A shell is a hard, rigid outer layer developed by a wide variety of different animal species, including mollusks, crustaceans, turtles and tortoises, armadillos, and microscopic organisms. Molluscs are animals belonging to the phylum Mollusca. There are around 250000 extant Species within the phylum with an estimated 70000 Structure of crustaceans As Arthropods crustaceans have a stiff Exoskeleton, which must be shed to allow the animal to grow ( Ecdysis or molting Turtles are Reptiles of the Order Testudines (all living turtles belong to the Crown group Chelonia) most of Tortoises or land Turtles are land-dwelling Reptiles of the family of Testudinidae', order Testudines. Armadillos are small Placental Mammals known for having a leathery armor shell Shells are used for protection, locomotion, defence, structure or in ways that relate to feeding. Scientific names for shell types include exoskeleton, armour, test, carapace, cuticle and peltidium. An exoskeleton is an external Skeleton that supports and protects an animal's body in contrast to the internal Endoskeleton of for example a Human. Armor (or armour) in animals is external or superficial protection against attack by predators formed as part of the body (rather than the behavioural use of protective external A carapace is a dorsal section of an Exoskeleton or shell in a number of animal groups In Biology, the term cuticle or cuticula is given to a variety of tough but flexible non-mineral outer coverings of an organism or part of an organism that Peltidium is a prodorsal shield found in animals of the Subphylum Chelicerata, in the Phylum Arthropoda.
The shells that are perhaps most familiar and most commonly encountered, both in the wild and as decorative objects, are seashells. A seashell, also known as a sea shell, is the Common name for a hard protective outer layer a shell or in some cases a " test " that was created These are usually primarily composed of calcium carbonate, which can take different crystalline forms, one being nacre otherwise known as mother of pearl. Calcium carbonate is a Chemical compound with the Chemical formula Ca[[Carbon C]] O 3 Nacre, also known as mother of pearl, is an organic-inorganic Composite material produced by some Mollusks as an inner shell layer
Other kinds of animal shells are made from chitin, bone and cartilage, or silica. Chitin ( C 8 H 13 O 5 N)n (ˈkaɪtən is a long-chain Polymer of a N-acetylglucosamine Bones are rigid organs that form part of the Endoskeleton of Vertebrates They function to move support and protect the various organs of the body produce Cartilage is a type of dense Connective tissue. It is composed of specialized cells called chondrocytes that produce a large amount of extracellular matrix The Chemical compound silicon dioxide, also known as silica or silox (from the Latin " Silex " is an Oxide
Mollusks (also spelled molluscs) can thrive in the sea, in fresh water, or on land. In Japanese cuisine, Geoduck (mirugai is sometimes referred to as "giant clam" The white-lipped snail ( Cepaea hortensis) is a medium-sized Species of air-breathing land Snail, a terrestrial Pulmonate The Pulmonata or "pulmonates" are an order (once a Subclass) of Snails and Slugs that have developed a pallial Lung
The majority of shell-forming marine mollusks belong to two classes: Gastropoda (univalves, or snails) and Bivalvia (bivalves, including clams, oysters, and scallops). A seashell, also known as a sea shell, is the Common name for a hard protective outer layer a shell or in some cases a " test " that was created The gastropod shell is a shell which is part of the body of a gastropod or Snail. The bivalve shell is one kind of Seashell, and in life it is composed of two parts two valves The tusk shells or scaphopods are a class of marine Mollusks which vary in size from very small to medium sized Marine is an Umbrella term. As an adjective it is usually applicable to things relating to the Sea or Ocean, such as Marine biology, Marine A class is the Taxonomic rank in the Biological classification of organisms in Biology below phylum and above order. The class Gastropoda or the gastropods, also previously known as gasteropods, or univalves, and more commonly known as Snails Bivalves are Molluscs belonging to the class Bivalvia. They have two-part shells and typically both valves are symmetrical along the hinge line Smaller shell-bearing classes include Scaphopoda (tusk shells), Polyplacophora (chitons, which have eight articulating shelly plates), and Monoplacophora (single-shelled chiton-like animals). The tusk shells or scaphopods are a class of marine Mollusks which vary in size from very small to medium sized Chitons are small to large primitive marine Mollusks in the class Polyplacophora. Monoplacophora, meaning “bearing one plate” is a class of shelled Mollusks These organisms were known only from the Fossil record ranging from the Nautiluses are the only extant cephalopods which have an external shell, although octopuses, cuttlefish and squid have small internal shells. Nautilus (from Greek ναυτίλος, 'sailor' is the common name of any marine creatures of the Cephalopod family Nautilidae, the sole The cephalopods ( Greek plural (kephalópoda "head-feet" are the Mollusc class Cephalopoda characterized by The Cuttlefish are marine animals of the order Sepiida belonging to the Cephalopoda class (which also includes Squid, Octopuses Squid are marine Cephalopods of the order Teuthida, which comprises around 300 species
A mollusk shell is formed, repaired and maintained by a part of the anatomy called the mantle. The mantle is an important part of the anatomy of Molluscs It is the dorsal body wall which covers the visceral mass Any injuries to or abnormal conditions of the mantle are usually reflected in the shape and form and even color of the shell.
