Phakathi kwezidalwa eziphilayo zasendulo ezitholakala phansi kolwandle kukhona ama- cnidarians . Le phylum yakhiwe yizinto eziphilayo zasemanzini , futhi igama layo livela ohlotsheni lweseli oluhlukile olubizwa ngokuthi ama-cnidocytes , okuyizinto ezenza lezi zinhlobo zibe ezikhethekile. Njengamanje, cishe izinhlobo ezingu-11.000 zama-cnidarians zaziwa , zihlukaniswe ngezigaba ezahlukene, izinhlobo, kanye nezinhlobo, ezisakazeke cishe kuwo wonke amalwandle omhlaba kanye nakwezinye izindawo zamanzi ahlanzekile.
Kulesi sihloko sizokutshela ngokuningiliziwe ngezici , indawo yokuhlala , amakilasi , ukudla , umjikelezo wokuphila kanye nokuzala kwama-cnidarians, futhi sihlanganisa ulwazi oluthuthukisiwe lokwakheka komzimba kanye nolwezinto eziphilayo ukuze siqonde ukuthi lezi zilwane zinjani nokuthi ziphila kanjani.
Izici eziyinhloko zama-cnidarians
Phakathi kwazo zonke izinhlobo ezakha leli qembu lezilwane, sithola amakhorali , i-jellyfish , ama-anemones olwandle , ama-hydra , kanye namakoloni ahlukahlukene amakoloni . Ngaphakathi kwama-cnidarians, sithola izinhlobo eziyinhloko ze-jellyfish ezitholakala emhlabeni wonke. Lezi yizinhlobo zasolwandle ikakhulukazi, yize ezinye zikwazile ukuhlala ezindaweni zamanzi ahlanzekile, njenge-hydra ethile kanye ne-jellyfish ezivela emachibini amakhulu.
Ngokuvamile zincane futhi zithambile , okusho ukuthi zinokunyakaza okulinganiselwe futhi zihlala zinamathele ku-substrate (efana nama-anemones nama-corals). Ezinye izinhlobo zincane futhi zibhekwa njenge-planktonic , zintanta futhi zibhukuda ekholomu yamanzi. Ubukhulu balezi zilwane busukela ezinhlotsheni ezincane kakhulu ezingamamilimitha ambalwa kuya kuma-jellyfish amakhulu angaphezu kwamamitha angama-20 ubude, okuhlanganisa nezimpondo zawo.
Ziyizinto eziphilayo ze-diploblastic , okusho ukuthi zikhula kusukela ezingqimbeni ezimbili zombungu: i- ectoderm (eveza i-epidermis) kanye ne- endoderm (eveza i-gastrodermis). Phakathi kwalezi zingqimba kukhona ungqimba lwe-gelatinous olubizwa ngokuthi i-mesoglea , olukhula kakhulu ku-jellyfish futhi luncane kuma-polyps amaningi. Ngenxa yale nhlangano, ama-cnidarians abonisa inhlangano yezinga lezicubu : anezicubu kodwa awanazo izitho eziyinkimbinkimbi njengenhliziyo, amaphaphu, izinso, noma ubuchopho obuphakathi.
Iningi lama-cnidarian linokulingana kwe-radial , okusho ukuthi imizimba yawo ihlelwe eduze kwe-axis ephakathi yomlomo ne-aboral. Kwamanye amaqembu, lokhu kulingana kungashintshwa kube ukulingana kwe-biradial noma kwe-tetraradial , njengoba kwenzeka kuma-jellyfish amaningi, lapho umzimba ungahlukaniswa khona ube yizikwele ezine ezilinganayo noma ube yimikhakha ephindaphindwayo eyisithupha noma eyisishiyagalombili.
Isici esivelele kakhulu sama-cnidarians yiseli elihlabayo lapho athola khona igama lawo: i- cnidocyte . Lawa maseli atholakala kuphela kwi-phylum Cnidaria futhi akha isici sayo sokuxilonga.
