UMary Allen
Izinhlanzi yizilwane ezihlala emanzini kuphela. Baphefumula ngama-gill futhi ngokuvamile banesikhumba esinama-scaly. Zitholakala emhlabeni wonke, emifuleni, emachibini, nasolwandle. Izinhlanzi ziyizilwane ezinomgogodla ngoba zinomgogodla, njengezilwane ezincelisayo, izinyoni, izilwane ezihuquzelayo kanye nezilwane ezihlala emanzini.
Kunezinhlobo eziningi ezahlukene ezingabukeka zihluke kakhulu. Zihlukaniswa ngokuyinhloko ngokuthi uhlaka lwazo lwamathambo luqukethe uqwanga noma amathambo, abizwa nangokuthi amathambo. Oshaka nemisebe kungokwenhlanzi ene-cartilaginous, ezinye izinhlobo eziningi ziyizinhlanzi ezinamathambo. Ezinye izinhlobo zihlala emanzini anosawoti olwandle kuphela, ezinye kuphela emanzini ahlanzekile emifuleni nasemachibini. Noma kunjalo, abanye bayahamba baye emuva naphambili phakathi kolwandle nemifula phakathi nokuphila kwabo, njengama-eels nama-salmon.
Izinhlanzi eziningi zidla ulwelwe nezinye izitshalo zasemanzini. Ezinye izinhlanzi nazo zidla ezinye izinhlanzi kanye nezilwane zasemanzini ezincane, bese zibizwa ngokuthi izinhlanzi ezidla inyama. Izinhlanzi zibuye zibe ukudla kwezinye izilwane, njengezinyoni nezilwane ezincelisayo. Abantu bebelokhu bedoba izinhlanzi ukuze bazidle kusukela kudala. Namuhla, ukudoba kuyingxenye ebalulekile yezomnotho. Izinhlanzi ezidliwayo ezidume kakhulu zihlanganisa i-herring, i-mackerel, i-cod, ne-pollock. Nokho, ezinye izinhlobo zezilwane nazo zidotshwa ngokweqile, ngakho zisengozini yokushabalala futhi kufanele zivikelwe.
Inkulumo ethi “inhlanzi” ibalulekile ekuphileni kwethu kwansuku zonke. Ku-biology, nokho, alikho iqembu elifanayo elinaleli gama. Kukhona isigaba sezinhlanzi ze-cartilaginous, ezihlanganisa ushaka, isibonelo. Kodwa kukhona nezinhlanzi ezinamathambo njenge-eel, i-carp, nezinye eziningi. Abakhi ikilasi, kodwa uchungechunge. Alikho igama leqembu lezinhlanzi ze-cartilaginous nezinhlanzi ezinamathambo ndawonye. Bakha i-subphylum yezilwane ezinomgogodla. Ukuchaza lokhu ngokuningiliziwe kungaba nzima kakhulu.
Ziphila kanjani izinhlanzi?
Izinhlanzi azinayo izinga lokushisa elikhethekile. Umzimba wakhe uhlale ufudumele njengamanzi amzungezile. Ukuze uthole izinga lokushisa lomzimba elikhethekile, kuzothatha amandla amaningi kakhulu emanzini.
Izinhlanzi "zintanta" emanzini futhi ngokuvamile zihamba kancane. Ngakho-ke imisipha yabo ihlinzekwa kuphela ngenani elincane legazi, yingakho imhlophe. Phakathi kuphela kunemicu eqinile yokuhlinzeka ngegazi. Zibomvu. Izinhlanzi zidinga lezi zingxenye zemisipha ngomzamo omncane, isibonelo lapho zihlasela noma lapho zibaleka.
Izinhlanzi eziningi zizala ngamaqanda. Lezi zibizwa ngokuthi ama-roe uma nje zisesiswini sikamama. Ukuzalanisa owesilisa kwenzeka ngaphandle kwayo yomibili imizimba emanzini. Ukukhishwa kwamaqanda kubizwa ngokuthi "i-spawning", amaqanda abe ama-spawn. Ezinye izinhlanzi zimane zishiya amaqanda azo elele, kanti ezinye zinamathisele amaqanda azo emadwaleni noma ezitshalweni bese zibhukuda zihambe. Noma kunjalo, abanye bayinakekela kakhulu inzalo yabo.
Zimbalwa futhi izinhlanzi ezizala ukuphila zisencane. Ngaphezu koshaka nemisebe, lokhu kufaka nezinhlobo ezithile zezilwane esizijwayele kakhulu ezivela emanzini. Lezi zinhlanzi zidinga ubulili obubonakalayo ukuze amaqanda ahlanganiswe esibelethweni sikamama.
Yiziphi izitho ezikhethekile inhlanzi enazo?
Ukugaya inhlanzi kucishe kufane nezilwane ezincelisayo. Kukhona nezitho ezifanayo zalokhu. Kukhona nezinso ezimbili ezihlukanisa umchamo negazi. Ingxenye yomzimba ehlangene yokukhipha indle nomchamo ibizwa ngokuthi “i-cloaca”. Insikazi nayo izalela amaqanda ayo ngale ndlela yokuphuma. Kunezinhlobo ezimbalwa kuphela zokuphuma okukhethekile kwezilwane ezincane eziphilayo, isibonelo nge-carp ekhethekile.
Izinhlanzi ziphefumula ngamagill. Zimunca amanzi futhi zihlunge umoya-mpilo. Zibuyisela amanzi ne-carbon dioxide endaweni ezizungezile.
Ukujikeleza kwegazi ezinhlanzini kulula kunezilwane ezincelisayo.
Izinhlanzi zinenhliziyo negazi. Nokho, kokubili kulula ezilwaneni ezincelisayo nasezinyonini: inhliziyo iqala ngokumpompa igazi ngamagill. Ukusuka lapho igeleza iqonde emisipheni nakwezinye izitho futhi ibuyele enhliziyweni. Ngakho kunesifunda esisodwa kuphela, hhayi esiphindwe kabili njengezilwane ezincelisayo. Inhliziyo nayo ilula.
Izinhlanzi eziningi ziyakwazi ukubona nokunambitha njengezilwane ezincelisayo. Bavele banganuki ngoba abahlangani nomoya.
Yile ndlela isinye sokubhukuda esibukeka ngayo.
Isinye sokubhukuda sibaluleke kakhulu ezinhlanzini. Zitholakala kuphela ezinhlanzini ezinamathambo. Isinye sokubhukuda singagcwala noma sikhiphe okuningi. Lokhu kwenza inhlanzi ibonakale ilula noma isindayo emanzini. Bese “ingantanta” ngaphandle kwamandla. Ingaphinde ilele ivundlile emanzini futhi ivimbele ukuthi isuke ngephutha iye phambili noma emuva.
Izitho zomugqa osemaceleni nazo zikhethekile. Ziyizitho zemizwa ezikhethekile. Anwebeka phezu kwekhanda aze ayofika emsileni. Lokhu kuvumela izinhlanzi ukuzwa ukugeleza kwamanzi. Kodwa uyezwa futhi lapho enye inhlanzi isondela.