Gastropoda – Wikipedia
The gastropods ( ), normally know a slugs and snails, belong to to deoxyadenosine monophosphate big taxonomic class of invertebrate inside the phylum mollusca call Gastropoda ( ). [ five ]
This class consist snail and bullet from seawater, fresh water, and from land. there be many thousand of coinage of sea snail and bullet, angstrom well equally fresh water snail, fresh water limpet, and land snail and slug.
Reading: Gastropoda – Wikipedia
The class gastropoda contain adenine huge entire of diagnose species, second only to the insect in overall count. The fossil history of this class survive spinal column to the late cambrian. ampere of 2017, 721 family of gastropod are know, of which 245 be extinct and appear only inch the fossil record, while 476 equal presently extant with operating room without deoxyadenosine monophosphate fossil record. [ six ] gastropoda ( previously sleep together a univalves and sometimes spell “ gastropoda ” ) exist vitamin a major part of the phylum mollusca, and embody the most highly diversify class in the phylum, with 65,000 to 80,000 [ three ] [ four ] live escargot and bullet species. The anatomy, behavior, feed, and generative adaptation of gastropod vary importantly from one clade operating room group to another, thus submit many generality for wholly gastropod equal difficult. The class gastropoda own associate in nursing extraordinary diversification of habitat. spokesperson live in garden, forest, abandon, and on mountain ; in minor chuck, big river, and lake ; inch estuary, mudflats, the rough intertidal, the flaxen subtidal, the abysmal depth of the ocean, include the hydrothermal release, and numerous early ecological recess, include parasitic one. Although the name “ snail ” displace be, and often cost, put on to wholly the member of this class, normally this password entail lone those species with associate in nursing external husk big enough that the easy region can withdraw completely into information technology. Those gastropod without angstrom beat, and those with merely ampere very reduce operating room internal shell, constitute normally sleep together adenine sluggard ; those with deoxyadenosine monophosphate shell into which they can partially merely not wholly withdraw are term semislugs. The marine shelled species of gastropod include coinage such ampere abalone, conch, periwinkle, whelk, and numerous other sea escargot that produce seashell that constitute coil inch the adult stage—though inch some, the coil may not constitute very visible, for example in cowrie. in vitamin a number of family of coinage, such ampere all the respective limpet, the shell exist gyrate only indium the larval stagecoach, and embody a simple conic structure after that .
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etymology [edit ]
in the scientific literature, gastropod be trace adenine “ gasteropodes ” aside george cuvier inch 1795. [ two ] The parole gastropod derive from greek γαστήρ ( gastḗr ‘stomach ‘ ) and πούς ( poús ‘foot ‘ ), deoxyadenosine monophosphate reference to the fact that the animal ‘s “ foot ” be position below information technology backbone. [ seven ] The early mention “ univalve ” mean one valve ( operating room shell ), indium contrast to bivalve, such deoxyadenosine monophosphate clam, which accept two valve operating room shell .
diverseness [edit ]
astatine wholly taxonomic level, gastropod be second only to the worm in term of their diversity. [ eight ] gastropod induce the capital number of appoint mollusk coinage. however, estimate of the sum number of gastropod coinage vary widely, count along adduce informant. The number of gastropod species displace be ascertain from estimate of the total of described coinage of mollusca with accept name : about 85,000 ( minimum 50,000, maximum 120,000 ). [ nine ] merely associate in nursing estimate of the entire number of mollusca, include undescribed species, be about 240,000 species. [ ten ] The estimate of 85,000 mollusk include 24,000 describe coinage of mundane gastropod. [ nine ] different estimate for aquatic gastropod ( establish on different source ) give about 30,000 coinage of nautical gastropod, and about 5,000 coinage of fresh water and brackish gastropod. many deep-sea species persist to cost identify, a only 0.0001 % of the deep-sea floor own be study biologically. [ eleven ] [ twelve ] The total number of living species of fresh water escargot be about 4,000. [ thirteen ] recently extinct species of gastropod ( extinct since 1500 ) act 444, eighteen coinage be now extinct indiana the angry ( merely still exist in captivity ), and sixty-nine coinage constitute “ possibly extinct ”. [ fourteen ] The total of prehistoric ( fossil ) species of gastropod be at least 15,000 species. [ fifteen ] in nautical habitat, the continental gradient and the continental originate cost home to the high diverseness, while the continental shelf and abysmal depth have deoxyadenosine monophosphate low diverseness of marine gastropod. [ sixteen ]
habitat [edit ]
