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This article is about the mollusk. For the ancient Greek article of dress see chiton (costume). A chiton ( Ancient Greek khitōn (χιτών was a form of clothing in Ancient Greece, worn by both women and men


Chiton
Fossil range: Cambrian - Recent
Lined chiton, Tonicella lineata
Lined chiton, Tonicella lineata
Scientific classification
Kingdom: Animalia
Subkingdom: Metazoa
Phylum: Mollusca
Class: Polyplacophora
Blainville, 1816
Orders, families and genera

See text. The Cambrian is a geologic period and system that began about Ma (million years ago at the end of the Proterozoic eon and ended about Ma with Tonicella lineata, commonly known as the lined chiton, is a species of Chiton. Molluscs are animals belonging to the phylum Mollusca. There are around 250000 extant Species within the phylum with an estimated 70000 Henri Marie Ducrotay de Blainville ( September 12, 1777 - May 1, 1850) was a French Zoologist and Anatomist.

Chitons are small to large, primitive marine mollusks in the class Polyplacophora. 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 Molluscs are animals belonging to the phylum Mollusca. There are around 250000 extant Species within the phylum with an estimated 70000 A class is the Taxonomic rank in the Biological classification of organisms in Biology below phylum and above order. There are 900 to 1,000 extant species of chitons in the class, which was formerly known as Amphineura[1]). Extant is a term commonly used to refer to Taxa (such as Species, genera or families) that are still in existence (living In Biology, a species is one of the basic units of Biological classification and a Taxonomic rank.

These mollusks are also sometimes commonly known as sea cradles or "coat-of-mail shells". They are also sometimes referred to more formally as loricates, polyplacophorans, and rarely as polyplacophores.

Chitons have a shell which is composed of eight separate shell plates. These plates overlap somewhat at the front and back edges, and yet the plates articulate well with one another. Because of this, although the plates provide good protection for impacts from above, they nonetheless permit the chiton to flex upward when needed for locomotion over uneven surfaces, and also the animal can slowly curl up into a ball when it is dislodged from the underlying surface. The shell plates are surrounded by a structure known as a girdle.

The English name "chiton" originates from the Latin word chitōn, which means "mollusk", and in turn is derived from the Greek word "khitōn", meaning tunic (which also is the source of the word chitin). Latin ( lingua Latīna, laˈtiːna is an Italic language, historically spoken in Latium and Ancient Rome. A tunic is any of several types of Clothing for the body with or without Sleeves and of various lengths reaching from the hips to the ankles Chitin ( C 8 H 13 O 5 N)n (ˈkaɪtən is a long-chain Polymer of a N-acetylglucosamine The Greek word "khitōn" can be traced to the Central Semitic word "*kittan", which is from the Akkadian words "kitû" or "kita’um", meaning flax or linen, and originally the Sumerian word "gada" or "gida". [2]

The Greek-derived name Polyplacophora comes from the words poly- (many), plako- (tablet), and -phoros (bearing), a reference to the chiton's eight shell plates.

Contents

Distribution

Chitons live worldwide, in cold water, warm water and in the tropics.

Habitat

Chitons live on hard surfaces such as on or under rocks, or in rock crevices. Some species live quite high in the intertidal zone and are exposed to the air and light for long periods. Others live subtidally. A few species live in deep water, as deep as 6,000 m (about 20,000 ft). The metre or meter is a unit of Length. It is the basic unit of Length in the Metric system and in the International A foot (plural feet or foot; symbol or abbreviation ft or sometimes &prime – the prime symbol) is a non-SI unit

It is worth pointing out that chitons as a molluscan class are exclusively and fully marine. This is in contrast to the bivalves which were able to adapt to brackish water as well as freshwater, and the gastropods which were able to make successful transitions to freshwater and terrestrial environments. Bivalves are Molluscs belonging to the class Bivalvia. They have two-part shells and typically both valves are symmetrical along the hinge line The class Gastropoda or the gastropods, also previously known as gasteropods, or univalves, and more commonly known as Snails

Culinary uses

Chitons are eaten in Tobago and were eaten by native Americans of the Pacific coasts of both North and South America, the foot of the chiton is prepared in a manner similar to abalone. Tobago is the smaller of the two main islands that make up the Republic of Trinidad and Tobago. Abalone (from Spanish Abulón) are medium-sized to very large edible sea Snails marine Gastropod Mollusks in the

Shell description

A chiton shell on display (Acanthopleura spinosa) held in place by metal rods. The anterior end is to the left.
A chiton shell on display (Acanthopleura spinosa) held in place by metal rods. Chitons are small to large primitive marine Mollusks in the class Polyplacophora. The anterior end is to the left.