Ama-Cnidocytes: "isikhali esiyimfihlo" sama-cnidarians
Ama-Cnidocyte angamaseli akwazi ukudubula intambo ehlabayo . Ngaphakathi, aqukethe i-capsule ebizwa ngokuthi i -cnid noma i-nematocyst , lapho kugcinwa khona intambo egoqekile. Lapho i-cnidocyte ithola isikhuthazo semishini noma samakhemikhali (isibonelo, ukuthintwa yisilwane), i-operculum encane iyavuleka bese intambo idubula ngesivinini esikhulu, ibhoboze noma ibambe isisulu futhi ikhiphe izinto ezinobuthi, ezinamathelayo, noma ezibambayo.
Lawa ma-cnidocyte agxile kakhulu ezintendeni nasezindaweni ezizungezile umlomo, kodwa angatholakala futhi esakazeke kulo lonke i-epidermis kanye ne-gastrodermis. Ukuphuma kwawo kushesha kakhulu, ngokulandelana kwama-millisecond, futhi kwezinye izinhlobo ubuthi bunamandla kangangokuthi bungathinta kakhulu izilwane ezinkulu ezinomgogodla, okuhlanganisa nabantu.
Ama-Cnidarians awanazo izinhlelo ezikhethekile zokukhipha ukungcola, zokuphefumula, kanye nezokujikeleza kwegazi . Yonke le misebenzi yenziwa ngomgodi wesisu kanye nobuso bomzimba. Ukushintshana kwegesi (i-oxygen kanye ne-carbon dioxide) kwenzeka ngokusabalala okuqondile ngezingqimba zamaseli agezwa ngamanzi.
Inhlangano yomzimba kanye ne-gastrovascular cavity
Umzimba wama-cnidarians umise okwesikhwama . Ane-cavity eyodwa yangaphakathi ebizwa ngokuthi i-gastrovascular cavity noma i-coelenterate , exhumana nengaphandle ngomnyango owodwa osebenza njengomlomo kanye ne-anus . Lo mgodi wenza imisebenzi eminingana ngesikhathi esisodwa:
- Ukugaya ukudla ngama-enzyme akhiqizwe yi-gastrodermis.
- Ukusatshalaliswa komsoco nomoya-mpilo emangqamuzaneni omzimba.
- Ukulahlwa ngaphandle ngokuvula umlomo ofanayo.
- Ezimweni zenza njenge i-hydrostatic skeleton, lapho igcwele amanzi futhi isetshenziswa njengesisekelo.
Ama -tentacles ahlelwe azungeze umlomo futhi inani lawo livame ukuba ngama -multiples angu-6 noma angu-8 , kuye ngokuthi iqembu likuphi (ikakhulukazi libonakala kuma-anthozoan). La ma-tentacles ayaguquguquka, ayathutha, futhi acebile ngama-cnidocytes, okuwavumela ukuthi abambe izisulu, azivikele, futhi kwezinye izimo, ahambe ngendlela elinganiselwe.
Njengoba ziyizinto eziphilayo zasendulo kakhulu, ama-cnidarians awanayo i-cephalization ; okungukuthi, awanayo ikhanda elihlukile noma uhlelo lwezinzwa oluphakathi. Uhlelo lwawo lwezinzwa luyinethiwekhi elula yama-neurons (i-nerve plexus) asatshalaliswa kulo lonke i-ectoderm kanye, ngezinga elincane, i-gastrodermis. Noma kunjalo, amaqembu amaningi athuthukisa amangqamuzana ezinzwa kanye nezitho ezilula njenge-statocysts (ukulinganisela) kanye ne-ocelli (yokubona ukukhanya nesithunzi).
Amafomu omzimba: i-polyp ne-jellyfish
Amaphethini omzimba ayinhloko atholakala kule phylum yifomu le- polyp kanye nefomu le -medusa . Zombili zinesakhiwo esifanayo esiyisisekelo (umgodi wesisu, ama-tentacles, nomlomo) kodwa ziqondiswe ngokuphambene futhi zivumelaniswe nendlela yokuphila ehlukene.
