Daga cikin mafi dadaddun halittun da muke samu a gindin tekuna muna da cnidariansRuwa ne wanda aka hada da shi halittun ruwa Kuma sunanta ya fito daga wasu sifofin halayensa. Ana kiran su cndocytes Kuma waɗannan su ne suka sa waɗannan nau'ikan na musamman. A halin yanzu, a kusa 11.000 nau'in cnidarians wanda ya kasu kashi daban-daban, nau’o’i da nau’o’in halittu, an rarraba su a cikin kusan dukkan tekunan duniya da wasu ruwayen ruwa.
A cikin wannan labarin za mu gaya muku daki-daki game da fasali, mazaunin zama, azuzuwan, ciyar, rayuwa sake zagayowar y haifuwa na cnidarians, har ila yau, haɗa bayanai na ci-gaba da ilimin halitta da na halitta don fahimtar yadda waɗannan dabbobi suke da kuma yadda suke rayuwa.
Babban halayen 'yan cnidarians
Daga cikin dukkan nau'o'in da ke cikin wannan rukunin dabbobin da muke samu murjani, jellyfish, teku anemones, hydras kuma iri-iri mulkin mallakaA cikin cnidarians mun sami manyan jellyfish daga ko'ina cikin duniya. Wadannan galibi nau'in nau'in ruwa ne, kodayake wasu sun sami damar mamaye muhallin ruwa mai dadi, kamar wasu hydras da jellyfish daga manyan tafkuna.
Yawanci suna benthic da sessileWannan yana nufin sun taƙaita motsi kuma sun kasance a tsaye ga maƙasudin (alal misali na anemones da murjani). Sauran nau'in sun fi ƙanƙanta kuma ana la'akari da su planktonicyana iyo da yin iyo a cikin ginshiƙin ruwa. Girman waɗannan dabbobin ya bambanta daga ƙananan sifofi na ƴan milimita zuwa ƙaton kifin na fiye da haka Tsawon mita 20 ciki har da tanti.
Son kwayoyin diploblasticWato suna tasowa daga nau'ikan amfrayo guda biyu: da ectoderm (wanda ke haifar da epidermis ko ectodermis) da kuma endoderm (wanda ke haifar da gastrodermis). Tsakanin biyu ya ta'allaka ne da gelatinous Layer kira mesogleahaɓaka sosai a cikin jellyfish kuma mafi kyau a yawancin polyps. Godiya ga wannan ƙungiyar, cnidarians suna nuna a matakin kungiyar namaSuna da kyallen takarda amma ba su da hadaddun gabobin kamar zuciya, huhu, kodan, ko tsakiyar tsakiya.
Yawancin cnidarians suna da radial symmetryWato jikinsu an tsara shi ne a kusa da axis na baka na tsakiya. A wasu rukunoni wannan alamar za ta iya don canzawa zuwa biradial ko tetraradial symmetry, kamar yadda yake faruwa a yawancin jellyfish, inda za'a iya raba jiki zuwa hudu kwatanci daidai ko zuwa sassa shida ko takwas da aka maimaita.
Abin da ya fi fice game da cnidarians shine tantanin halitta shi ya sa suke samun wannan suna: da cnidocyteWaɗannan sel sun keɓanta ga phylum Cnidaria kuma sun ƙunshi fasalin binciken sa.
Cnidocytes: "makamin sirri" na cnidarians
da cndocytes ne Kwayoyin iya harba filament mai tsauri waje. A ciki suna dauke da capsule mai suna cin o nematocystinda aka ajiye filament mai naɗe. Lokacin da cnidocyte ya sami abin motsa jiki ko na sinadarai (misali, taɓa ganima), ƙaramin operculum yana buɗewa kuma ana harbi filament da sauri, huda ko kama wanda aka azabtar kuma a sake shi. abubuwa masu guba, m, ko haɗa abubuwa.
Wadannan cnidocytes sun fi mayar da hankali a cikin tentacles kuma a kusa da baki, amma kuma suna iya bayyana a warwatse ko'ina cikin epidermis da gastrodermis. Fitowar tana da saurin gaske, akan tsari na millise seconds, kuma a wasu nau'in gubar tana da ƙarfi sosai ta yadda zai iya shafar manyan kashin baya, gami da mutane.