Chitons have shells made up of eight overlapping calcareous valves held together and surrounded by a girdle. Calcareous refers to a Sediment, Sedimentary rock, or Soil type which is formed from or contains a high proportion of Calcium carbonate in the Valves, when referring to Chitons are eight dorsal, articulated shell plates which are frequently brightly coloured and/or sculptured In many species the surface of the girdle is covered in, or decorated with, scales, hair-like protrusions, or glassy bristles.

After a chiton dies, the individual valves which make up the 8-part shell come apart, and may wash up in beach drift. The individual shelly plates from a chiton are sometimes known as "butterfly shells" because of their shape.

The most anterior plate is crescent shaped, and is known as the cephalic plate (or head plate, although chitons don't have a head). The most posterior plate is known as the anal plate (or the tail plate, although chitons don't have a tail. )

Life habits

A chiton creeps along slowly on a muscular foot, and can cling to rocks very powerfully, like a limpet. The name Limpet is used for many kinds of mostly saltwater but also freshwater Snails specifically those that have a simple shell which is more or less broadly conical

Chitons eat algae, bryozoans, diatoms and sometimes bacteria by scraping the rocky substrate with their well-developed radula. Algae ( sing. alga are a large and diverse group of simple typically Autotrophic organisms ranging from Unicellular to Multicellular forms Bryozoans are tiny colonial Animals that generally build stony Skeletons of Calcium carbonate, superficially similar to Coral (although some Diatoms ( Greek: (dia = "through" + (temnein = "to cut" i The Bacteria ( singular: bacterium) are a large group of unicellular Microorganisms Typically a few Micrometres in length bacteria have The radula is a toothed Chitinous ribbon typically used for scraping cutting and chewing food before it enters the Esophagus.

A few species of chitons are predatory, such as the small western Pacific species Placiphorella velata. The Pacific Ocean is the largest of the Earth 's Oceanic divisions These predatory chitons have an enlarged anterior girdle. They catch other small invertebrates, such as shrimp and possibly even small fish, by holding the girdle up off the surface and then clamping down on the unsuspecting, shelter-seeking prey. An invertebrate is an Animal lacking a Vertebral column. The group includes 98% of all animal Species — all animals except those in the Chordate True shrimp are swimming decapod Crustaceans classified in the Infraorder Caridea, found widely around the world in both fresh

Some chitons exhibit homing behavior, returning to the same spot for the daylight hours and roaming around at night to feed.

Predators

Animals which prey on chitons include seagulls, seastars, crabs, and fish

The largest species of chiton

The largest chiton (up to 33 cm in length) is the brick-red gumboot chiton of the Pacific Northwest, in which the valves are completely internal. Gulls (often informally Seagulls) are birds in the family Laridae Starfish (also called sea stars) are any Echinoderms belonging to the class Asteroidea. Crabs are decapod Crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (βραχύ / brachy Fish are aquatic Vertebrate animals that are typically ectothermic (previously Cold-blooded) covered with scales, and equipped with two A centimetre ( American spelling: centimeter, symbol cm) is a unit of Length in the Metric system, equal to one hundredth The gumboot chiton, Cryptochiton stelleri, also known as the giant pacific chiton, is the largest of the Chitons growing to 33  cm (13 in The Pacific Northwest is a region in the northwest of North America (the term refers to the land not the ocean

Anatomy

Ontogeny of Polyplacophora: First image is trochophore, second is stadium in metamorphosis, third is juvenile Polyplacophora.
Ontogeny of Polyplacophora: First image is trochophore, second is stadium in metamorphosis, third is juvenile Polyplacophora. A trochophore (ˈtrɒkəfɔər also spelled trocophore) is a type of marine Larva with several bands of Cilia.

The calcareous valves that chitons carry dorsally are protective, made wholly of aragonite, and variously colored, patterned, smooth or sculptured. Valves, when referring to Chitons are eight dorsal, articulated shell plates which are frequently brightly coloured and/or sculptured In Anatomy, the dorsum is the upper side of animals that typically run fly or swim in a horizontal position and the back side of animals (like humans that walk upright Aragonite is a Carbonate mineral, one of the two common naturally occurring polymorphs of Calcium carbonate, Ca[[carbon C]] O 3 The shell is divided into eight articulating valves embedded in the tough muscular girdle that surrounds the chiton's body. This arrangement allows chitons to roll into a protective ball when dislodged and to cling tightly to even irregular surfaces.

The girdle is often ornamented with spicules, bristles, hairy tufts, spikes, or snake-like scales. The majority of the body is a snail-like foot, but no head or other soft-parts beyond the girdle are visible from the dorsal side. The word snail is a Common name that can be used for almost all members of the Molluscan class Gastropoda which have coiled shells in the The foot is an Anatomical structure found in many Animals It is the terminal portion of a limb which bears weight and allows Locomotion.