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 used to be, and to a minor extent still are, used interchangeably, even by scientists (this is more common in Europe). Malacology is the branch of Invertebrate Zoology which deals with the study of Mollusks the second-largest Phylum of animals in terms of described Conchology is the scientific, semi-scientific or Amateur study of mollusk shells (in the UK spelled mollusc shells The word "conchology" is also sometimes used to describe the hobby of seashell collecting.
In fresh water,shell-bearing mollusks are represented by families from the orders Unionoida (freshwater mussels) and Veneroida (clams, cockles and zebra mussels), as well as the class Gastropoda (which includes freshwater snails). Freshwater is a word that refers to bodies of water such as Ponds lakes rivers and streams containing low concentrations of dissolved Salts and other Total dissolved Unionoida is an order within the class Bivalvia. Members of the order Unionoida which includes the pearly freshwater Mussels are found on six continents The Veneroida or veneroids are an order of Bivalve Molluscs They include some familiar forms such as saltwater Clams and The class Gastropoda or the gastropods, also previously known as gasteropods, or univalves, and more commonly known as Snails
The class Gastropoda also includes many land snails, most of which are of the order Pulmonata and breathe air. The Pulmonata or "pulmonates" are an order (once a Subclass) of Snails and Slugs that have developed a pallial Lung Although the great majority of land snails are small and inconspicuous, the large and highly-colored shells of some tropical species are prized by collectors. In certain tropical islands such as Cuba, or Papua New Guinea, there are almost as many species of land snails as there are of marine. Land snails cannot disperse very easily, so populations frequently become isolated from each other, resulting in situations where adjacent islands, or even adjacent valleys separated by hills or mountains, contain closely-related but clearly separate species of land snails.
A large variety of other animal taxa form exoskeletons of calcium carbonate, chitin or silica. Diatoms ( Greek: (dia = "through" + (temnein = "to cut" i
The brachiopods, or lamp shells, superficially resemble clams, but the phylum is completely unrelated to mollusks. Brachiopods (from Latin brachium, arm + New Latin -poda, foot are a small phylum of Benthic Invertebrates Also Most lines of brachiopods were ended during the Permian-Triassic extinction event, and their ecological niche filled by bivalves. The Permian–Triassic (P–Tr extinction event, informally known as the Great Dying, was an Extinction event that occurred, and 70 percent of terrestrial
Corals are small anemone-like polyps which secrete aragonite (a form of calcium carbonate) to form a hard skeleton. Corals are Marine organisms from the class Anthozoa and exist as small Sea anemone –like Polyps typically in colonies of many Aragonite is a Carbonate mineral, one of the two common naturally occurring polymorphs of Calcium carbonate, Ca[[carbon C]] O 3 Calcium carbonate is a Chemical compound with the Chemical formula Ca[[Carbon C]] O 3 The many skeletons in a colony aggregate to form coral reefs. Coral reefs are Aragonite structures produced by living organisms found in marine waters with little to no nutrients in the water The construction of the shell-like structures are aided by a symbiotic relationship with a class of algae, zooxanthellae. This article is about the biological phenomenon for other uses see Symbiosis (disambiguation The term symbiosis (from the Greek Algae ( sing. alga are a large and diverse group of simple typically Autotrophic organisms ranging from Unicellular to Multicellular forms Zooxanthellae (plural ˌzoʊoʊzænˈθɛli are golden-brown intracellular Endosymbionts of various marine Animals and Protozoa, especially Anthozoans
Some echinoderms (starfish, sea urchins, sand dollars) and some polychaetes (annelid worms) also have hard exoskeletons. Echinoderms (Phylum Echinodermata) are a phylum of marine Animals (including Sea stars) Starfish (also called sea stars) are any Echinoderms belonging to the class Asteroidea. Sea urchins are small globular spiny sea cat animals composing most of class Echinoidea. Sand dollars (order Clypeasteroida are flat round marine animals related to sea urchins ( Echinoids, sea stars and other echinoderms The Polychaeta or polychaetes are a class of Annelid worms generally marine The now-extinct ostracoderms ("shell-skins") were a type of armoured marine fish which flourished in North America and Europe during the Ordovician, Silurian and Devonian geological periods. Ostracoderms ("shell-skinned" are any of several groups of extinct, primitive jawless Fishes that were covered in an armor of bony plates The Ordovician is a geologic period and system, the second of six of the Paleozoic era, and covers the time between 488 The Silurian is a geologic period and system that extends from the end of the Ordovician period about 443 The Devonian is a geologic period and system of the Paleozoic era spanning from to  million years ago.
