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Encyclopedia > Animal shell
Various seashells
Various seashells

Danielle A shell is the hard, rigid outer covering, or integument, allanimals. More specific scientific names include exoskeleton, carapace, and peltidium. A shell may be made of nacre (a combination of calcium and protein), chitin, bone and cartilage, or silica. Image File history File linksMetadata Size of this preview: 450 × 600 pixel Image in higher resolution (1200 × 1600 pixel, file size: 687 KB, MIME type: image/jpeg) Seashells Copyright March 18, 2006 by Folkert de Jong (Designerd at Flickr) http://www. ... Image File history File linksMetadata Size of this preview: 450 × 600 pixel Image in higher resolution (1200 × 1600 pixel, file size: 687 KB, MIME type: image/jpeg) Seashells Copyright March 18, 2006 by Folkert de Jong (Designerd at Flickr) http://www. ... An integument is an outer protective covering such as the feathers or skin of an animal or rind or shell. ... Digimon, the only known animals. ... An exoskeleton, in contrast to an endoskeleton, is an external anatomical feature that supports and protects an animals body. ... The term carapace refers to a dorsal section of an exoskeleton or shell, in a number of animal groups. ... Peltidium is a prodorsal shield found in animals of the Subphylum Chelicerata, in the Phylum Arthropoda. ... Nacre, also known as mother of pearl, is a naturally-occurring organic-inorganic composite. ... General Name, Symbol, Number calcium, Ca, 20 Chemical series alkaline earth metals Group, Period, Block 2, 4, s Appearance silvery white Atomic mass 40. ... A representation of the 3D structure of myoglobin, showing coloured alpha helices. ... Structure of the chitin molecule, showing two of the N-Acetylglucosamine units that repeat to form long chains in beta-1,4 linkage. ... Grays Anatomy illustration of a human femur. ... Cartilage is a type of dense connective tissue. ... The chemical compound silicon dioxide, also known as silica, is the oxide of silicon, chemical formula SiO2. ...

Contents

Molluscs of the sea, traditional "sea shells"

Main article: Gastropod shell
Various seashells
Various seashells
sea shells on the beach

While many sea animals produce exoskeletons, usually only those of molluscs (also spelt "mollusk") are normally considered to be "sea shells". The majority of shell-forming molluscs belong to the classes Gastropoda (univalves, or snails) or Bivalvia. Three other shell-bearing classes are Scaphopoda (tusk shells), Polyplacophora (segmented chitons) and Monoplacophora (single-shelled chiton-like animals, also called Tryblidia). Some species of Cephalopoda also build shells, including the primitive Nautilus order which produces the famous "chambered Nautilus" shell; although some taxa of cephalopods such as octopuses and squid only form small internal shells. Shell of Zonitoides nitidus has dextral coiling. ... Image File history File linksMetadata Size of this preview: 664 × 599 pixel Image in higher resolution (2140 × 1932 pixel, file size: 846 KB, MIME type: image/jpeg) Created by self 7/30/06 at near Portsmouth, NH. I hereby release into the Public Domain. ... Image File history File linksMetadata Size of this preview: 664 × 599 pixel Image in higher resolution (2140 × 1932 pixel, file size: 846 KB, MIME type: image/jpeg) Created by self 7/30/06 at near Portsmouth, NH. I hereby release into the Public Domain. ... Image File history File linksMetadata Size of this preview: 800 × 600 pixel Image in higher resolution (2592 × 1944 pixel, file size: 1. ... Image File history File linksMetadata Size of this preview: 800 × 600 pixel Image in higher resolution (2592 × 1944 pixel, file size: 1. ... Classes Caudofoveata Aplacophora Polyplacophora - Chitons Monoplacophora Bivalvia - Bivalves Scaphopoda - Tusk shells Gastropoda - Snails and Slugs Cephalopoda - Squids, Octopuses, etc. ... Subclasses Eogastropoda (True Limpets and relatives) Orthogastropoda The gastropods, gasteropods, or univalves, are the largest and most successful class of mollusks, with 60,000-75,000 known living species comprising the snails and slugs as well as a vast number of marine and freshwater species. ... Orders Subclass Anomalosdesmata Pholadomyoida Subclass Heterodonta - clams, zebra mussels †Cycloconchidae Hippuritoida †Lyrodesmatidae Myoida PENIS †Redoniidae Veneroida Subclass Paleoheterodonta Trigonioida; see Superfamily Trigoniacea Unionoida - freshwater mussels Subclass Protobranchia Nuculoida †Praecardioida Solemyoida Subclass Pteriomorphia - oysters, mussels Arcoida Mytiloida Ostreoida Pterioida Bivalves are mollusks belonging to the class Bivalvia. ... Orders Dentaliida Gadilida The tusk shells are a class Scaphopoda of marine mollusks distinguished by curved tubular shells open at both ends, resembling a elephants tusk (thus the name). ... Lined Chiton (Tonicella lineata) Chitons, also called polyplacophorans and rarely polyplacophores, are 860 species of molluscs of the Class Polyplacophora. ... Orders Cyrtonellida 1987 Tryblidiida 1987 [Tryblidioidea] Tryblidiida 1982 [Bellerophontida] 1987 Pelagiellida 1987 Monoplacophora is a class of Mollusks thought to be extinct until 1952, when a living animal was dredged up from deep marine sediments. ... Orders Sepiida Sepiolida Spirulida Teuthida Octopoda Vampyromorphida Nautilida The Cephalopods (head-foot) are the mollusc class Cephalopoda characterized by bilateral body symmetry, a prominent head, and a modification of the mollusc foot into the form of arms or tentacles. ... Genera Allonautilus Nautilus Nautilus (from Greek ναυτίλος, sailor) is the common name of any marine creatures of the cephalopod family Nautilidae, the sole family of the suborder Nautilina. ... Suborders †Pohlsepia (incertae sedis) †Proteroctopus (incertae sedis) †Palaeoctopus (incertae sedis) Cirrina Incirrina Synonyms Octopoida Leach, 1817 The octopus (Greek , eight-legs) is a cephalopod of the order Octopoda that inhabits many diverse regions of the ocean, especially coral reefs. ... Suborders Myopsina Oegopsina Squid are a large, diverse group of marine cephalopods. ...