- I-Polyp: yindlela sesileIfakwe ku-substrate. Inefomu i-cylindricalnge-aboral end enamathiselwe (nge-pedal disc noma isisekelo) emadwaleni, amagobolondo, noma i-sediment, kanye nokuphela komlomo okubheke phezulu ngomlomo ozungezwe amatende. Kungaba njalo Uwedwa (ama-anemones) noma ifomu amakoloni (amakhorali amaningi nama-hydrozoans).
- Medusa: yindlela mobile noma i-pelagic. Inomumo we insimbi noma isambulela (isambulela), indawo engaphansi ibheke phezulu kanye nomlomo ubheke phansi phakathi nesambulela, evamise ukunwebeka kube i isibamboAmathente alenga onqenqemeni lwesambulela. Ukuhamba kwazo kusekelwe ekufinyezweni okunesigqi kwesambulela esihambisa amanzi.
Ezinhlotsheni eziningi kune -polymorphism ebalulekile : ngaphakathi kwekoloni elifanayo kungase kube nezinhlobo ezingochwepheshe bokudla, ukuzivikela noma ukuzala (ukudla, ukuzivikela kanye nokuzala ama-zooid).
Ukuhlukaniswa kwama-cnidarians
Izinhlobo eziningi ze-cnidarian zikhiqiza amakoloni akhiwe yizinto eziphilayo ezibizwa ngokuthi ama-zooids , okungaba ama-polyps, ama-medusae, noma izinhlobo eziphakathi. Phakathi kwezinhlobo eziyinhloko ezisetshenziselwa ukuhlukanisa ama-cnidarian kukhona ezinye ezizalana ngokungahambisani nobulili ngama-polyps kanti ezinye ngokocansi ngama-medusae , futhi ezimweni eziningi, zombili izindlela ziyashintshana ngaphakathi komjikelezo wokuphila ofanayo.
Ezinye izinhlobo zingaguquka zisuka esigabeni se-polyp ziye esigabeni se-medusa izikhathi eziningana ngesikhathi somjikelezo wazo wokuphila, kanti ezinye zibonisa isigaba se-polyp noma se-medusa kuphela. Ngokwe-taxonomically, i-phylum Cnidaria ihlukaniswe ngamaqembu amancane amaningana, kodwa ngezinhloso ezingokoqobo, kusetshenziswa amakilasi amane amakhulu endabuko: i-Anthozoa, i-Cubozoa, i-Hydrozoa, ne-Scyphozoa . Ngaphezu kwalokho, kunezinye izinhlobo ezifana ne -Staurozoa kanye ne- cnidarians ezidla izimila (i-Myxozoa ne-Polypodiozoa), ezikhulisa kakhulu ukuhlukahluka kwazo.
Anthozoa
Leli klasi lihlanganisa zonke izilwane ezaziwa ngokuthi ama-anemones , ama-coral, kanye nama-sea pens . Ku-Anthozoa, kuvela isigaba se-polyp kuphela ; akukho sakhiwo se-medusa esizimele. Lawa ma-polyp angaba ngawodwana (ama-anemones amakhulu) noma akhe amakoloni amakhulu (ama-coral akha amatshe).
I-polyp ingazala kokubili ngokungaxubeki ngokobulili ( ukuhluma, ukuqhekeka) kanye nangokobulili , ikhiqize ama-polyp amasha. Lezi zilwane zinobudoda ngokuphelele futhi kumele zihlale zinamathele unomphela ku-substrate ngokusebenzisa i-pedal disc yazo noma isakhiwo esifanayo. Ama -tentacles akhona kulezi zilwane atholakala ngokuphindaphinda okungu-6 (Hexacorallia) noma okungu-8 (Octocorallia), okusetshenziswa njengendlela yokuhlukanisa yangaphakathi.
