Inside the fascinating world of India’s blind cave-dwelling fish
探秘印度盲眼洞穴鱼的神奇世界
Two years ago, zoologist Khlur Baiaineh Mukhim spotted something intriguing in a stream in a remote underground cave in India’s north-eastern Meghalaya state.
两年前，动物学家 Khlur Baiaineh Mukhim 在印度东北部梅加拉亚邦一处偏远地下洞穴的溪流中发现了令人着迷的生物。
It was a fish he had never seen before, with long barbels – the whisker-like protrusion around a fish’s mouth – yellowish-green in colour and, most importantly, with eyes.
那是一种他从未见过的鱼，长着长长的触须——鱼类嘴部周围类似胡须的突起——呈黄绿色，最重要的是，它拥有眼睛。
Cave-dwelling fish, or species of fish that live exclusively in caves, usually don’t have eyes, as they have adapted to living in darkness, which is why the fish Mr Mukhim spotted stood out to him.
穴居鱼类，即完全生活在洞穴中的鱼种，通常没有眼睛，因为它们已适应黑暗环境生存，这正是 Mukhim 先生发现的这条鱼引起他注意的原因。
Researchers in Meghalaya now say it is a brand new species of fish, one that has adapted to living above as well as under the ground – a unique characteristic among cave-dwelling species.
梅加拉亚邦的研究人员表示，这确属鱼类新物种，其独特之处在于既能适应地表生活又能栖居地下——这在穴居物种中实属罕见。
Their findings were published earlier this month in the latest issue of the Journal of Fish Biology, a leading peer-reviewed publication on fish research.
这项研究成果本月早些时候发表于鱼类研究领域的权威期刊《鱼类生物学杂志》最新一期。
在克雷姆·马维姆布因洞穴发现的厚尾南鳅
The researchers have named the fish Schistura ‘densiclava’ after the thick black stripe on its tail.
研究人员根据该鱼尾部醒目的黑色条纹，将其命名为”厚尾南鳅”（Schistura densiclava）。
They say that the species is endemic to the cave it was discovered in – Krem Mawjymbuin – in the eastern Khasi Hills, and has been found to exist in both water pools 60m (196ft) deep inside the cave, as well as a nearby stream above ground.
研究人员表示，该物种是发现地——东卡西丘陵 Krem Mawjymbuin 洞穴的特有种，既存在于洞穴内 60 米（196 英尺）深的水潭中，也栖息于地表附近的溪流里。
Dandadhar Sarma, a professor of zoology and one of the researchers of the study, says that the environment inside the cave is harsh, where temperatures drop to 18C (64.4F) – the ideal temperature for tropical fish to survive is much higher – and oxygen levels are extremely low.
研究团队成员、动物学教授丹达达尔·萨尔玛指出，洞穴内部环境严酷，温度低至 18 摄氏度（64.4 华氏度）——远低于热带鱼类的理想生存温度，且氧气含量极低。
“So it’s remarkable that the fish can adapt to both – harsh subterranean conditions as well as more favourable surface conditions,” Mr Sarma says.
“这种鱼类能同时适应严苛的地下环境和更适宜的地表环境，实在令人惊叹，”萨尔玛教授说道。
Schistura densiclava is the sixth cave-dwelling species of fish that has been discovered in Meghalaya over the past two to three decades, but the only one which has been found to show this ability to adapt to two very different kinds of environments.
施氏鳅（Schistura densiclava）是过去二三十年间在梅加拉亚邦发现的第六种洞穴鱼类，但它是目前唯一被证实能适应两种截然不同环境的物种。
The state is known to have some of the most complex cave systems in the world but many of its estimated 1,500 to 1,700 limestone and sandstone caves remain unexplored, as they are located in remote, forested regions that are challenging to access.
该邦以拥有全球最复杂的洞穴系统而闻名，但其约 1500 至 1700 个石灰岩和砂岩洞穴中仍有大量未经勘探，这些洞穴位于偏远林区，通行极为困难。
These cave networks are home to numerous animal species that display fascinating evolutionary characteristics but they remain largely unknown because of insufficient research, Mr Sarma says.
萨尔玛先生表示，这些洞穴网络栖息着众多具有迷人进化特征的动物物种，但由于研究不足，它们大多仍不为人知。
Over the past five years, a team of researchers from the state, funded by the federal government, have been systematically exploring Meghalaya’s vast network of caves to locate and document new species of fish living inside them.
过去五年间，一支由联邦政府资助的梅加拉亚邦本土研究团队，一直在系统性地探索该邦庞大的洞穴网络，以寻找并记录生活在其中的新鱼类物种。
In 2019, the research team discovered Neolissochilus pnar, the largest cave-dwelling fish species in the world, Mr Sarma says.