The underside of the gumboot chiton, Cryptochiton stelleri, showing the foot in the center, surrounded by the gills and mantle. The mouth is visible above and to the left of the foot.
The underside of the gumboot chiton, Cryptochiton stelleri, showing the foot in the center, surrounded by the gills and mantle. The gumboot chiton, Cryptochiton stelleri, also known as the giant pacific chiton, is the largest of the Chitons growing to 33  cm (13 in The gumboot chiton, Cryptochiton stelleri, also known as the giant pacific chiton, is the largest of the Chitons growing to 33  cm (13 in A gill is an anatomical structure found in many aquatic organisms The mantle is an important part of the anatomy of Molluscs It is the dorsal body wall which covers the visceral mass The mouth is visible above and to the left of the foot.

Between the body and the girdle, there is a mantle cavity, connected to the outside by two water channels. The mantle is an important part of the anatomy of Molluscs It is the dorsal body wall which covers the visceral mass Water is a common Chemical substance that is essential for the survival of all known forms of Life. Physical geography, a channel is the physical confine of a River, slough or ocean Strait consisting of a bed and banks The one on the side is the incurrent water channel. The one attached to the anus is the excurrent water channel. The anus is an opening at the opposite end of an Animal 's Digestive tract from the Mouth. [1]

The gills hang down into the mantle cavity, usually near the anus. A gill is an anatomical structure found in many aquatic organisms An anterior head has a mouth containing a tongue-like structure called a radula, which has numerous rows of usually 17 teeth each. In Anatomy, the head of an Animal is the Rostral part (from Anatomical position that usually comprises the Brain, Eyes The mouth, buccal cavity, or oral cavity is the first portion of the Alimentary canal that receives food and begins digestion by mechanically breaking up The radula is a toothed Chitinous ribbon typically used for scraping cutting and chewing food before it enters the Esophagus. The teeth are coated with magnetite, a ferric/ferrous oxide mineral that hardens the teeth. Magnetite is not to be confused with Magnesite or Maghemite. Magnetite is a ferrimagnetic Mineral with chemical The radula is used to scrape microscopic algae off the substratum. Algae ( sing. alga are a large and diverse group of simple typically Autotrophic organisms ranging from Unicellular to Multicellular forms

Fossil ancestors of chitons

A possible Pre-Cambrian ancestor of chitons is Kimberella. The Precambrian ( Pre-Cambrian) is an informal name for the supereon comprising the eons of the Geologic timescale that came before the current Kimberella is a Genus of Fossils known only from rocks of the Ediacaran period and only one Species, Kimberella quadrata Chitons may also share a connection to Wiwaxia. See also Halwaxiida Wiwaxia is genus of soft-bodied scale-covered animals known from Burgess shale type dating from the Early to Middle Cambrian

History of the scientific investigation of chitons

Chitons were first studied by Carolus Linnaeus in 1758. Carl Linnaeus (Latinized as Carolus Linnaeus, also known after his ennoblement as, May 23 new style (13 May old style 1707 who laid the foundations for Since his description of the first four species, chitons have been variously classified. They were called Cyclobranchians ("round arm") in the early 19th century, and then grouped with the aplacophorans in the subphylum Amphineura in 1876. The 19th century of the Common Era began on January 1, 1801 and ended on December 31, 1900, according to the Gregorian calendar In life a subphylum is a Taxonomic rank intermediate between phylum and superclass. The class Polyplacophora was named by J. A class is the Taxonomic rank in the Biological classification of organisms in Biology below phylum and above order. E. Gray in 1821. Year 1821 ( MDCCCXXI) was a Common year starting on Monday (link will display the full calendar of the Gregorian Calendar (or a Common year

Taxonomy

Most classification schemes in use today are based, at least in part, on Pilsbry's Manual of Conchology (1892-1894), extended and revised by Kaas and Van Belle (1985-1990).

Since chitons were first described by Linnaeus (1758) there have been extensive taxonomic studies at the species level. However, the taxonomic classification at higher levels in the group has remained somewhat unsettled.

The most recent classification (Sirenko 2006) is based not only on shell morphology, as usual, but also other important features including aesthetes, girdle, radula, gills, glands, egg hull projections and spermatozoids. It includes all the living and extinct genera of chitons.

This system is now generally accepted.

References

  1. ^ TSN 78807. Henri Marie Ducrotay de Blainville ( September 12, 1777 - May 1, 1850) was a French Zoologist and Anatomist. Incertae sedis ( Latin for "of uncertain placement" abbreviated "inc Integrated Taxonomic Information System. Integrated Taxonomic Information System ( ITIS) is a partnership designed to provide consistent and reliable information on the Taxonomy of biological Species

External links

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