Protoconch

An SEM image of the trochophore of Haliotis asinina 11 hours post fertilization, with calcified protoconch (pc) prior to torsion.
Protoconch of Haliotis asinina when the torsion is complete.

A protoconch (meaning first or earliest or original shell) is an embryonic or larval shell which occurs in some classes of molluscs, e.g., the initial chamber of an ammonite or the larval shell of a gastropod. In older texts it is also called "nucleus". The protoconch may sometimes consist of several whorls, but when this is the case, the whorls show no growth lines.

The whorls of the adult shell, which are formed after the protoconch, are known as the teleoconch. The teleoconch starts forming when the larval gastropod becomes a juvenile, and the protoconch may dissolve. Quite often there is a visible line of demarcation where the protoconch ends and the teleoconch begins, and there may be a noticeable change in sculpture, or a sudden appearance of sculpture at that point.

In some gastropod groups (such as the Architectonicidae), the teleoconch whorls spiral in the opposite direction to the protoconch. In those cases, the shell is called heterostrophic.

In species which have a veliger or swimming larval stage which hatches out of egg capsules, there are two parts to the protoconch. The first part of the protoconch (which is formed within the embryonic egg capsule) is called protoconch 1, while the part that is formed after the larva has hatched is called protoconch 2. There is often a different sculpture or ornamentation on protoconch 1 compared with protoconch 2, and this can be distinguished under the microscope.

The structure of the protoconch has been widely used as a discriminating feature in gastropod systematics. For example, certain nudibranches have an 'inflated' protoconch, which does not grow but houses the growing soft tissues of the larva, and this distinguishes them from other gastropods.[1]

The homologous structure in bivalves (clams) is called the prodissoconch.

Examples

Comparison of the whole shell and the protoconch of Atlanta lesueurii:

Apical view of the whole shell.
Detail of apical view of the same shell showing clearly visible protoconch, that has 2¼ whorls
Growth series of Caecum glabrum showing protoconch in bottom image.

References

  1. ^ Page, Louise (2000). "Inflated Protoconchs and Internally Dissolved, Coiled Protoconchs of Nudibranch Larvae: Different Developmental Trajectories Achieve the Same Morphological Result". Invertebrate Biology. 119 (3): 278–286. doi:10.1111/j.1744-7410.2000.tb00014.x. JSTOR 3227175. Retrieved 20 November 2020.

Read other articles:

Union City (California)

Union CityKotaStasiun Union City Bay Area Rapid Transit (BART)Lokasinya di Alameda County dan negara bagian CaliforniaKoordinat: 37°35′47″N 122°02′54″W / 37.59639°N 122.04833°W / 37.59639; -122.04833Koordinat: 37°35′47″N 122°02′54″W / 37.59639°N 122.04833°W / 37.59639; -122.04833Negara Amerika SerikatNegara bagian CaliforniaCounty AlamedaTergabung26 Januari 1959[1]Pemerintahan • Wali kotaCarol Dutra-Ve...

 

The 13th Scroll

1999 studio album by Cobra StrikeThe 13th ScrollStudio album by Cobra StrikeReleasedAugust 24, 1999 2010 (reissue)Recorded1999 (1999) at Moseleum Tunnel, Chatsworth, CaliforniaGenreAvant-garde metal, electronicaLength52:34LabelIonProducerTravis Dickerson, Buckethead, Jerry ManoCobra Strike chronology The 13th Scroll(1999) Cobra Strike II: Y, Y+B, X+Y <hold> ←(2000) Professional ratingsReview scoresSourceRatingPitchfork Media(7.0/10) [1] The 13th Scroll is the firs...

 

Ayam kedu

Ayam keduAyam kedu betina berwarna hitamNama lainAyam cemaniAyam selasihNegara asalIndonesiaKarakteristikBeratJantan: 2-2,5 kg Betina: 1,5-2 kgWarna kulitHitamWarna telurCreamKlasifikasi Ayam kedu, ayam selasih, atau ayam cemani adalah ras ayam lokal yang telah dikembangkan di di Pulau Jawa sejak abad ke-12. Ayam cemani memiliki gen dominan yang menyebabkan hiperpigmentasi (fibromelanosis), yang membuat ayam-ayam ini kebanyakan berwarna hitam, termasuk bulu, paruh, dan organ da...