萨尔玛称，2019 年该研究团队发现了世界上最大的穴居鱼类物种——尼洛鱼（Neolissochilus pnar）。
The fish was found inside the Krem Umladaw cave in the western Jaintia Hills in a deep pond hundreds of metres below the ground.
这种鱼类发现于西贾因蒂亚山区 Krem Umladaw 洞穴内，位于地下数百米深的池塘中。
克雷姆·乌姆拉道洞穴入口
Mr Mukhim, who is part of the team and has undertaken dozens of cave expeditions, says that cave-dwelling fish display evolutionary traits that are as fascinating as the those displayed by animals living at the Earth’s poles or deep inside its oceans.
作为团队一员并参与过数十次洞穴探险的 Mukhim 先生表示，穴居鱼类展现出的进化特征，与地球两极或深海生物所呈现的特质同样令人着迷。
“Cave ecosystems are one of the harshest environments to live in,” he says.
“洞穴生态系统是最恶劣的生存环境之一，”他说道。
“These fish usually live in perpetual darkness, stagnant, shallow water pools with dangerously low oxygen levels and sometimes, go for months with little to no food.”
“这些鱼类通常生活在永恒的黑暗中，栖息于氧气含量极低、近乎停滞的浅水池中，有时甚至数月都几乎没有食物。”
Nature has helped them survive by doing away with the unwanted and strengthening what’s necessary for survival.
大自然通过摒弃多余之物、强化生存必需，帮助它们得以存活。
Consequently, they’ve lost their eyesight and ability to produce colourful pigments, which would otherwise be a needless waste of energy inside a pitch-dark cave.
因此，它们丧失了视力和产生彩色色素的能力——在漆黑一片的洞穴中，这些功能只会造成无谓的能量消耗。
Instead, they have a sharper sense of taste and smell, and sensory organs on their skin help them detect vibrations to navigate the substrate and avoid predators.
相反，它们拥有更敏锐的味觉和嗅觉，皮肤上的感觉器官能帮助探测振动，从而在基质中导航并躲避捕食者。
Their sources of food include only what’s available inside the cave, like leaf debris and marine organisms flushed in by seasonal floods, and even bat excreta.
它们的食物来源仅限于洞穴内的可用资源，如季节性洪水冲入的落叶碎屑和海洋生物，甚至包括蝙蝠排泄物。
And within this extremely harsh environment, these cave-dwelling fish species live out their lives, some living up to a decade, and even produce offspring.
在这种极端恶劣的环境中，这些穴居鱼类终其一生，有些寿命可达十年之久，甚至还能繁衍后代。
Remarkably, their offspring are born with eyesight – a feature that links them to the surface-dwelling ancestors from which they’ve evolved – and gradually, they lose their eyesight as they age.
值得注意的是，它们的后代出生时具有视力——这一特征将它们与进化前的陆栖祖先联系起来——随着年龄增长，视力会逐渐退化消失。
新发现的洞穴鱼类物种 Neolissochilus pnar，为目前全球体型最大的穴居鱼类
But searching for these fish is no easy task.
但寻找这些鱼类绝非易事。
It involves rappelling down hundreds of meters into cavernous holes in the earth, squeezing through tiny tunnels with little oxygen and wading through pools filled with creatures yet unknown in pitch darkness.
探险者需要沿绳索垂降数百米深入地下洞穴，在氧气稀薄的狭窄隧道中艰难穿行，并在漆黑的水潭中涉水前行，那里栖息着许多尚未被人类认知的生物。
“Our headlights are the only source of light,” Mr Mukhim says.
“我们的头灯是唯一的光源，”穆克希姆先生说。
Catching fish involves squatting near pools for hours, and swiftly sweeping up the skittish creatures in a net as they present themselves.
捕鱼时需要在水潭边蹲守数小时，当这些胆小的生物现身时迅速用网兜将其捕获。
Mr Mukhim, who has been studying fish found in the caves of Meghalaya for over a decade, says that there’s a need to study these species as that is the only way we will be able to conserve them.
研究梅加拉亚邦洞穴鱼类已逾十年的穆克希姆表示，必须对这些物种进行研究，因为这是保护它们的唯一途径。
“Once a species is wiped out, you can never bring them back,” Mr Mukhim says.
“一个物种一旦灭绝，就再也无法挽回，”穆基姆先生说。
“It’s painful to think that an entire ecosystem in our midst, one of the most fascinating ones, has been studied so little,” he adds.
“想到我们身边最迷人的生态系统之一竟然研究得如此之少，这令人痛心，”他补充道。
“It’s time we paid a little more attention to these cave-dwelling marvels of nature.”
“是时候我们该多关注这些洞穴栖息的自然奇观了。”