Oshaka abanamakhanda amabili baqala ukuhlangana olwandle. Ososayensi abakakwazi ukuthola izizathu zalesi simo.
Ushaka onamakhanda amabili angabonakala njengomlingiswa kumovie yezindaba eziqanjiwe zesayensi, kepha manje sekuyiqiniso okubhekwana nalo kaningi. Inani elikhulu lososayensi likholelwa ukuthi imbangela yokuguquka kwezakhi zofuzo ukungajwayelekile kwezakhi zofuzo okubangelwa ukuncipha kwenqwaba yezinhlanzi futhi mhlawumbe nokungcola kwemvelo.
Ngokuvamile, kunezinto ezimbalwa ezingabizwa phakathi kwezimbangela zokuphambuka okunjalo, kufaka phakathi ukutheleleka ngegciwane kanye nokwehla okwesabekayo echibini lezakhi zofuzo, okugcina kuholele ekuzalaneni nasekukhuleni kokungajwayelekile kofuzo.
Konke kwaqala eminyakeni embalwa eyedlule, lapho abadobi babedonsa ushaka wenkunzi emanzini ogwini lwaseFlorida, esibelethweni sakhe kwakukhona umbungu onamakhanda amabili. Futhi ngo-2008, esevele eselwandle i-Indian, omunye umdobi wathola umbungu kashaka onamakhanda amabili aluhlaza okwesibhakabhaka. Ngo-2011, abacwaningi abasebenza ngale nto yamawele aseSiamese bathola oshaka abalihlaza okwesibhakabhaka abanemibungu enamakhanda amabili emanzini asenyakatho-ntshonalanga yeMexico naseGulf of California. Yibo laba oshaka abakhiqiza isibalo esiphezulu semibungu enamakhanda aphindwe kabili, okuchazwa ngokwazi kwabo ukuzala inani elikhulu - lize lifike kuma-50 - inani lemidlwane ngasikhathi sinye.
Manje, abacwaningi baseSpain bathole umbungu onamakhanda amabili ka-cat shark ongajwayelekile (Galeus atlanticus). Ososayensi base-University of Malaga basebenze nemibungu ecishe ibe ngu-800 yalolu hlobo loshaka, befunda ngomsebenzi wohlelo lwabo lwezinhliziyo nemithambo yegazi. Kodwa-ke, ngenkathi benza lokho, bathola umbungu ongajwayelekile onamakhanda amabili.
Ikhanda ngalinye lalinomlomo, amehlo amabili, ukuvuleka kwama-gill amahlanu ohlangothini ngalunye, i-chord, nobuchopho. Kulokhu, womabili amakhanda adlulela emzimbeni owodwa, obejwayelekile ngokuphelele futhi unazo zonke izimpawu zesilwane esijwayelekile. Kodwa-ke, ukwakheka kwangaphakathi kwakungamangalisi kangako kunamakhanda amabili - emzimbeni kwakukhona isibindi ezimbili, imiphakathi emibili nezinhliziyo ezimbili, futhi kwakukhona nezisu ezimbili, yize zonke zazingumzimba owodwa.
Ngokwabaphenyi, umbungu uyiwele elihlangene elinamakhanda amabili, elenzeka ngezikhathi ezithile cishe kuwo wonke ama-vertebrate. Ososayensi ababhekene nalesi simo bakholelwa ukuthi uma umbungu otholakele unethuba lokuzalwa, ubungeke ukwazi ukuphila, ngoba ngalezi zimo zomzimba ubungeke ukwazi ukubhukuda ngokushesha nangempumelelo.
Ukuhluka kwalokhu kutholakala ukuthi lokhu kungokokuqala ukuthi umbungu onamakhanda amabili utholwe kushaka oviparous. Mhlawumbe yilesi simo esichaza iqiniso lokuthi amasampula anjalo awakaze awele ezandleni zabantu, ngokungafani nemibungu yoshaka abathandekayo. Ngasikhathi sinye, ngokusho kososayensi, akunakwenzeka ukuthi kuzokwenzeka ukuthi kuphenywe ngokuphelele le nto, ngoba ukutholwa okunjalo kuhlala kuyingozi futhi akunakwenzeka ukuqoqa inani elanele lezinto ezizocwaningwa.