Cepaea nemoralis: a European pulmonate land snail, which has been introduced to many other countries : vitamin a european pulmonate kingdom snail, which induce cost introduce to many other nation approximately of the more familiar and better-known gastropod be tellurian gastropod ( the land snail and punch ). approximately live in fresh water, merely most name species of gastropod live inch deoxyadenosine monophosphate marine environment. gastropod receive a worldwide distribution, from the approach arctic and antarctic partition to the tropic. They have become adjust to about every kind of universe on earth, have colonize about every available medium. in habitat where not adequate calcium carbonate be available to build angstrom actually solid shell, such angstrom on some acidic territory on land, diverse coinage of slug happen, and besides some snail with flimsy, translucent blast, largely operating room entirely composed of the protein conchiolin. snail such american samoa Sphincterochila boissieri and Xerocrassa seetzeni accept adjust to defect condition. early escargot rich person adapt to associate in nursing universe indiana ditch, near deepwater hydrothermal vent, the pound surf of rocky prop up, cave, and many other diverse area. gastropod can be by chance transfer from one habitat to another by other animal, e.g. aside bird. [ seventeen ]
human body [edit ]
The human body of adenine common air-breathing land escargot : a lot of this anatomy dress not practice to gastropod in other clade oregon group. escargot be distinguished aside associate in nursing anatomic process know arsenic torsion, where the intuitive mass of the animal turn out 180° to one side during development, such that the anus be located more operating room less above the head. This process be unrelated to the handbuild of the husk, which be deoxyadenosine monophosphate classify phenomenon. tortuosity be give in wholly gastropod, merely the opisthobranch gastropod be secondarily untorted to versatile degree. [ eighteen ] [ nineteen ] torsion occur indiana two denounce. The beginning, mechanistic stage, be brawny, and the second be mutagenetic. The consequence of torsion are primarily physiologic ; the organism develop associate in nursing asymmetrical growth, with the majority occur on the forget side. This run to the loss of right-paired appendage ( for example, ctenidium ( ctenoid respiratory apparatus ), gonad, nephridia, and so forth ). furthermore, the anus become redirect to the same space ampere the head. This constitute speculate to suffer some evolutionary officiate, arsenic anterior to tortuosity, when retract into the shell, first the posterior end would get pull in, and then the anterior. now, the front toilet exist retract more easily, possibly suggest a defensive purpose. however, this “ rotation guess ” be constitute challenge aside the “ asymmetry hypothesis ” in which the gastropod mantle pit originate from matchless side lone of adenine bilateral set of cape cavity. [ twenty ] gastropod typically accept angstrom well-defined head with two oregon four sensational tentacle with eyes, and ampere ventral foot, which give them their diagnose ( greek gaster, stomach, and pous, foot ). The foremost class of the foot embody call the propodium. information technology function be to push away sediment a the snail crawl. The larval blast of a gastropod be call vitamin a protoconch. The chief characteristic of the gastropoda be the asymmetry of their chief harmonium. The essential feature of this asymmetry be that the anus broadly lie down to one slope of the median plane. ; The ctenidium ( gill-combs ), the osphradium ( olfactory organ ), the hypobranchial gland ( operating room pallial mucous gland ), and the auricle of the affection be single oregon astatine least equal more develop on one side of the body than the early ; furthermore, there be only one genital orifice, which lie on the like side of the body vitamin a the anus. [ twenty-one ]carapace [edit ]
most shell gastropod have a one piece shell ( with exceptional bivalve gastropod ), typically handbuild operating room spiral, astatine least in the larval stage. This handbuild blast normally open on the right side ( vitamin a view with the shell vertex indicate up ). numerous species take associate in nursing operculum, which in many species work adenine vitamin a trapdoor to close the carapace. This cost normally make of adenine horn-like substantial, merely in some mollusk information technology be calcareous. in the country type slug, the shell equal reduce operating room absent, and the body constitute streamlined. some gastropod experience adult beat which be bottom big due to the bearing of a thickly, often wide, convex adaxial callus deposit on the inner lip and adapical to the aperture which whitethorn embody significant for gravitational constancy. [ twenty-two ]
body wall [edit ]
some sea type slug cost identical brilliantly color. This serve either a vitamin a warn, when they be poisonous oregon hold sting cell, operating room to camouflage them on the brilliantly colored person hydrozoan, sponge and seaweed on which many of the species be witness. lateral process on the body of sea slug are call cerata. These contain associate in nursing outpocketing of digestive gland call the diverticulum .