The cnidarians Ba su da na'urori na musamman na excretory, na numfashi, da tsarin jini.Duk waɗannan ayyuka ana yin su ta hanyar gastrovascular cavity da gangar jikin. Canjin iskar gas (oxygen da carbon dioxide) yana faruwa ta hanyar watsa shirye-shirye kai tsaye ta sel yadudduka wanka da ruwa.
Ƙungiyar jiki da kuma gastrovascular cavity
Jikin cnidarians yayi kama da gashiSuna da rami guda ɗaya da ake kira gastrovascular cavity o coelenterowanda ke sadarwa tare da waje ta hanyar buɗewa guda ɗaya wanda ke aiki a lokaci ɗaya kamar baki da duburaWannan rami yana yin ayyuka da yawa a lokaci guda:
- Narkewa abinci ta hanyar enzymes da ke ɓoye ta gastrodermis.
- Rarraba kayan abinci da iskar oxygen zuwa sel na jiki.
- zubarwa zuwa waje ta bude baki daya.
- A lokuta yana aiki kamar hydrostatic skeleton, lokacin da aka cika da ruwa kuma ana amfani dashi azaman tallafi.
da tentacles An jera su a baki kuma yawan su yana cikin yawan 6 ko 8Dangane da ƙungiyar (musamman bayyananne a cikin anthozoans), waɗannan ginshiƙan suna da sassauƙa, kwangila, da wadata a cikin cnidocytes, suna ba su damar kama ganima, kare kansu, kuma a wasu lokuta, tafiya a cikin iyakataccen hanya.
Kasancewar kwayoyin halitta na farko, cnidarians Ba sa nuna cephalizationWato ba su da bambancin kai ko tsarin juyayi na tsakiya. tsarin juyayi Yana da sauki cibiyar sadarwa na neurons (jijiya plexus) rarraba a ko'ina cikin ectodermis kuma, zuwa wani karami, gastrodermis. Duk da haka, ƙungiyoyi da yawa suna haɓaka kwayoyin halitta da sassa masu sauƙi irin su statocysts (don ma'auni) da ocelli (don gano haske da inuwa).
Siffofin jiki: polyp da jellyfish
Babban tsarin jikin da aka samu a cikin wannan phylum sune: siffar polyp da hanyar medusaDukansu suna raba ƙungiya ta asali guda ɗaya (kogon gastrovascular, tentcles da baki) amma sun karkata zuwa baya kuma sun dace da salon rayuwa daban-daban.
- Polyp: hanya ce sessileAn gyara shi zuwa substrate. Yana da tsari silindatare da maƙala ƙarshen ɓarna (ta hanyar fayafai ko tushe) zuwa duwatsu, harsashi, ko laka, da ƙarshen baka yana nunawa sama tare da bakin kewaye da tanti. Yana iya zama m (anemones) ko siffa mulkin mallaka (yawancin murjani da hydrozoans).
- Medusa: hanya ce wayar hannu ko pelagic. Yana da siffar kararrawa ko laima (laima), tare da saman zubar da ciki sama da kuma bakin yana fuskantar ƙasa a tsakiyar gunkin, sau da yawa yana tsawaita zuwa maɓallin rikewaTanti suna rataye daga gefen laima. Motsin su yana dogara ne akan ƙwanƙwasa laima da ke motsa ruwa.
A yawancin nau'ikan akwai polymorphism Muhimmi: a cikin mallaka ɗaya za a iya samun daidaikun mutane da suka ƙware a ciyarwa, tsaro ko haifuwa (ciyarwa, kariya da zooids na haihuwa).
Rabawa na cnidarians
Yawancin nau'ikan cnidarians suna samarwa mulkin mallaka wanda ya ƙunshi kwayoyin halitta guda ɗaya da aka sani da zooidswanda zai iya zama kamar polyp, medusa-like, ko matsakaicin siffofin. Daga cikin manyan nau'ikan da ake amfani da su don rarraba cnidarians akwai wasu waɗanda Suna iya haifuwa ta hanyar jima'i ta hanyar polyps da sauransu a cikin a jima'i da jellyfishKuma a yawancin lokuta duka hanyoyin biyu suna canzawa a cikin tsarin rayuwa iri ɗaya.
