedfrom the original on 20 March 2022.Retrieved21 March2022.
- ^Poutiers, J. M. (1998). "Gastropods".FAO Species Identification Guide for Fishery Purposes: The living marine resources of the Western Central Pacific(PDF).Vol. 1. Seaweeds, corals, bivalves and gastropods. Rome: FAO. p. 503.Archived(PDF)from the original on 31 January 2019.Retrieved30 January2019.
- ^Hogendorn, Jan and Johnson Marion: The Shell Money of the Slave Trade. African Studies Series 49,Cambridge University Press,Cambridge,1986.
- ^Ewers, John C."Hair Pipes in Plains Indian AdornmentArchived1 December 2007 at theWayback Machine",Bureau of American Ethnology Bulletin 164,pp. 29–85. United States Government Printing Office, Washington: 1957.
- ^Raichlen, Steven (4 November 1990)."The venerable scallop's versatility makes it a rare culinary blessing".baltimoresun.com.Archivedfrom the original on 8 May 2021.Retrieved12 November2020.
- ^Berrin, Katherine & Larco Museum.The Spirit of Ancient Peru:Treasures from theMuseo Arqueológico Rafael Larco Herrera.New York:Thames and Hudson,1997.
- ^The Legend of the Sand Dollar
- ^abClark, Mitchell (1996)."Some Basics on Shell Trumpets and some very Basics on how to make them".furious.com.Archivedfrom the original on 21 October 2013.Retrieved24 July2016.
- ^Tasmanian Aboriginal shell necklacesArchived12 June 2011 at theWayback Machine,National Museum of Australia.
- ^"Shellwork Sydney Harbour Bridge".National Museum of Australia Collections.Archivedfrom the original on 30 January 2019.
- ^Ferraz, Eduardo; Gamelas, José A. F.; Coroado, João; Monteiro, Carlos; Rocha, Fernando (12 July 2019). "Recycling Waste Seashells to Produce Calcitic Lime: Characterization and Wet Slaking Reactivity".Waste and Biomass Valorization.10(8): 2397–2414.doi:10.1007/s12649-018-0232-y.ISSN1877-2641.
- ^Preservation News.National Trust for Historic Preservation in the United States. 1985. p. 94.
Brittle buildings made of "shellcrete," a seashell-cement mix applied over logs, are risky to move.
- ^Tunnell, John Wesley (2010).Encyclopedia of Texas Seashells.Texas A&M U. Press. pp. 17–19.ISBN978-1-60344-337-1.
Many impressive old homes and public buildings, as well as more mundane structures such as cisterns and curbs, were constructed of shellcrete bricks in Corpus Christi, Galveston, and other cities along the coast. However, very few exist today.
- ^ Madl, P. & Yip, M. (2000)."PART-III Cnidaria (Gk. cnidos, stinging nettle) reproduction and growth of Scleractinia".Field Excursion to Milne Bay Province – Papua New Guinea Working Group: Scleractinian Corals (incl. Porifera).biophysics.sbg.ac.at. Archived fromthe originalon 28 January 2012.Retrieved31 March2006.
Sources
[edit]- 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,ISBN0-525-93269-0.
- Abbott R. Tucker, 1985,Seashells of the World: a guide to the better-known species,1985, Golden Press, New York,ISBN0-307-24410-5.
- Abbott, R. Tucker, 1986,Seashells of North America,St. Martin's Press, New York,ISBN1-58238-125-9.
- Abbott, R. Tucker, 1974,American Seashells,Second edition, Van Nostrand Rheinhold, New York,ISBN0-442-20228-8.
External links
[edit]![](https://upload.wikimedia.org/wikipedia/commons/thumb/9/99/Wiktionary-logo-en-v2.svg/40px-Wiktionary-logo-en-v2.svg.png)
![](https://upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/30px-Commons-logo.svg.png)
![](https://upload.wikimedia.org/wikipedia/commons/thumb/f/fa/Wikiquote-logo.svg/34px-Wikiquote-logo.svg.png)