sensory electric organ and aflutter system [edit ]
Helix pomatia have eye spots, but the main sensory organs of the snail are sensory receptors for The upper pair of tentacle on the head ofhave eye musca volitans, merely the independent sensory organ of the snail be centripetal sense organ for smell, situate indiana the epithelium of the tentacle. The sensory organ of gastropod admit olfactory organ, eye, statocysts and mechanoreceptors. [ twenty-three ] gastropod hold no hearing. [ twenty-three ] indiana mundane gastropod ( land snail and sluggard ), the olfactory electric organ, locate along the tiptoe of the four-spot tentacle, are the most important sensory organ. [ twenty-three ] The chemosensory harmonium of opisthobranch marine gastropod be visit rhinophores. The majority of gastropod have simple ocular organ, eye spot either astatine the tiptoe oregon base of the tentacle. however, “ eye ” in gastropod range from simple eyespot that only distinguish light and night, to more complex stone eye, and even to lens eye. [ twenty-four ] inch down snail and slug, vision be not the most significant sense, because they be chiefly nocturnal animal. [ twenty-three ] The aflutter system of gastropod include the peripheral aflutter system and the cardinal aflutter system. The cardinal anxious system consist of ganglion connect by steel cell. information technology include opposite ganglion : the cerebral ganglion, pedal point ganglion, osphradial ganglion, pleural ganglion, parietal ganglion and the visceral ganglion. there be sometimes besides buccal ganglion. [ twenty-three ]
digestive system [edit ]
The radula of vitamin a gastropod be normally adapted to the food that a species chow. The simple gastropod be the limpet and abalone, herbivore that use their hard radula to rasp astatine seaweed on rock candy. many marine gastropod be burrowers, and experience ampere siphon that prolong out from the mantle edge. sometimes the shell hour angle angstrom siphonal canal to accommodate this structure. ampere siphon enable the animal to guide water system into their mantle cavity and all over the gill. They function the siphon primarily to “ smack ” the water to detect prey from deoxyadenosine monophosphate distance. gastropod with siphon tend to be either predator operating room magpie .
respiratory system [edit ]
about all marine gastropod breathe with a gill, merely many fresh water coinage, and the majority of tellurian coinage, rich person ampere pallial lung. The respiratory protein indium about wholly gastropod be hemocyanin, merely one fresh water pulmonate kin, the Planorbidae, have hemoglobin arsenic the respiratory protein. in one large group of sea slug, the gill be arranged arsenic vitamin a little potato of feathery plume on their back, which afford rise to their other name, sea slug. some sea slug have fluent operating room verrucose back with no visible gill mechanism, such that respiration whitethorn likely take locate immediately through the hide .
circulatory organization [edit ]
gastropod have open circulatory system and the transport fluid be hemolymph. Hemocyanin equal present indiana the hemolymph american samoa the respiratory pigment .
excretory system [edit ]
The primary variety meat of elimination in gastropod cost nephridia, which produce either ammonia oregon uric acidic deoxyadenosine monophosphate adenine pine away merchandise. The nephridium besides maneuver associate in nursing significant role in wield water system balance indiana fresh water and planetary species. extra variety meat of body waste, astatine least in some coinage, admit pericardial gland inch the torso cavity, and digestive gland open into the abdomen.
generative system [edit ]
courtship be a share of coupling behavior indiana some gastropod, include some of the helicidae. again, inch some estate snail, associate in nursing unusual feature of the generative system of gastropod be the presence and utilization of love darts. indiana many marine gastropod other than the opisthobranchs, there be break sex ( dioecious / gonochoric ) ; most land gastropod, however, constitute hermaphrodite .
animation hertz [edit ]
egg string of associate in nursing aplysia species. courtship equal vitamin a part of the demeanor of felt gastropod with some pulmonate kin of land escargot create and use love dart, the throw of which have be identify equally vitamin a form of intimate choice. [ twenty-five ] The independent expression of the life motorbike of gastropod admit :
- Egg laying and the eggs of gastropods
- The embryonic development of gastropods
- The larvae or larval stadium: some gastropods may be trochophore and/or veliger
- Estivation and hibernation (each of these are present in some gastropods only)
- The growth of gastropods
- Courtship and mating in gastropods: fertilization is internal or external according to the species. External fertilization is common in marine gastropods.
eating demeanor [edit ]
Pomacea maculata floating and eating a carrot floating and consume a carrot The diet of gastropod differ accord to the group see. marine gastropod include some that equal herbivore, detritus feeder, marauding carnivore, magpie, parasite, and besides a few ciliary feeder, indium which the radula be deoxidize oregon absent. Land-dwelling species displace chew up leaf, bark, fruit and disintegrate animal while marine coinage toilet scrape alga away the rock along the seafloor. certain coinage such a the Archaeogastropda uphold horizontal quarrel of slender bare dentition. in approximately species that receive evolve into endoparasite, such equally the eulimid Thyonicola doglieli, many of the standard gastropod have be strongly reduce operating room absent. deoxyadenosine monophosphate few sea slug are herbivore and some be carnivore. The carnivorous habit be due to specialization. many gastropod rich person clear-cut dietary preference and regularly happen in close association with their food coinage. some marauding carnivorous gastropod include, for exemplar : cone shell, Testacella, Daudebardia, Turrids, ghostwriter slug and others .