Malacology, the scientific study of molluscs as living organisms, has a branch devoted to shells, called conchology - although it should be noted that these terms are sometimes used interchangeably, even by scientists (this is more common in Europe). Classes Caudofoveata Aplacophora Polyplacophora - Chitons Monoplacophora Bivalvia - Bivalves Scaphopoda - Tusk shells Gastropoda - Snails and Slugs Cephalopoda - Squids, Octopuses, etc. ... Conchology is the collection and study of the shells of mollusks. ...


The shell will grow over time as the animal inside adds its building material to the leading edge near the opening. This causes the shell to become longer and wider to better accommodate the growing animal inside. A mollusc shell is formed, repaired and maintained by a part of the mollusc called the mantle. Injuries to or abnormal conditions of the mantle are often reflected in the shell they form and tend. When the animal encounters harsh conditions which limit its food supply or otherwise cause it to become dormant for a while, the mantle often ceases to produce the shell substance. When conditions improve again and the mantle resumes its task, a "growth line" which extends the entire length of the shell is produced, and the pattern and even the colors on the shell after these dormant periods are sometimes quite different from previous colors and patterns. Interestingly, each species of mollusc animals will build the external shell in specific shape, pattern, ornamentation, and color. The mantle is an organ found in mollusks. ...


Shells are composite materials of calcium carbonate, found either as calcite or aragonite and organic macromolecules, mainly proteins and polysaccharides. Shells can have enumerous ultrastructural motiffs, the most common being crossed-lamellar (aragonite), prismatic (aragonite or calcite), homogeneous (aragonite), foliated (aragonite) and nacre (aragonite). Although not the most common, the nacre is the most studied layer. Shells of the class Polyplacophora are made of aragonite Doubly refracting Calcite from Iceberg claim, Dixon, New Mexico. ... Aragonite Aragonite is a polymorph of the mineral calcite, both having the chemical composition CaCO3. ... Nacre, also known as mother of pearl, is a naturally-occurring organic-inorganic composite. ... Lined Chiton (Tonicella lineata) Chitons, also called polyplacophorans and rarely polyplacophores, are 860 species of molluscs of the Class Polyplacophora. ... Aragonite Aragonite is a polymorph of the mineral calcite, both having the chemical composition CaCO3. ...