Dwi Suharjo

Dwi Suharjo Kepala Staf Korem 132/TadulakoMasa jabatan8 Juni 2020 – 22 September 2022 PenggantiBambang Pranowo Informasi pribadiLahir0 Oktober 1968 (umur 55)IndonesiaKebangsaan IndonesiaAlma materAkademi Militer (1992)Karier militerPihak IndonesiaDinas/cabang TNI Angkatan DaratMasa dinas1992—sekarangPangkat KolonelNRP1920025251068SatuanInfanteriPertempuran/perangOperasi TinombalaSunting kotak info • L • B Kolonel Inf. Dwi Suharjo, S.I.P. (lahir O...

 

Mass Effect

Science fiction media franchise This article is about the video game series. For the medical effect, see Mass effect (medicine). Video game seriesMass EffectLogo since 2017Genre(s) Science fiction Military science fiction Space opera Action role-playing Developer(s) BioWare Edge of Reality Demiurge Studios Straight Right Publisher(s) Microsoft Game Studios (2007–11) Electronic Arts (2010–present) Creator(s)Casey HudsonPlatform(s) Xbox 360 Microsoft Windows iOS PlayStation 3 Android Window...

 

Regensburg

Regensburg Lambang kebesaranLetak Regensburg NegaraJermanNegara bagianBayernWilayahUpper PalatinateKreisDistrik urbanSubdivisions18 distrikPemerintahan • Lord MayorJoachim Wolbergs (SPD)Luas • Total80,76 km2 (3,118 sq mi)Ketinggian tertinggi471 m (1,545 ft)Ketinggian terendah326 m (1,070 ft)Populasi (2013-12-31)[1] • Total140.276 • Kepadatan17/km2 (45/sq mi)Zona waktuWET/WMPET (UTC+1...

Mettawa, Illinois

Village in Illinois, United StatesMettawa, IllinoisVillageLocation of Mettawa in Lake County, Illinois.Location of Illinois in the United StatesCoordinates: 42°14′38″N 87°55′4″W / 42.24389°N 87.91778°W / 42.24389; -87.91778CountryUnited StatesStateIllinoisCountyLakeGovernment • MayorCasey UrlacherArea[1] • Total5.53 sq mi (14.32 km2) • Land5.45 sq mi (14.12 km2) • Water0....

 

Temple Hill (Hong Kong)

Hill between New Kowloon and the New Territories, Hong Kong For the residential area in New Kowloon, see Tsz Wan Shan. Temple Hill慈雲山View of Temple HillHighest pointElevation488 m (1,601 ft)Coordinates22°21′22″N 114°12′24″E / 22.356094°N 114.206572°E / 22.356094; 114.206572GeographyTemple HillLocation of Temple Hill in Hong Kong Location Hong Kong Temple Hill, also known as Tsz Wan Shan (Chinese: 慈雲山), is a hill between N...

 

Hantu Jeruk Purut

Hantu Jeruk Purut fiksiSutradaraKoya PagayoProduserShankar RSSkenarioEry SofidPemeranAngieSheila MarciaSamuel ZylgwynValia RahmaRenny UmariYulia WidyastutiFerry IrawanPenata musikEric DewantoroSinematograferDharma YouPenyuntingAziz NatandraPerusahaanproduksiIndika EntertainmentTanggal rilis30 November 2006Durasi90 menitNegaraIndonesiaBahasaBahasa Indonesia Hantu Jeruk Purut adalah film horor Indonesia yang dirilis pada tahun 2006. Film yang disutradarai oleh Koya Pagayo ini dibintangi o...

Sainte-Honorine-des-Pertes

Sainte-Honorine-des-PertesfrazioneSainte-Honorine-des-Pertes – Veduta LocalizzazioneStato Francia Regione Normandia Dipartimento Calvados ArrondissementBayeux CantoneTrévières ComuneAure sur Mer TerritorioCoordinate49°21′N 0°48′W / 49.35°N 0.8°W49.35; -0.8 (Sainte-Honorine-des-Pertes)Coordinate: 49°21′N 0°48′W / 49.35°N 0.8°W49.35; -0.8 (Sainte-Honorine-des-Pertes) Superficie5,67 km² Abitanti604[1] (2009) Dens...

 

وسام الاستحقاق اللبناني

وسام الاستحقاق اللبناني رتبة الوشاح الأكبر مؤسس لبنان  البلد لبنان  يُمنح من طرف  لبنان نوع الوسام وسام استحقاق المراتب 5 درجات إحصاءات تاريخ الإنشاء 16 يناير 1922  صورة شريط الوسام   تعديل مصدري - تعديل   وسام الاستحقاق هو وسام استحقاق لبنان أنشئ في 16 يناير 1922. ا...