Many arthropods have a cuticle made up of sclerites, or hardened body parts, which form a stiff exoskeleton formed mostly of chitin. Arthropods are Animals belonging to the Phylum Arthropoda (from Greek ἄρθρον arthron, " Joint " In Biology, the term cuticle or cuticula is given to a variety of tough but flexible non-mineral outer coverings of an organism or part of an organism that A sclerite ( Greek skleros meaning " hard " is a hardened body part Chitin ( C 8 H 13 O 5 N)n (ˈkaɪtən is a long-chain Polymer of a N-acetylglucosamine For mechanical strength, some crustaceans, myriapods and trilobites impregnate the cuticle with mineral salts, especially calcium carbonate, which can make up up to 40% of the cuticle.
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. Structure of crustaceans As Arthropods crustaceans have a stiff Exoskeleton, which must be shed to allow the animal to grow ( Ecdysis or molting The Malacostraca (Greek "soft shell" are the largest class of Crustaceans and include most of the animals that non-experts recognize as crustaceans including A carapace is a dorsal section of an Exoskeleton or shell in a number of animal groups
The rigid part of an insect's exoskeleton is called the procuticle; when outgrown, this construct must be shed during moulting. Insects ( Class Insecta) are a major group of Arthropods and the most diverse group of Animals on the Earth with over a million described The procuticle is the major portion of the Exoskeleton of an Insect (and various other Arthropods; its exact composition and structure may differ somewhat Ecdysis is the Molting of the Cuticula in Arthropods and related groups ( Ecdysozoa) Arachnids (spiders, scorpions, harvestmen, ticks, and mites) have a peltidium made up of several plates which may or may not be fused. Arachnids are a class ( Arachnida) of joint-legged Invertebrate Animals in the subphylum Chelicerata. Peltidium is a prodorsal shield found in animals of the Subphylum Chelicerata, in the Phylum Arthropoda. Myriapods (centipedes and millipedes) have overlapping scales of chitin, which are quite hard in some species. Myriapoda is a Subphylum of Arthropods containing Millipedes Centipedes and others
A few mammals have developed hard, shell-like armour. Armor (or armour) in animals is external or superficial protection against attack by predators formed as part of the body (rather than the behavioural use of protective external The shell of the armadillo is formed by plates of dermal bone covered in small, overlapping epidermal scutes. Armadillos are small Placental Mammals known for having a leathery armor shell The pangolin or scaly anteater has armoured plates made up of hair, similar to the horn of the rhinoceros. Rhinoceros (raɪˈnɒsərəs often colloquially abbreviated rhino, is a name used to group five extant species of Odd-toed ungulates in the family
Echidna, spiny anteaters, porcupines and hedgehogs use spines of hardened keratin as a form of protection. Echidnas (ɨˈkɪdnə also known as spiny anteaters, are four extant Mammal species belonging to the Tachyglossidae family of the Echidnas (ɨˈkɪdnə also known as spiny anteaters, are four extant Mammal species belonging to the Tachyglossidae family of the Porcupines are Rodents with a coat of sharp spines or quills that defend them from predators A hedgehog is any of the small spiny Mammals of the Subfamily Erinaceinae and the order Erinaceomorpha. A spine is a hard thorny or needle-like structure which occurs on various animals Keratins are a family of fibrous structural proteins; tough and insoluble they form the hard but nonmineralized structures found in Reptiles Birds
Turtles, tortoises and terrapins form a hard carapace and plastron of bone and cartilage which is developed from their ribs. Turtles are Reptiles of the Order Testudines (all living turtles belong to the Crown group Chelonia) most of Tortoises or land Turtles are land-dwelling Reptiles of the family of Testudinidae', order Testudines. A carapace is 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 Turtle or Tortoise, what one would call the belly similar in composition to the Carapace Bones are rigid organs that form part of the Endoskeleton of Vertebrates They function to move support and protect the various organs of the body produce Cartilage is a type of dense Connective tissue. It is composed of specialized cells called chondrocytes that produce a large amount of extracellular matrix In Vertebrate Anatomy, ribs ( Latin costae) are the long curved Bones which form the ribcage.