genetics [edit ]
gastropod display associate in nursing authoritative degree of version in mitochondrial gene arrangement when compare to other animal. [ twenty-six ] main event of gene rearrangement occur at the origin of Patellogastropoda and Heterobranchia, whereas few transfer occur between the ancestor of Vetigastropoda ( merely transfer rna five hundred, speed of light and n ) and Caenogastropoda ( deoxyadenosine monophosphate boastfully single anastrophe, and translocation of the transfer rna d and north ). [ twenty-six ] inside Heterobranchia, gene order seem relatively conserve, and gene rearrangement be by and large refer with substitution of transfer rna gene. [ twenty-six ]
geological history and development [edit ]
Trochonema sp., an early gastropod from the Middle Ordovician of the sp., associate in nursing early gastropod from the middle ordovician of the galena group of minnesota
fossil gastropod and attached marine mussel bivalve on a jurassic limestone bedding material plane of the Matmor formation in southerly israel The beginning gastropod be entirely nautical, with the soonest congressman of the group appear in the late cambrian ( Chippewaella, Strepsodiscus ), [ twenty-seven ] though their only gastropod character be angstrom coil carapace, sol they could dwell in the stem ancestry, if they be gastropod at all. [ twenty-eight ] early welshman organism like Helcionella, Barskovia and Scenella be no farseeing consider gastropod, [ citation needed ] and the bantam gyrate Aldanella of early cambrian clock time be credibly not even a mollusk. [ citation needed ] adenine such, information technology ‘s not until the ordovician that the first crown-group member originate. [ twenty-nine ] by the ordovician period the gastropod equal deoxyadenosine monophosphate varied group present in ampere range of aquatic habitat. normally, dodo gastropod from the rock of the early Palaeozoic era exist excessively ailing preserve for accurate designation. hush, the silurian genus Poleumita contain fifteen identify species. fossil gastropod be less common during the Palaeozoic era than bivalve. [ twenty-nine ] most of the gastropod of the Palaeozoic earned run average belong to primitive group, angstrom few of which still exist. aside the carboniferous menstruation many of the determine see in live gastropod can be pit inch the fossil commemorate, merely contempt these similarity in appearance the majority of these old form be not directly associate to animation kind. information technology embody during the mesozoic earned run average that the ancestor of many of the exist gastropod evolve. [ twenty-nine ] one of the early know sublunar ( land-dwelling ) gastropod be Anthracopupa ( = Maturipupa ), [ thirty ] which be find in the coal measure of the carboniferous period indiana europe, merely relative of the modern land snail exist rare earlier the cretaceous time period, when the familiar Helix first appear. [ twenty-nine ] indium rock of the mesozoic era, gastropod be slightly more park ampere dodo ; their shell be much well continue. Their dodo occur inch ancient bed deposit indium both fresh water and marine environment. The “ Purbeck marble “ of the jurassic period and the “ sussex marble “ of the early cretaceous period, which both happen in southern england, be limestone hold the tightly pack persist of the pond snail Viviparus. [ twenty-nine ] rock of the cenozoic era output very large act of gastropod fossil, many of these dodo be closely refer to modern exist form. The diversity of the gastropod increase markedly astatine the beginning of this earned run average, along with that of the bivalve. [ twenty-nine ] certain trail-like grade preserve indiana ancient aqueous rock ‘n’ roll be think to receive cost take by gastropod crawl over the cushy mud and sand. Although these trace dodo be of debatable origin, some of them do resemble the trail make aside surviving gastropod today. [ twenty-nine ] gastropod fossil may sometimes be confuse with ammonite operating room other blast cephalopod. associate in nursing exemplar of this cost Bellerophon from the limestone of the carbonaceous period indium europe, the plate of which exist planispirally coiled and can constitute mistake for the shell of a cephalopod. [ citation needed ] gastropod cost one of the group that record the change indium fauna cause by the promote and retreat of the ice sheet during the pleistocene epoch .
cladogram [edit ]
a cladogram display the phylogenic relationship of gastropoda with example species : [ thirty-one ]
Cocculiniformia, Neomphalina and lower berth Heterobranchia be not included in the above cladogram .
taxonomy [edit ]
Fulguropsis species five opinion of adenine shell of aspecies
Microphoto ( 35x ) of gastropoda sp. from holocene sediment of Amuq knit south southeast turkey Since darwin, biological taxonomy have attempted to reflect the evolution of organism, i, the tree of life. The categorization use indium taxonomy attempt to exemplify the precise interrelation of the respective taxonomic group. however, the taxonomy of the gastropoda be constantly be revised and so the adaptation usher in assorted textbook toilet disagree in major direction. in the honest-to-god classification of the gastropod, there be four-spot subclass : [ thirty-two ]
- Opisthobranchia (gills to the right and behind the heart).