Wasu nau'ikan na iya wucewa sau da yawa lokaci na polyp zuwa lokacin medusa yayin zagayowar rayuwarsu, yayin da wasu ke nuna matakin polyp kawai ko kuma matakin medusa kawai. A matakin haraji, phylum Cnidaria ya kasu kashi-kashi da yawa, amma don dalilai na yada aiki, ana amfani da manyan azuzuwan gargajiya guda huɗu: Anthozoa, Cubozoa, Hydrozoa da ScyphozoaBugu da kari, akwai wasu kungiyoyi irin su Staurozoa da cnidarians kamuwa da cuta (Myxozoa da Polypodiozoa), wanda ke kara fadada bambancinsu.
Anthozoa
Wannan ajin ya ƙunshi duk dabbobin da aka sani da anemones, murjani y gashin gashin tekuA cikin Anthozoa kawai polyp lokaciBabu wani tsari na medusa mai zaman kansa. Wadannan polyps na iya zama kadaici (manyan anemones) ko siffa m mazauna ( Murjani masu gina reef).
Polyp na iya haifar da duka biyu mai haila (budding, fragmentation) kamar yadda jima'ihaifar da sababbin polyps. Waɗannan dabbobin gaba ɗaya ne sessile kuma dole ne ya kasance a haɗe zuwa madaidaicin ta hanyar faifan fedar su ko tsarin daidai. tentacles wadanda ke cikin wadannan dabbobi ana samun su a ciki yawan 6 (Hexacorallia) ko 8 (Octocorallia), wanda ake amfani da shi azaman ma'aunin rarrabuwa na ciki.
Kogon ciki na ciki shine raba ta partitions ko mesenteries wanda ke ƙara yawan sararin samaniya don narkewa da sha. Wadannan septa sun samo asali ne daga gastrodermis kuma suna aiki a cikin mesoglea, suna samar da ɗakunan ciki. Yawancin anthozoans, musamman murjani masu duwatsu, suna ɓoyewa waje kwarangwal na calcium carbonate wanda, tara a kan tsararraki, ya haifar da shahararrun Girman murjani kuma su ne batun karatu a ciki akwatin ruwa na ruwa.
Kubozoa
Cubozoa kungiyoyin akwatin jellyfish da kuma bakin tekuWaɗannan nau'ikan suna da ɗaya kawai lokaci jellyfish da kyau ci gaba, yayin da polyp lokaci ne ƙanana da ɗan gajeren lokaciJellyfish yana da siffar sifa mai siffar sukari, daga wanda sunansa ya fito: laima yana da fuska hudu tare da gefuna masu kyau.
Gefen jellyfish ɗin nan yana ninkawa ciki don samar da tsari mai kama da mayafi, wanda ake kira alfarwawanda ke inganta ingancin motsa jiki. Ana saka ɗaya ko fiye a cikin sasanninta na laima. m tentacles akan wani faffadan gindi da ake kira fedaBugu da ƙari kuma, sun mallaki hadaddun sassan jiki (rhopallium) tare da ingantaccen ci gaban ocelli wanda ke ba su damar daidaita kansu a cikin ginshiƙi na ruwa.
Waɗannan dabbobin sun shahara don samun a mai guba sosai wanda zai iya zama kisa ga mutane A wasu nau'ikan, suna haifar da zafi mai tsanani, cututtukan zuciya da na numfashi. Saboda wannan dalili, akwatin jellyfish ana la'akari da wasu daga cikin mafi yawan dabbobi masu guba a cikin duniyar ruwa.
Hydrozoa
Wannan rukuni na dabbobi da aka fi sani da hydrojellyfish kuma ya haɗa da yawa hydropolypsA yawancin waɗannan nau'ikan akwai a canji na tsararraki tsakanin lokaci na polyp mai haila da lokacin jellyfish jima'i.
Yawancin lokaci ana tsara tsarin polyp cikin mulkin mallaka na mutane polymorphicWannan yana nufin cewa a cikin mulkin mallaka ɗaya akwai daidaikun mutane daban-daban siffofi da ayyukaWasu sun kware wajen ciyarwa, wasu kan tsaro, wasu kuma wajen haifuwa. Wannan polymorphism yana ƙyale yankunan mallaka suyi aiki kusan kamar superorganism mai inganci sosai.