Umgodi wazo wesisu uhlukaniswe yi-septa noma i-mesenteries ekhulisa indawo engaphezulu yokugaya nokumunca. Lawa ma-septa avela ku-gastrodermis futhi aqhubekele ku-mesoglea, akha izingxenye zangaphakathi. Ama-anthozoan amaningi, ikakhulukazi ama-coral anamatshe, akhipha amathambo angaphandle e-calcium carbonate , aqongelela izizukulwane ngezizukulwane, adala ama -coral reef adumile futhi ayisihloko esifundwayo ezindaweni zasolwandle.
eCubozoa
I-Cubozoa ihlanganisa i-box jellyfish kanye ne-sea wasps . Lezi zinhlobo zinesigaba se-medusa esithuthukisiwe kahle , kanti isigaba se-polyp sincane futhi sihlala isikhathi esifushane . I-medusa inesimo se -cubic esihlukile , lapho igama layo livela khona: insimbi inezinhlangothi ezine ezinemiphetho echazwe kahle.
Unqenqema lwalezi zinhlanzi lugoqeka ngaphakathi ukuze lwakhe isakhiwo esifana nesembozo esibizwa ngokuthi i- velarium , esithuthukisa ukusebenza kahle kokubhukuda. I-tentacles eyodwa noma ngaphezulu enamandla inamathele emakhoneni ensimbi , ifakwe esisekelweni esikhulu esibizwa ngokuthi i-pedalium . Futhi inezitho eziyinkimbinkimbi zokuzwa (i-rhopallia) ezine-ocelli ethuthukisiwe kahle ezivumela ukuthi ziqonde ekholomu yamanzi.
Lezi zilwane ziyaziwa ngokuluma kwazo okunobuthi kakhulu , okungaba yingozi kubantu ezinhlotsheni ezithile, okubangela ubuhlungu obukhulu, izinkinga zenhliziyo nemithambo yokuphefumula. Ngenxa yalesi sizathu, i-box jellyfish ibhekwa njengezinye zezilwane ezinobuthi kakhulu emhlabeni wasolwandle.
I-Hydrozoa
Leli qembu lezilwane laziwa kakhulu ngokuthi i-hydromedusae futhi lihlanganisa nama-hydropolyps amaningi . Eziningi zalezi zinhlobo, kukhona ukushintshana kwezizukulwane phakathi kwesigaba se-polyp esingenaso ucansi kanye nesigaba se-medusa socansi.
Isigaba se-polyp sivame ukuhleleka ngamakholoni abantu abahlukahlukene . Lokhu kusho ukuthi ngaphakathi kwekholoni efanayo kunezinhlobo ezinezinhlobo nemisebenzi ehlukene : ezinye zigxile ekondleni, ezinye ekuzivikeleni, kanti ezinye zikhiqiza. Lokhu kuhlukahluka kuvumela amakholoni ukuthi asebenze cishe njenge-superorganism esebenza kahle kakhulu.
I-jellyfish yalesi sigaba ine- velum (yingakho igama layo liyi-craspedota jellyfish) efana ne-velarium ye-box jellyfish, yize inemvelaphi nesakhiwo esihlukile. Ayinawo ama-cnidocytes emgodini we-gastrovascular, futhi ama-gonad awo avela e-ectodermal . Ngokungafani nama-scyphozoan nama-anthozoan, ayinawo umgodi we-gastrovascular ohlukaniswe yi-internal septa.
I-Scyphozoa
Kuleli qembu lezilwane , isigaba se-medusa sibonakala siphezulu , futhi sibhekwa njenge- "jellyfish yangempela ." Isigaba sabo se-polyp (i-scyphopolyp noma i-scyphistoma) sincane kakhulu futhi sivame ukunganakwa. Ama-Scyphomedusae ngokuvamile makhulu kune-hydromedusae, futhi kwezinye izinhlobo insimbi ingafinyelela ngaphezu kwemitha ububanzi.
Uma zifika esigabeni se-medusa , azinawo ama-velum , yingakho zibizwa ngokuthi i -acraspedote medusae , kodwa zine -sensory rhopalia kanye nama-cnidocytes emgodini we-gastrovascular. Ngokungafani ne-class Hydrozoa, leli klasi lama-cnidarians linomgodi we-gastrovascular ohlukaniswe kancane ngama-septa amane angaphelele endaweni ephakathi, okuhlukanisa umgodi ube yizikhwama ezine zesisu . Lokhu kuhleleka kwangaphakathi kuqinisa ukulingana kwazo kwe-tetraradial.