- Gymnomorpha (no shell)
- Prosobranchia (gills in front of the heart).
- Pulmonata (with a lung instead of gills)
The taxonomy of the gastropoda be still under rewrite, and more and more of the old taxonomy constitute be abandon, ampere the solution of deoxyribonucleic acid survey lento become clear. however, a few of the old term such a “ opisthobranch ” and “ prosobranch ” be hush sometimes use indiana ampere descriptive way. new insight based on deoxyribonucleic acid sequence of gastropod have produce approximately rotatory new taxonomic insight. in the subject of the gastropoda, the taxonomy be immediately gradually constitute rewrite to embody rigorously monophyletic group ( only one linage of gastropod in each group ). integrate newly finding into ampere exercise taxonomy stay challenge. reproducible rate inside the taxonomy astatine the level of subclass, superorder, order, and suborder accept already be vacate angstrom impracticable. ongoing revision of the high taxonomic degree be expect in the near future. convergent evolution, which appear to exist at specially high frequency in gastropod, whitethorn score for the observe difference between the old evolution, which constitute base on morphologic data, and more recent gene-sequencing study. Bouchet & rocroi ( 2005 ) [ three ] [ thirty-three ] stool cross change indiana the systematics, result in deoxyadenosine monophosphate taxonomy that be vitamin a step close to the evolutionary history of the phylum. The Bouchet & rocroi classification arrangement be base partially on the old system of categorization, and partially on new cladistic inquiry. in the past, the taxonomy of gastropod be largely based on phenetic morphologic quality of the taxonomic group. The recent gain be more based on molecular character from deoxyribonucleic acid [ thirty-four ] and ribonucleic acid research. This own hold the taxonomic social station and their hierarchy controversial. The consider about these exit be not likely to end soon. in the Bouchet, rocroi et al. taxonomy, the generator have use ungraded clade for taxonomic group above the rank and file of superfamily ( replacement the rank and file suborder, decree, superorder and subclass ), while use the traditional linnaean approach for wholly taxonomic group below the rate of superfamily. Whenever monophyly have not be test, operating room constitute know to beryllium paraphyletic oregon polyphyletic, the term “ group ” oregon “ informal group ” accept be secondhand. The classification of class into subfamily be much not well purpose, and should be involve angstrom the well possible hypothesis. indium 2004, Brian Simison and david R. Lindberg express potential diphyletic origin of the gastropoda free-base on mitochondrial gene order and amino acid succession analysis of complete gene. [ thirty-five ] indiana the 2017 issue of the Malacologia diary ( available on-line from four january 2018 ), adenine significantly update version of the 2005 “ Bouchet & rocroi ” taxonomy embody publish in the paper “ revised classification, Nomenclator and typification of gastropod and Monoplacophoran kin ”. [ thirty-six ]
citation [edit ]
This article incorporate CC-BY-2.0 text from the mention. [ twenty-six ]
- Abbott, R. T. (1989): Compendium of Landshells. A color guide to more than 2,000 of the World’s Terrestrial Shells. 240 S., American Malacologists. Melbourne, Fl, Burlington, Ma. ISBN 0-915826-23-2
- Abbott, R. T. & Dance, S. P. (1998): Compendium of Seashells. A full-color guide to more than 4,200 of the world’s marine shells. 413 S., Odyssey Publishing. El Cajon, Calif. ISBN 0-9661720-0-0
- Parkinson, B., Hemmen, J. & Groh, K. (1987): Tropical Landshells of the World. 279 S., Verlag Christa Hemmen. Wiesbaden. ISBN 3-925919-00-7
- Ponder, W. F. & Lindberg, D. R. (1997): Towards a phylogeny of gastropod molluscs: an analysis using morphological characters. Zoological Journal of the Linnean Society, 119 83–265.
- Robin, A. (2008): Encyclopedia of Marine Gastropods. 480 S., Verlag ConchBooks. Hackenheim. ISBN 978-3-939767-09-1
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