Jellyfish na wannan nau'in yana da a velo (saboda haka sunan craspedota jellyfish) kama da velarium na akwatin jellyfish, kodayake na asali da tsari daban-daban. Ba su da cnidocytes a cikin kogon gastrovascular da su gonads suna da asalin ectodermalBa kamar scyphozoans da anthozoans ba, ba su da rami na gastrovascular da aka raba ta cikin septa na ciki.
Scyphozoa
A cikin wannan rukuni na dabbobi Tsarin jellyfish ya fi rinjaye a filila'akari da "real jellyfish"Matsayinsa na polyp (scyphopolyp ko scyphistoma) kadan ne kuma sau da yawa ba a gane shi ba. Scyphomedusae yawanci ya fi girma cewa hydromedusae, kuma a wasu nau'in laima na iya kaiwa fiye da mita daya a diamita.
Lokacin da suka isa matakin jellyfish ba su gabatar da wani mayafi baShi ya sa ake kiran su jellyfish acraspedotasamma sun mallaki hankali rhopali da cnidocytes a cikin cavity na gastrovascular. Ba kamar ajin Hydrozoa ba, wannan ajin na cnidarians yana da wani ɓangaren haɓakar rami na gastrovascular. raba ta hudu da bai cika partitions ko septa a cikin interradial matsayi, raba rami a cikin jakunkuna na ciki huduWannan ƙungiya ta cikin gida tana ƙarfafa ta tetraradial symmetry.
Sauran kungiyoyin cnidarians
Duk da cewa azuzuwan nan hudu da aka ambata a sama sune aka fi saninsu, rabe-rabe na cnidarians na yanzu ya hada da:
- Staurozoa: sessile, jellyfish mai siffa-kofi wanda aka haɗe zuwa maƙalar ta wani tsintsin tsiro. Suna wakiltar matsakaicin siffofi tsakanin polyps da medusae.
- Myxozoa: cnidarians microscopic parasites de peces da sauran kashin bayan ruwa, wanda aka dade ana la'akari da su protozoa.
- Polypodiozoa: cnidarians parasitic waɗanda ke zaune a cikin sel na wasu dabbobi, tare da keɓaɓɓun yanayin rayuwa.
Waɗannan ƙungiyoyin sun nuna cewa phylum Cnidaria ba wai kawai ya haɗa da jellyfish mai ban sha'awa da murjani masu ban mamaki da ƙwayoyin cuta ba, kamar su. murjani kaguwa, amma kuma microscopic da parasitic siffofin tare da rage yawan kwayoyin halitta.
Ciyarwar masu cin abinci
Ɗaya daga cikin manyan halayen waɗannan dabbobin shine yawancin su dabbobiDon samun damar yin amfani da su tentacles da kuma cndocyteswanda ke sakin abin da ke damun jiki da guba ko kuma ya hana abin ganima. Daga baya, ta hanyar haɗin gwiwar motsi na tentcles da baki, ana ɗaukar abincin a cikin rami na ciki.
Cnidarians suna cin abinci da farko kananan planktonic crustaceans, tsutsa de pecestsutsotsi da sauran invertebrates. Pelagic jellyfish na iya kamawa kananan kifiYayin da anemones da murjani ke farautar ganima da ke wucewa kusa da tantunansu. Wasu nau'ikan sune masu zubar da ciki kuma suna amfani da ragowar kwayoyin halitta waɗanda suka kai ga tantunansu.
Akwai kuma cnidarians da suke amfani da su narkar da kwayoyin halitta a cikin ruwa, ɗaukar abubuwan gina jiki kai tsaye ta cikin epidermis ko gastrodermis. Kuma, a cikin murjani da yawa da wasu anemones, an kafa dangantakar symbiotic tare da microscopic photosynthetic algae (zooxanthellae) da ke zaune a cikin sel. Wadannan algae suna yin photosynthesis kuma suna ba wa cnidarrian wani muhimmin sashi na sa kwayoyin carbon, yayin da cnidarian ke ba su kariya da samun haske.
La narkewa Yana farawa a cikin a extracellular a cikin kogon gastrovascular ta hanyar enzymes da aka ɓoye ta ƙwayoyin glandular na gastrodermis. Abubuwan da aka narkar da su na ɗan lokaci suna phagocytosed ta ƙwayoyin tsoka masu gina jiki da cikakken narkewa a cikin intracellularTa wannan hanyar, ana rarraba abubuwan gina jiki ta hanyar yaduwa zuwa ga dukkan kwayoyin halitta.
