Scientists recently confirmed that the majority of the buffalo fish swimming around a remote desert lake in eastern Arizona, the United States are older than 100. The discovery builds on other recent research that has upended beliefs about the little-studied buffalo fish, a genus of five freshwater fish species native to North America. Just a few years ago, scientists thought that these fish, which come in an array of colors from chestnut brown to bluish, only lived into their mid-20s. However, a 2019 study revealed that bigmouth buffalo fish could live up to 112 years, making it the oldest known freshwater teleost, a group of about 12,000 ray-finned fish species found worldwide. Then in January, researchers announced the discovery of a 127-year-old bigmouth in Saskatchewan, Canada. The new study, published in Scientific Reports, confirmed that two more buffalo fish species — the smallmouth buffalo and the black buffalo — can live more than 100 years, making it the only known genus of animal besides the marine rockfish, Sebastes, that has three centenarian species. For the Arizona study, a few dozen anglers caught 222 buffalo fish at Apache Lake from July 2018 to July 2023. Twenty-three were humanely euthanized and donated to the research team, who estimated their ages by removing and analyzing tiny ear stones called otoliths. These calcium carbonate structures, which allow fish to hear and sense vibrations in the water, form a new layer each year that can be read somewhat like tree rings. Researchers identified individuals of all three species studied past 100 years old. What’s more, research has revealed that buffalo fish continue to live their best lives into their upper 80s and 90s. “The one takeaway is that buffalo fish do not conform to preconceived notions,” says study leader Alec Lackmann, a fish expert at the University of Minnesota. Buffalo fish can go decades between successful reproductions because they require very specific environmental conditions — most of which are still unknown — to procreate. That’s why the fish evolved to live so long: It’s an evolutionary adaptation to account for long periods without breeding, according to Lackmann. In Saskatchewan, where buffalo fish can go up to 50 years without producing offspring, the fish only attempt to spawn within a narrow range of water-level fluctuations that may rarely occur. A 2021 study on bigmouth buffalo fish confirmed that older fish are less stressed and have stronger immunity than younger ones. Older individuals could fight off bacteria better than younger animals. Not only that, the elderly fish had a lower ratio of neutrophils to lymphocytes in the blood, an indication of lower stress levels. “They are still advancing into prime condition at a century old, which is astonishing,” Lackmann says. (SD-Agencies) Words to Learn 相關(guān)詞匯 【顛覆】diānfù upend affect to the point of being upset or flurried 【安樂(lè)死】ānlèsǐ euthanize kill in a relatively painless way for reasons of mercy 科學(xué)家最近證實(shí)，生活在美國(guó)亞利桑那州東部一個(gè)偏遠(yuǎn)沙漠湖里的大多數(shù)水牛魚(yú)都超過(guò)100歲了。 這一發(fā)現(xiàn)建立在其他研究的基礎(chǔ)上，此前的研究已顛覆了人們對(duì)水牛魚(yú)的看法，這種淡水魚(yú)原產(chǎn)于北美，包括五個(gè)分支。 幾年前，科學(xué)家還以為這些栗色、藍(lán)色的魚(yú)只能活到20多歲。然而，一項(xiàng)2019年的研究揭示，大口水牛魚(yú)能活到112歲，是已知最古老的淡水硬骨魚(yú)，屬于射線鰭魚(yú)類(lèi)，全球范圍內(nèi)約有12000種。今年1月，研究人員宣布在加拿大薩斯喀斯溫省發(fā)現(xiàn)了一只127歲的大口水牛魚(yú)。 發(fā)表在《科學(xué)報(bào)告》上的研究證實(shí)，又有兩種水牛魚(yú) ——小口水牛魚(yú)和黑水牛魚(yú) —— 可以活過(guò)一百歲，這使其成為除了海洋巖魚(yú)（鯛魚(yú)）之外，唯一已知擁有三種能活百年物種的動(dòng)物屬。 2018年7月至2023年7月，幾十名垂釣者在亞利桑那州的阿帕契湖捕獲了222條水牛魚(yú)。其中23條被安樂(lè)死后捐贈(zèng)給研究小組，科學(xué)家摘取并分析了魚(yú)的微小耳石來(lái)估計(jì)它們的年齡。耳石是碳酸鈣結(jié)晶，讓魚(yú)類(lèi)能夠聽(tīng)到和感知水中的振動(dòng)，就像樹(shù)木的年輪，耳石每年都會(huì)形成新的一層。 研究者們估算三種研究物種都有個(gè)體年齡達(dá)到百歲以上。 此外，研究表明，水牛魚(yú)八九十歲時(shí)仍能保持最佳身體狀態(tài)。 明尼蘇達(dá)大學(xué)魚(yú)類(lèi)專(zhuān)家、研究負(fù)責(zé)人亞歷克?拉克曼說(shuō)：“結(jié)論是，水牛魚(yú)打破了我們的常規(guī)認(rèn)識(shí)。” 因?yàn)閷?duì)環(huán)境的要求特殊，水牛魚(yú)可能數(shù)十年才能成功繁殖一次，具體需要什么條件，基本上還是個(gè)謎。這就是水牛魚(yú)長(zhǎng)壽的原因： 拉克曼認(rèn)為，長(zhǎng)壽是針對(duì)繁殖間隔長(zhǎng)的進(jìn)化適應(yīng)策略。 薩斯喀斯溫省的水牛魚(yú)甚至50 年不產(chǎn)后代，它們只在罕見(jiàn)的水位低波動(dòng)窗口產(chǎn)卵。 2021年一項(xiàng)關(guān)于大口水牛魚(yú)的研究證實(shí)：年長(zhǎng)比年輕的水牛魚(yú)壓力更小，免疫力更強(qiáng)。 年老比年輕的個(gè)體能更好地對(duì)抗細(xì)菌。不僅如此，老年魚(yú)的血液中中性粒細(xì)胞/淋巴細(xì)胞的比例更低，這是壓力水平較低的表現(xiàn)。拉克曼說(shuō)：“它們?cè)诎贇q年紀(jì)仍處于身體最佳狀態(tài)，令人驚訝。” (Translated by Debra) | 