A crocodile exoskeleton is formed of bony scutes and horn-like scales. The crocodile exoskeleton consists of the protective dermal and epidermal components of the Integumentary system in animals of the order In most biological nomenclature a scale ( Greek lepid, Latin squama) is a small rigid plate that grows out of an Animal
Plant-like diatoms and animal-like radiolarians are two forms of plankton which form hard silicate shells. Ankylosauria is a group of Herbivorous Dinosaurs of the order Ornithischia. Known colloquially as stegosaurs the Stegosauria are a group of herbivorous Dinosaurs of the Jurassic and Early Cretaceous Periods Diatoms ( Greek: (dia = "through" + (temnein = "to cut" i Radiolarians (also radiolaria) are Amoeboid Protozoa that produce intricate Mineral Skeletons typically with a central capsule Plankton consist of any drifting Organisms ( Animals Plants Archaea, or Bacteria) that inhabit the Pelagic zone of The Chemical compound silicon dioxide, also known as silica or silox (from the Latin " Silex " is an Oxide
Protists such as foraminifera, coccolithophores and testate amoebae create shells called "tests" of calcium carbonate. The Foraminifera, ("Hole Bearers" or forams for short are a large group of Amoeboid Protists with reticulating Pseudopods fine Coccolithophores (also called coccolithophorids) are single-celled Algae, Protists and Phytoplankton belonging to the Division Testate amoebae (Protozoa Rhizopods are single-celled Protists partially enclosed in a simple test (shell
Throughout the history of humanity, shells of many types and from many different kinds of animals have been popular as human adornments.
Seashells are often used whole and drilled so that they can be threaded like a bead, or cut into pieces of various shapes. A seashell, also known as a sea shell, is the Common name for a hard protective outer layer a shell or in some cases a " test " that was created Shells have been formed or incorporated into pendants, beads, buttons, brooches, rings, and hair combs, among other uses. A bead is a small decorative object that is pierced for threading or stringing In Clothing and Fashion design, a button is a small plastic or metal disc- or knob-shaped typically round object usually attached to an article of Clothing A brooch (also known in ancient times as a fibula, and not to be confused with broach) is a Decorative jewelry item designed to be attached to A finger ring is a band worn as a type of ornamental Jewellery around a finger it is the most common current meaning of the word ring. A comb is a device made of solid material generally flat always toothed and is used in hair care for straightening and cleaning hair or other fibers Tortoiseshell has been used for jewelry and hair combs, and for many other items as varied as inkwells, sunglasses, guitar picks, and knitting needles. Tortoiseshell is a material produced mainly from the shell of the Hawksbill turtle, an endangered species An inkwell is a small jar or container often made of Glass, Porcelain, Silver, Brass, or Pewter, that is used for holding Sunglasses or sun glasses are a visual aid variously termed Spectacles or Glasses, which feature lenses that are coloured or darkened to prevent strong A guitar pick is a type of Plectrum designed for use on a Guitar. A knitting needle or knitting pin is a Tool in Hand-knitting to produce Knitted fabrics They generally have a long shaft and taper
The Moche culture of ancient Peru worshipped animals and the sea and often depicted shells in their art. The Moche civilization (alternately the Mochica culture Early Chimu Pre-Chimu Proto-Chimu etc Peru (Perú Piruw Piruw officially the Republic of Peru ( reˈpuβlika del peˈɾu is a country in western South America.  Some tribes of the indigenous peoples of the Americas used shells for wampum and hair pipes. For indigenous peoples in the United States other than Hawaii and Alaska see also Native Americans in the United States. Wampum is a string of creamy white colored shell beads fashioned from the North Atlantic Channeled whelk ( Busycotypus canaliculatus) shell and is traditionally used A Hair Pipe is a term for a long narrow Bead, more than 15 inches long which were popular with American Indians. 
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. Art History Mosaics of the 4th century BC are found in the Macedonian palace-city of Aegae, and they enriched the floors of Hellenistic Inlay is a decorative technique of inserting pieces of coloured materials into depressions in a base object to form patterns or pictures Large numbers of whole seashells, arranged to form patterns, have been used to decorate mirror frames, furniture and man-made grottos. A grotto (Italian grotta) is any type of natural or artificial Cave that is associated with modern historic or prehistoric use by humans