Haihuwa da tsarin rayuwa na cnidarians
Game da haifuwar su, cnidarians na iya haifuwa duka biyu a cikin a mai haila kamar yadda jima'ikuma a cikin kungiyoyi da yawa a canji na tsararraki tsakanin lokaci na polyp na asexual da lokacin medusa na jima'i.
Samun haihuwa
La asexual haifuwa shi ne hali na lokaci na polyp kuma yana ba da damar haɓaka da sauri a cikin adadin mutane a cikin mulkin mallaka. Ana samun wannan ta hanyoyi da yawa:
- Shekaru: samuwar kananan harbe-harbe na gefe wanda ke girma kuma ya rabu da iyayen mutum, yana haifar da sababbin polyps ko matasa jellyfish.
- TsagewaA wasu anthozoans, gutsuttsura na mutum (misali, wani ɓangare na faifan feda) na iya cirewa da sake haifar da sabon, cikakken polyp.
- KarfafawaA cikin scyphozoans, scyphistome (polyp) sassan suna juyawa, suna samar da fayafai da ake kira. ephyras, wanda ke ware ɗaya bayan ɗaya kuma ya canza zuwa jellyfish matasa.
Godiya ga waɗannan dabarun, yawancin murjani da anemones mazauna suna iya sake haifuwa bayan lalacewa ta jiki, kuma wasu nau'in na iya rayuwa na tsawon lokaci mai tsawo a matakin mallaka.
Haihuwar jima'i da tsutsa
La haifuwar jima'i Yawancin lokaci ana danganta shi da lokaci na medusa a cikin hydrozoans, scyphozoans, da cubozoans, kodayake a cikin anthozoans yana faruwa a cikin matakin polyp. Yawancin nau'ikan sune dasawa (wasu maza da mata daban-daban), ko da yake akwai kuma jinsuna hermaphrodites.
A yawancin lokuta, maza da mata duka suna sakin nasu gametes (kwai da maniyyi) a cikin ruwa a cikin wani tsari na hayayyafaHaɗuwa yawanci na waje, yana haifar da kwai da ke tasowa planula tsutsaciliated da iyo. Wannan tsutsa tana iyo da yardar rai na wani lokaci mai canzawa, takan zauna a kan abin da ya dace, kuma ta rikide zuwa wani matashin polyp, fara sabon mallaka ko kadaici.
A wasu cnidarians, hadi zai iya zama yanar gizoTaurari suna tasowa a cikin ƙwanƙwasa na musamman na medusa ko polyp kafin a sake su. Hakanan akwai bambance-bambancen inda tsutsa ke canzawa da sauri zuwa medusa, ragewa ko kawar da matakin polyp.
Ana kiran wannan cikakken zagayowar tare da bayyanannen canji tsakanin asexual polyp da medusa jima'i metagenetic sake zagayowarLokacin da ɗaya daga cikin matakan ya ragu sosai ko ba ya nan, ana kiransa da zagayowar. hypogenetic, kamar yadda yake faruwa a cikin ruwa mai tsabta (polyp kawai) ko a wasu jellyfish waɗanda ke da ƙarancin lokaci na polypoid.
La rai rai Tsawon rayuwar cnidarians yana da matukar canji: wasu ƙananan polyps suna rayuwa ƙasa da 10 kwanakinyayin da za a iya kiyaye wasu murjani na reef na dubban shekaru ta hanyar ci gaba da ci gaban mulkin mallaka da bunƙasa.
Duk waɗannan halayen suna sa cnidarians su zama rukuni mai ban sha'awa daga duka mahangar kimiyya da muhalli. juyin halitta a matsayin nau'in muhalli, tare da tsari mai sauƙi amma matuƙar tasiri, masu ikon mallakar komai daga wuraren tafki na tsaka-tsaki zuwa zurfin abyssal da samar da wasu mafi kyawun halittun ruwa a duniya.
Ina fata da wannan bayanin zaku iya ƙara koyo game da cnidarians da manyan azuzuwan da nau'ikan da ke wanzuwa, da kuma fahimtar yanayin halittarsu, dabarun ciyar da su da kuma sarƙaƙƙiya na zagayowar haihuwarsu.