Amanye amaqembu ama-cnidarians
Nakuba amakilasi amane ashiwo ngenhla aziwa kakhulu, ukuhlukaniswa kwamanje kwama-cnidarians kuhlanganisa:
- I-Staurozoa: i-ssile, i-jellyfish emise okwenkomishi enamathiselwe ku-substrate ngohlanga. Zimelela amafomu aphakathi phakathi kwama-polyps kanye ne-medusae.
- I-Myxozoa: ama-cnidarians ama-parasites amancane de peces nezinye izilwane ezinomgogodla zasemanzini, osekuyisikhathi eside zibhekwa njenge-protozoa.
- I-Polypodiozoa: ama-cnidarian angama-parasitic ahlala ngaphakathi kwamaseli ezinye izilwane, anemijikelezo yokuphila ekhetheke kakhulu.
La maqembu abonisa ukuthi i-phylum Cnidaria ayihlanganisi nje kuphela i-jellyfish emangalisayo nama-corals ahlaba umxhwele kanye nezinto eziphilayo ezihlobene nayo, njengezinkalankala zamakhorali , kodwa futhi nezinhlobo ezincane neziyizinambuzane ezinezakhi zofuzo ezincishisiwe kakhulu.
Ukondla ama-cnidarians
Esinye sezici eziyinhloko zalezi zilwane ukuthi iningi lazo lidla inyama . Ukuze zibambe inyamazane yazo, zisebenzisa ama-tentacles nama -cnidocytes azo , akhipha into ehlabayo ebulala noma evimbela inyamazane. Ngemva kwalokho, ngokunyakaza okuhlelekile kwama-tentacles nomlomo, ukudla kuthathwa kungene emgodini wesisu.
Ama-Cnidarians adla ngokuyinhloko ama-crustaceans amancane e-planktonicizibungu de pecesizikelemu nezinye izilwane ezingenamgogodla. I-Pelagic jellyfish ingabamba ngisho izinhlanzi ezincaneNgenkathi ama-anemones namakhorali ezingela inyamazane edlula eduze kwamatende awo. Ezinye izinhlobo zikhona ama-scavenger futhi basebenzisa ngokunenzuzo izinsalela eziphilayo ezifinyelela emathendeni abo.
Kukhona nama-cnidarians asebenzisa izinto eziphilayo ezincibilikisiwe emanzini, amunca izakhamzimba ngqo nge-epidermis noma i-gastrodermis yawo. Futhi, kuma-coral amaningi nakwamanye ama-anemones, kwakheka ubudlelwano bokubambisana ne- algae ye-photosynthetic (i-zooxanthellae) ehlala ngaphakathi kwamaseli awo. Lawa ma-algae enza i-photosynthesis futhi anikeza i-cnidarian ingxenye enkulu ye -carbon yayo ephilayo , kuyilapho i-cnidarian iyinikeza isivikelo nokufinyelela ekukhanyeni.
Ukugaya kuqala ngaphandle kwesikhumba emgodini wesisu ngama-enzyme akhishwa amaseli ezindlala ze-gastrodermis. Izingcezu ezigaywe kancane zibe sezikhishwa ngamaseli emisipha anomsoco bese ziqeda ukugaya ngaphakathi kweseli . Ngale ndlela, izakhamzimba zisatshalaliswa ngokusabalala kuwo wonke amaseli omzimba.
Ukukhiqizwa kanye nomjikelezo wempilo wama-cnidarians
Ngokuphathelene nokuzala kwabo, ama-cnidarians angazala kokubili ngaphandle kocansi kanye nangokobulili , futhi emaqenjini amaningi kukhona ukushintshana kwezizukulwane phakathi kwesigaba se-polyp esingenaso ucansi kanye nesigaba se-medusa yocansi.