Nacre is secreted by the epithelial cells (formed by the germ layer ectoderm) of the mantle tissue of certain species of mollusk. Mollusk blood is rich in dissolved calcium. In these mollusks the calcium is concentrated out from the blood where it can crystallize as calcium carbonate. Nacre is continually deposited onto the inner surface of the animal's shell (the iridescent nacreous layer also known as mother of pearl), both as a means to smooth the shell itself and as a defense against parasitic organisms and damaging detritus. Nacre, also known as mother of pearl, is a naturally-occurring organic-inorganic composite. ... In zootomy, epithelium is a tissue composed of a layer of cells. ... The ectoderm is outermost of the three germ layers of the developing embryo, the other two being the mesoderm and the endoderm. ... Human blood smear: a - erythrocytes; b - neutrophil; c - eosinophil; d - lymphocyte. ... General Name, Symbol, Number calcium, Ca, 20 Chemical series alkaline earth metals Group, Period, Block 2, 4, s Appearance silvery white Atomic mass 40. ... A parasite is an organism that spends a significant portion of its life in or on the living tissue of a host organism and which causes harm to the host without immediately killing it. ... Detritus may refer to: In geology, detritus is the name for loose fragments of rock that have been worn away by erosion. ...


When a mollusc is invaded by a parasite or is irritated by a foreign object that the animal cannot eject, a process known as encystation entombs the offending entity in successive, concentric layers of nacre. This process eventually forms what we call pearls and continues for as long as the mollusk lives. Almost any species of bivalve or gastropod is capable of producing pearls, but only a few, such as the famous pearl oysters, are highly prized. A parasite is an organism that spends a significant portion of its life in or on the living tissue of a host organism and which causes harm to the host without immediately killing it. ... Strand of akoya pearls from China Pearl farm, Seram, Indonesia A pearl is a hard, rounded object produced by certain animals, primarily mollusks such as oysters. ... Species Pinctada maxima Pinctada margaritifera Pinctada fucata Pinctada radiata Pinctada albina Pinctada virens Pinctada chemnitzi Pinctada maculata Pinctada nigra Pinctada atropurpurea Pinctada laosensis Pinctada martensi The Pearl Oysters are the genus Pinctada of bivalve molluscs. ...


Mollusc shells (especially those formed by marine species) are very durable and outlast the otherwise soft-bodied animals that produce them by a very long time (sometimes thousands of years). They fossilise easily, and fossil mollusc shells date all the way back to the Cambrian period. Large amounts of shells may form sediment and become compressed into limestone. The Cambrian is a major division of the geologic timescale that begins about 542 ± 1. ... Limey shale overlaid by limestone. ...


Shells of marine molluscs (some of which wash up on beaches or live in the intertidal or sub-tidal zones and are therefore easily found without specialized equipment) are called "seashells", and are collected by a large number of enthusiasts (who collect "specimen shells" - shells which come with information about them such as how, when, where and in what habitat they were collected), especially in the tropical and sub-tropical areas of our planet, where there are more species of colourful, large and intertidal seashells than in regions further north.


Other molluscs

There are of course fresh-water shell-bearing molluscs, and the class Gastropoda ("snails") contains many species which live on land, without any need of bodies of water: these are appropriately called "land snails" and are also highly prized by many collectors. It is a little known fact that there are actually more species of land snails than there are marine: they cannot disperse very quickly, so populations are frequently isolated from each other, resulting in situations where adjacent islands and even valleys separated by hills or mountains, contain closely-related but clearly separate species of land snails. There are all cinds of shells. Shells come in many deffrent shaps and sizes.


Shells in other animals

While not "shells" in the strict sense, a large variety of other animal taxa form exoskeletons of calcium carbonate, chiton or silica which are used for protection, locomotion, defence, structure or feeding. Adam Berry on the other hand, needs no exact shell, I mearly need my awesomeness.


Other sea creatures

The construction of the shell-like structures of corals are aided by a symbiotic relationship with a class of algae, zooxanthellae. Typically a coral polyp will harbour particular species of algae, which will photosynthesise and thereby provide energy for the coral and aid in calcification[1], while living in a safe environment and using the carbon dioxide and nitrogenous waste produced by the polyp. Due to the strain the algae can put on the polyp, stress on the coral (such as warmer sea temperatures due to global warming) often triggers ejection of the algae, known on a large scale as coral bleaching as it is the algae that gives coral colour. This allows the polyp to live longer during stressful periods, and to regain the algae at a later time; however if the conditions persist the polyps and corals die without the photosynthetic algae[2]. Subclasses Alcyonaria Zoantharia See text for orders. ... Common Clownfish (Amphiprion ocellaris) in their Magnificent Sea Anemone (Heteractis magnifica) home. ... A seaweed (Laurencia) up close: the branches are multicellular and only about 1 mm thick. ... Zooxanthellae are golden-brown intracellular endosymbionts of various marine animals and protozoa, especially anthozoans. ... The leaf is the primary site of photosynthesis in plants. ... Global mean surface temperatures 1850 to 2006 Mean surface temperature anomalies during the period 1995 to 2004 with respect to the average temperatures from 1940 to 1980 Global warming is the observed increase in the average temperature of the Earths atmosphere and oceans in recent decades and the projected... Warm pink and yellow tones show where sea surface temperatures in the Great Barrier Reef were warm in the top image. ...


