A pair of orcas working in concert have been killing great whites along a stretch of South African coastline since at least 2017, plundering the sharks’ nutrient-rich livers and discarding the rest. Scientists have been trying to make sense of the hunting approach, which has driven the sharks away from some parts of the coast around Cape Town, and now research has revealed a startling new twist in the behavior that could offer clues on what it might mean for the wider marine ecosystem. Scientists witnessed one of the hunters, a male orca known as Starboard, single-handedly kill a 2.5-meter juvenile white shark within a two-minute time frame last year. “Over two decades of annual visits to South Africa, I’ve observed the profound impact these killer whales have on the local white shark population. Seeing Starboard carry a white shark’s liver past our vessel is unforgettable,” said Dr. Primo Micarelli, a marine biologist at Italy’s Sharks Studies Center and the University of Siena who was aboard one of two vessels from which researchers observed the attack. “Despite my awe for these predators, I’m increasingly concerned about the coastal marine ecology balance,” Micarelli said. It’s not unprecedented for orcas, highly intelligent and social animals, to hunt large animals individually. However, it’s the first such occurrence involving what is one of the world’s largest predators — the great white shark — the researchers reported in a study published Friday in the African Journal of Marine Science. Starboard’s kill is at odds with more widely observed cooperative hunting behavior among orcas, which can surround large prey, such as sea lions, seals and sharks, and use their combined intelligence and strength to attack, said lead author Alison Towner, a doctoral researcher at Rhodes University. Previously observed attacks on great whites involved between two and six orcas and took up to two hours, according to the study. The event detailed in the study took place on June 18, 2023, 800 meters offshore close to Seal Island near Mossel Bay — about 400 kilometers east of Cape Town — where people on two vessels were observing the orcas. Less than an hour after arriving, a shark appeared near the surface, and researchers, tourists and others on board witnessed Starboard grip the left pectoral fin of a shark and “thrust forward with the shark several times before eventually eviscerating it” in less than two minutes, the study said. Later Starboard was photographed from one of the vessels with a “bloody piece of peach-colored liver in its mouth,” according to the study. (SD-Agencies) Words to Learn 相關(guān)詞匯 【一起】yīqǐ in concert together 【沒有先例的】méiyǒu xiānlì de unprecedented never having happened or existed in the past 早自2017 年起，一對虎鯨就開始在南非的一段海岸線上合作獵殺大白鯊，掠食鯊魚營養(yǎng)豐富的肝臟，然后將剩下的殘軀丟棄。 科學(xué)家們一直在試圖弄清它們的獵殺方式，因?yàn)榛ⅥL的存在已經(jīng)迫使鯊魚逃離開普敦周圍的部分海域。現(xiàn)在，研究揭示了這種捕獵行為一個(gè)令人震驚的新變化，可能為更廣泛的海洋生態(tài)系統(tǒng)變化提供了線索。 去年，科學(xué)家們親眼目睹了其中一頭名為“右舷”的雄性虎鯨在兩分鐘內(nèi)單槍匹馬地獵殺了一條 2.5米長的幼年白鯊。 意大利鯊魚研究中心和錫耶納大學(xué)的海洋生物學(xué)家普里莫?米卡雷利博士說： “二十多年來，我每年都去南非，觀察虎鯨對當(dāng)?shù)匕柞彅?shù)量的深遠(yuǎn)影響。看到“右舷”口銜著白鯊的肝臟從我們的船邊經(jīng)過，這景象令人難忘。”當(dāng)時(shí)兩只船上的人觀察到了這次捕獵行為。 米卡雷利說：“盡管我對這些掠食者充滿敬畏，但我越來越擔(dān)心沿海海洋生態(tài)平衡的問題。” 虎鯨是一種高智商的社會(huì)性動(dòng)物，單獨(dú)捕食大型動(dòng)物并非沒有先例。然而，研究人員報(bào)告說，這是大白鯊首次被單槍匹馬地獵殺，而大白鯊本身也是世界上最大的捕食者之一。這項(xiàng)研究在周五發(fā)表在《非洲海洋科學(xué)雜志》上。 研究第一作者、羅德斯大學(xué)博士研究員艾莉森?湯納說，“右舷”的殺戮行為與虎鯨更常見的合作狩獵行為不符。虎鯨可以圍獵大型動(dòng)物，如海獅、海豹和鯊魚，利用智慧和力量攻擊獵物。 論文記述，此前觀察到通常是兩到六頭虎鯨一起圍獵大白鯊，整個(gè)過程耗時(shí)兩小時(shí)之久。 研究詳述的案例發(fā)生在2023年6月18日，距離開普敦以東約400公里的莫塞爾灣附近的海豹島近海800米處，當(dāng)時(shí)兩艘船上的人正在觀察虎鯨。 研究說，船只抵達(dá)不到一小時(shí)，一條鯊魚出現(xiàn)在附近海面，研究人員、游客和船上的其他人目睹了“右舷”咬住鯊魚的左胸鰭，并“推著鯊魚向前行進(jìn)了幾次，最終將其撕碎”，時(shí)間不到兩分鐘。 研究報(bào)告稱，“右舷”后來被一艘船上的人拍到“嘴里含著一塊血淋淋的桃紅色肝臟”。 (Translated by Debra) | 