 

Delisa Walton-Floyd

American middle-distance runner Delisa Walton-FloydPersonal informationNationalityAmericanBorn (1961-07-28) July 28, 1961 (age 62)SportCountry United StatesSportTrackEvent800 mCollege teamTennesseeClubSanta Monica Track Club Medal record Representing  United States Women's Athletics Pan American Games Indianapolis 1987 800 Meters Delisa Walton-Floyd (born Delisa Walton, 28 July 1961) is a former World-Class middle distance runner who specialized in the 800 metres; she was a two...

Republic (Plato)

Philosophical work by Plato around 375 BC This article possibly contains original research. Please improve it by verifying the claims made and adding inline citations. Statements consisting only of original research should be removed. (April 2022) (Learn how and when to remove this message) Republic Title page of the oldest complete manuscript: Paris, Bibliothèque Nationale, Gr. 1807 (late 9th century)AuthorPlatoOriginal titleΠολιτείαCountryAncient GreeceLanguageGreekSubjectPoli...

 

Laut Kreta

Laut Kreta. Laut Kreta terletak di utara pulau Kreta, dan di selatan Aegea. Laut Kreta (Yunani: Κρητικό Πέλαγος, Kritiko Pelagos) adalah laut di selatan Laut Aegea, utara pulau Kreta, dan selatan Cyclades.[1] Laut juga membentang dari Kythera timur ke pulau-pulau Dodecanese dari Karpathos dan Kassos. Laut berada ke barat adalah Laut Ionia serta sisa Laut Mediterania. Rute feri dari ke dan Iraeus, serta pulau-pulau selatan Aegean dan Dodecanese, dijalankan di daerah ini. ...

 

Islam in Mexico

Religion in Mexico Muslims in Tijuana Islam by countryWorld percentage of Muslims by country Africa Algeria Angola Benin Botswana Burkina Faso Burundi Cameroon Cape Verde Central African Republic Chad Comoros Democratic Republic of the Congo Republic of the Congo Djibouti Egypt Equatorial Guinea Eritrea Eswatini Ethiopia Gabon Gambia Ghana Guinea Guinea-Bissau Ivory Coast Kenya Lesotho Liberia Libya Madagascar Malawi Mali Mauritania Mauritius Mayotte Morocco Western Sahara Mozambique Namibia ...

State Intelligence Agency (Bulgaria)

The State Intelligence Agency (SIA) (Bulgarian: Държавна агенция Разузнаване, romanized: Dǎržavna Agencija Razuznavane) is a Bulgarian foreign intelligence service, which obtains, processes, analyzes and provides the state leadership with intelligence, assessments, analyses and prognoses, related to the national security, interests and priorities of the Republic of Bulgaria.[1] Seal of The State Intelligence Agency History The history of intelligence a...

 

Eyespot (mimicry)

Eye-like marking used for mimicry or distraction Many butterflies, such as this gladeye bushbrown (Mycalesis patnia), have eyespots on their wings. An eyespot (sometimes ocellus) is an eye-like marking. They are found in butterflies, reptiles, cats, birds and fish. Eyespots could be explained in at least three different ways. They may be a form of mimicry in which a spot on the body of an animal resembles an eye of a different animal, to deceive potential predator or prey species. They may b...

 

Side platform

Railway platform with tracks along only one edge Side platforms with a pedestrian bridge between them A side platform (also known as a marginal platform[1] or a single-face platform) is a platform positioned to the side of one or more railway tracks or guideways at a railway station, tram stop, or transitway.[2] A station having dual side platforms, one for each direction of travel, is the basic design used for double-track railway lines (as opposed to, for instance, the islan...

Tepecoacuilco de Trujano

Questa voce o sezione sull'argomento centri abitati del Messico non cita le fonti necessarie o quelle presenti sono insufficienti. Puoi migliorare questa voce aggiungendo citazioni da fonti attendibili secondo le linee guida sull'uso delle fonti. Questa voce sull'argomento centri abitati del Guerrero è solo un abbozzo. Contribuisci a migliorarla secondo le convenzioni di Wikipedia. Tepecoacuilco de TrujanolocalitàLocalizzazioneStato Messico Stato federato Guerrero Comune...

 

Духовник

Грузинский православный священник, Мцхета Духовни́к — священник, которому человек исповедуется регулярно. У духовника православный христианин регулярно исповедуется, являясь по отношению к нему «духовным чадом». Духовник не только руководит духовной жизнью чада, у...