Ukukhiqizwa kabusha ngokobulili
Ukuzala okungenabo ubulili kuyinto evamile esigabeni se -polyp futhi kuvumela ukwanda okusheshayo kwenani labantu ekoloni. Kwenzeka ngezindlela eziningana:
- Ukuqothula: ukwakheka kwamahlumela amancane asemaceleni akhula futhi ahlukane nomzali ngamunye, okubangela ama-polyps amasha noma i-jellyfish encane.
- UqhekekoKwamanye ama-anthozoans, izingcezwana zomuntu ngamunye (isibonelo, ingxenye ye-pedal disc) zingakhipha futhi zikhiqize kabusha i-polyp entsha, ephelele.
- UkuqiniswaKuma-scyphozoans, amasegimenti e-scyphistome (polyp) ngokuphambana, akha ama-disc aqoqiwe abizwa ngokuthi ama-ephyras, ezihlukanisa ngayinye ngayinye bese zishintsha zibe i-jellyfish encane.
Ngenxa yalezi zindlela, amakoloni amaningi amakhorali nama-anemones angakhula kabusha ngemva kokulimala ngokomzimba, kanti ezinye izinhlobo zingaphila isikhathi eside kakhulu ezingeni lamakholoni.
Ukuzalana ngokocansi kanye nezibungu
Ukuzala ngokocansi kuvame ukuhlotshaniswa nesigaba se -medusa kuma-hydrozoan, ama-scyphozoan, nama-cubozoan, yize kuma-anthozoan kwenzeka esigabeni se-polyp. Izinhlobo eziningi zi- dioecious (abesilisa nabesifazane abahlukene), yize nezinhlobo ze -hermaphroditic zikhona.
Ezimweni eziningi, abesilisa nabesifazane bakhipha ama-gametes abo (amaqanda kanye nesidoda) emanzini ngesikhathi sokuzala . Ukukhulelwa kuvame ukuba ngaphandle , okuholela eqandeni elikhula libe yi- ciliated, swimming planula larva . Lesi sibungu sibhukuda ngokukhululeka isikhathi esiguquguqukayo, sihlale endaweni efanele, bese siguquka sibe yi- polyp encane , siqale ikoloni elisha noma sibe umuntu oyedwa.
Kwamanye ama-cnidarians, ukukhulelwa kungaba ngaphakathi , lapho ama-embryo ekhula emihumeni ekhethekile ye-medusa noma i-polyp ngaphambi kokuba akhishwe. Kukhona nezinguquko lapho i-larva ishintsha ngokushesha ibe yi-medusa, inciphisa noma iqede isigaba se-polyp.
Lo mjikelezo ophelele onokushintshana okucacile phakathi kwe-polyp engaxubile kanye ne-medusa yocansi ubizwa ngokuthi umjikelezo we-metagenetic . Uma esinye sezigaba sincishisiwe kakhulu noma singekho, sibizwa ngokuthi umjikelezo we-hypogenetic , njengoba kwenzeka kuma-hydra ahlanzekile (ama-polyp kuphela) noma kwamanye ama-medusa angenaso isigaba se-polyp.
Isikhathi sokuphila sama-cnidarians siyahlukahluka kakhulu: amanye ama-polyp amancane aphila isikhathi esingaphansi kwezinsuku eziyi-10 , kanti amanye ama-coral asezindaweni zasolwandle angaphila izinkulungwane zeminyaka ngokukhula okuqhubekayo kanye nokuhluma kwekoloni.
Zonke lezi zici zenza ama-cnidarians abe yiqembu elithakazelisayo kokubili ngokombono wokuziphendukela kwemvelo kanye nowemvelo, anezakhiwo ezilula kodwa eziphumelelayo kakhulu, ezikwazi ukuqoqa yonke into kusukela emachibini aphakathi kwamaza kuya ekujuleni kwasekujuleni futhi zakhe ezinye zezindawo zemvelo zasolwandle ezicebe kakhulu emhlabeni.
Ngiyethemba ukuthi ngalolu lwazi ungafunda kabanzi ngama-cnidarians kanye nezinhlobo eziyinhloko ezikhona, kanye nokuqonda kangcono ukwakheka kwawo, amasu azo okuphakela kanye nobunzima bemijikelezo yawo yokuzala.