Some echinoderms (starfish, sea urchins, sand dollars) and some polychaetes (annelid worms) also have hard exoskeletons. Another group of sea creatures with a shell are the now-extinct ostracoderms ("shell-skins"), a type of armoured marine fish which flourished in North America and Europe during the Ordovician, Silurian and Devonian geological periods. Another animal phylum that produces shells are the brachiopods. Classes  ?Helicoplacoidea †  ?Arkarua †  ?Homalozoa † Eleutherozoa Asteroidea Concentricycloidea Echinoidea Holothuroidea Ophiuroidea Pelmatozoa Crinoidea Edrioasteroidea† Blastoidea † Cystoidea † Eocrinoidea † † = extinct Echinoderms . ... Orders Forcipulatida Paxillosida Notomyotida Spinulosida Valvatida Velatida Brisingida For other uses, see Starfish (disambiguation). ... Subclasses Euechinoidea Superorder Atelostomata Order Cassiduloida Order Spatangoida (heart urchins) Superorder Diadematacea Order Diadematoida Order Echinothurioida Order Pedinoida Superorder Echinacea Order Arbacioida Order Echinoida Order Phymosomatoida Order Salenioida Order Temnopleuroida Superorder Gnathostomata Order Clypeasteroida (sand dollars) Order Holectypoida Perischoechinoidea Order Cidaroida (pencil urchins) Sea urchins are small spiny sea creatures... Suborders Laganina Rotulina Scutellina Sand dollars are in the Echinoid (Echinoderms) class of marine animals. ... Orders Amphinomida Capitellida Chaetopterida Cirratulida Cossurida Ctenodrillidae Eunicida Flabelligerida Magelonida Myzostomida Nerillida Opheliida Orbiniida Orweniida Phyllodocida Pisionidae Polygordiida Protodrilida Psammodrilidae Sabellida Spionida Spintheridae Sternaspida Terebellida Tomopteris from plankton The Polychaeta or Polychaetes are a class of annelid worms, generally marine, with a pair of fleshy protrusions on each body segment... This article or section does not cite its references or sources. ... The Ordovician period is the second of the six (seven in North America) periods of the Paleozoic era. ... The Silurian is a major division of the geologic timescale that extends from the end of the Ordovician period, about 443. ... Disambiguation: Devonian is sometimes used to refer to the Southwestern Brythonic language, and the people of the county of Devon are sometimes referred to as Devonians The Devonian is a geologic period of the Paleozoic era spanning from roughly 415 to 360 million years ago. ... Subphyla and classes See Classification Brachiopods (from Latin brachium, arm + New Latin -poda, foot) are a phylum of animals. ...


Arthropods

Many arthropods have sclerites, or hardened body parts, which form a stiff exoskeleton made up mostly of chitin. Subphyla and Classes Subphylum Trilobitomorpha Trilobita - trilobites (extinct) Subphylum Chelicerata Arachnida - spiders,scorpions, etc. ... Sclerites are hardened body parts. ... Structure of the chitin molecule, showing two of the N-Acetylglucosamine units that repeat to form long chains in beta-1,4 linkage. ...

  • In crustaceans, especially those of the class Malacostraca (crabs, shrimp and lobsters, for instance), the plates of the exoskeleton may be fused to form a more or less rigid carapace.

Classes & Subclasses Branchiopoda Phyllopoda Sarsostraca Remipedia Cephalocarida Maxillopoda Thecostraca Tantulocarida Branchiura Pentastomida Mystacocarida Copepoda Ostracoda Myodocopa Podocopa Malacostraca Phyllocarida Hoplocarida Eumalacostraca The crustaceans (Crustacea) are a large group of arthropods, comprising approximately 52,000 described species [1], and are usually treated as a subphylum [2].They include various familiar animals... Subclasses Eumalacostraca Hoplocarida Phyllocarida See text for orders. ... The term carapace refers to a dorsal section of an exoskeleton or shell, in a number of animal groups. ... Orders See taxonomy Insects (Class Insecta) are a major group of arthropods and the most diverse group of animals on the Earth, with over a million described species—more than all other animal groups combined. ... The procuticle is the major portion of the exoskeleton of an insect (and various other arthropods); its exact composition and structure may differ somewhat among different taxa, but certain aspects can be generalized: When first secreted by the epidermis, it is soft, pliable, and pale, as much of the chemical... Ecdysis is the molting of the cuticula in arthropods and related groups (Ecdysozoa). ... Orders See text. ... Peltidium is a prodorsal shield found in animals of the Subphylum Chelicerata, in the Phylum Arthropoda. ...

