Indlela yokuzala kunye nokuphuhliswa kweembumba
Ookrebe banokuzala ngeendlela ezimbini ezahlukeneyo: viviparity y ukungabikho kwe-oviparity. I-Viviparity kuxa i-embryo ikhula ngaphakathi kwesibeleko sikamama kwaye izalwa iphila, ngelixa i-oviparity kuxa ookrebe babeka amaqanda athi kamva aqanduselwe. Zombini ezi ndlela zineengenelo kunye nezingeloncedo malunga nokhuseleko lokuqandusela kunye nesondlo.
I-Viviparity ibonisa ukhuseleko olukhulu kwiimbumba njengoko zikhula ngaphakathi komama. Ukutya kwe-embryo kunokwenzeka ngeendlela ezintathu: lecithotrophy (i-embryo itya kwi-yolk sac), histotrophy (umama ubonelela ngezondlo) kunye oophagia (i-embryo itya ezinye iimbumba). I-Oviparity, kwelinye icala, ayikhuselekanga kangako njengoko iqanda libekwe phantsi kolwandle kwaye liyakwazi ukuphangwa zezinye izilwanyana ngaphambi kokuba ziqanduselwe.
Oviparous sharks kunye nenkqubo yabo yokuzalwa
Ookrebe be-oviparous babeka amaqanda agcinwe kwi-capsules yesikhumba eyaziwa ngokuba yi "mermaid's purses". Ezi capsules zinemicu ekupheleni ezinceda ukuba zibambelele kwizinto ezingaphantsi kwamanzi, ezifana namatye kunye ne-algae, ukuthintela ukuba zingakhukuliswa yimisinga.
- Emva kokuba i-capsule ifakwe kakuhle, i-embryo iqala ukukhula ngaphakathi kwaye ityisa i-yolk sac ekhoyo kwi-capsule. Le nkqubo inokuthatha iinyanga eziliqela, kuxhomekeka kudidi lukakrebe.
Nje ukuba ushaka umntwana, ogama lingu "pup", ukhule ngokupheleleyo kwaye ulungele ukuthatha ihlabathi, ephula i-capsule ngamazinyo akhe kwaye athambekele emanzini olwandle.
I-Viviparous sharks kunye nenkqubo yabo yokuzalwa
Njengoko besesitshilo ngaphambilana, ookrebe ekuthiwa zii<em>viviparous sharks bazala bebancinane emva kokuba bekhulele esibelekweni sikanina.
- Kwezi meko, i-embryo ityiswa yi-placenta efana naleyo yezilwanyana ezanyisayo ezinika i-embryo ioksijini kunye nezondlo.
Xa amantshontsho ekhule ngokupheleleyo, umama wokrebe uyazala. Le nkqubo yaziwa ngokuba iparto kwaye inokwahluka ixesha ngalinye, ngokuxhomekeke kuhlobo lokrebe kunye neemeko zokusingqongileyo ngelo xesha.
Ukuziphatha komama kunye nokusinda kwenjana
Ookrebe ngokuqhelekileyo ababonisi ukuziphatha okusebenzayo kwabazali emva kokuzalwa. Emva kokuba bezale okanye bezalela amaqanda abo, ookrebe ngokuqhelekileyo abanikezeli ngokhuseleko olungakumbi okanye banyamekele amantshontsho abo. Oku kuthetha ukuba amantshontsho kakrebe kufuneka azikhusele ukususela ekuzalweni kwawo. Ookrebe abancinci sele bezelwe benethuku labo lokuzingela kunye nokusinda.
Izinga lokusinda kwentshontsho liyahluka phakathi kweentlobo ezahlukeneyo zookrebe. Ngokomzekelo, ezinye iintlobo ze-viviparous sharks zinokuba nezinga eliphezulu lokusinda kune-oviparous, kuba zizalwa zikhule ngokupheleleyo kwaye zikhulu ngobukhulu, zivumela ukuba ziphephe izilwanyana ezidliwayo ngokufanelekileyo.
Ukubaluleka kokuzalwa kunye nokugcinwa kookrebe
Ukuzalwa kookrebe sisiganeko esimangalisayo nesibalulekileyo sokugcina ulungelelwano lwendalo yeelwandle zethu. Ezi zilwanyana zidlala indima ebaluleke kakhulu kwikhonkco lokutya, zinceda ukugcina amaxhoba alawulwayo kunye nokukhuthaza ukuhlukahluka kweentlobo zaselwandle.
Nangona kunjalo, ukwanda koxinzelelo lokuloba kunye nokuwohloka kwendawo yokuhlala kubeka esichengeni iintlobo ezininzi zookrebe. Ukuqinisekisa ukusinda kwezi zilwanyana zibangel’ umdla, kubalulekile ukuxhasa amaphulo olondolozo lwendalo, ukufundisa uluntu ngezi zilwanyana zibalulekileyo zaselwandle, nokukhuthaza ukulondolozwa kwendalo yazo yendalo.