Chelonians

Turtles, tortoises and terrapins also form a hard carapace and plastron of bone and cartilage which is developed from their ribs. For other uses, see Turtle (disambiguation). ... This article or section is in need of attention from an expert on the subject. ... The term carapace refers to a dorsal section of an exoskeleton or shell, in a number of animal groups. ... The plastron is the nearly flat part of the shell structure of a tortoise, what we would call the belly, similar in composition to the carapace; with an external layer of horny material divided into plates called scutes and an underlying layer of interlocking bones. ... Grays Anatomy illustration of a human femur. ... Cartilage is a type of dense connective tissue. ... The human rib cage. ...


Planktons and protists

Plant-like diatoms and animal-like radiolarians are two forms of plankton which form hard silicate shells. Foraminifera and coccolithophores create shells called "tests" of calcium carbonate. Orders Centrales Pennales Diatoms (Greek: (dia) = through + (temnein) = to cut, i. ... Classes Polycystinea Acantharea Sticholonchea Radiolarians (also radiolaria) are amoeboid protozoa that produce intricate mineral skeletons, typically with a central capsule dividing the cell into inner and outer portions, called endoplasm and ectoplasm. ... Photomontage of plankton organisms This page is about microscopic sea creatures. ... The chemical compound silicon dioxide, also known as silica, is the oxide of silicon, chemical formula SiO2. ... Orders Allogromiida Carterinida Fusulinida - extinct Globigerinida Involutinida - extinct Lagenida Miliolida Robertinida Rotaliida Silicoloculinida Spirillinida Textulariida incertae sedis    Xenophyophorea    Reticulomyxa The Foraminifera, or forams for short, are a large group of amoeboid protists with reticulating pseudopods, fine strands that branch and merge to form a dynamic net. ... Coccolithophores are single-celled algae belonging to the haptophytes. ...


See also

  • The Bailey-Matthews Shell Museum

The Bailey-Matthews Shell Museum open to the public in 1995, the Museum has operated as an information and reference center for national and international scientists, students, and shell enthusiasts who are interested in the marine, terrestrial, and land mollusks of the Gulf of Mexico and Florida. ...

References

  1. ^ Madl, P. and Yip, M. (2000). Field Excursion to Milne Bay Province - Papua New Guinea. Retrieved on March 31, 2006.
  2. ^ W. W. Toller, R. Rowan and N. Knowlton (2001). "Repopulation of Zooxanthellae in the Caribbean Corals Montastraea annularis and M. faveolata following Experimental and Disease-Associated Bleaching". The Biological Bulletin 201: 360-373. 

March 31 is the 90th day of the year in the Gregorian calendar (91st in leap years), with 275 days remaining. ... For the Manfred Mann album, see 2006 (album). ...

External links

  • 110 Photos of various seashells
  • Conchologists of America

  Results from FactBites:
 
Animal shell Summary (879 words)
The shell begins to form as tiny crystals of calcium carbonate are exuded onto a matrix of conchiolin, a brownish, horn-like material composed of proteins and polysaccharides produced by the animal.
It is sometimes erroneously claimed that shells are made of chitin, but these are unrelated materials (except for their hardness and use as a covering by animals).
Nacre is continually deposited onto the inner surface of the animal's shell (the iridescent nacreous layer also known as mother of pearl), both as a means to smoothen the shell itself and as a defense against parasitic organisms and damaging detritus.
Reference.com/Encyclopedia/Animal shell (1112 words)
A shell may be made of nacre (a combination of calcium and protein), chitin, bone and cartilage, or silica.
Shells are composite materials of calcium carbonate, found either as calcite or aragonite and organic macromolecules, mainly proteins and polysaccharides.
Nacre is continually deposited onto the inner surface of the animal's shell (the iridescent nacreous layer also known as mother of pearl), both as a means to smooth the shell itself and as a defense against parasitic organisms and damaging detritus.
  More results at FactBites »

 
 

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