Corals Spin Tiny Vortices to Get Oxygen, but Not if It’s Too Hot

Fluorescent, oxygen-reactive nanoparticles are caught in swirls of water created by a coral’s cilia.

荧光的、与氧反应的纳米颗粒被捕获在珊瑚纤毛产生的水漩涡中。

Cesar Pacharres/colored by Quanta Magazine

Cesar Pacharres/广达杂志上色

At first glance, corals present as little more than colorful rocks — piles of lobes, stalagmites, and branches poking out from the seafloor.

乍一看，珊瑚只不过是色彩缤纷的岩石——成堆的裂片、石笋和从海底伸出的树枝。

They are anything but.

他们绝不是。

Corals are complex creatures that form enduring colonies, and just like other animals they need oxygen to live.

珊瑚是一种复杂的生物，可以形成持久的群体，就像其他动物一样，它们需要氧气才能生存。

Across the living surface of coral, a frantic dance of survival takes place, invisible to our eyes and unknown to science before 2014.

在珊瑚的生命表面，一场疯狂的生存之舞正在上演，但在 2014 年之前，我们的肉眼看不见，科学也不为人所知。

The tiny dancers are hairlike cilia, and new research into these microscopic structures is revealing just how active corals are in determining their own fate.

这些微小的舞者是毛发状的纤毛，对这些微观结构的新研究揭示了珊瑚在决定自己的命运方面是多么活跃。

Corals aren’t fortunate enough to have a consistent supply of oxygen, and they can’t change location to seek it out.

珊瑚不够幸运，无法持续供应氧气，而且它们无法改变位置来寻找氧气。

During the day, the tiny polyps that make up a coral colony get plenty of oxygen from the symbiotic algae that photosynthesize within their tissues.

白天，构成珊瑚群落的微小息肉从组织内进行光合作用的共生藻类中获取大量氧气。

But at night that process stops, and a coral polyp’s only source of oxygen is the water around it.

但到了晚上，这个过程就会停止，珊瑚虫唯一的氧气来源就是它周围的水。

Then it’s do or die for the cilia.

那么对于纤毛来说就是生死存亡。

Using mechanisms scientists are still trying to understand, the cilia wave around to generate fast-moving vortices of water that circulate oxygen to the coral’s outer tissues, in addition to helping keep the colonies free of sediment.

利用科学家们仍在试图了解的机制，纤毛四处波动，产生快速移动的水涡流，将氧气循环到珊瑚的外部组织，此外还有助于保持珊瑚群免受沉积物的影响。

A study published in Science in May 2026 provides new insight into how organisms with no brain or musculoskeletal system can generate and regulate this process — and what happens when the water around them warms up.

2026 年 5 月在《科学》杂志上发表的一项研究为没有大脑或肌肉骨骼系统的生物体如何产生和调节这一过程以及当它们周围的水变暖时会发生什么提供了新的见解。

Warmer water naturally carries less oxygen, which prompts corals to move their cilia faster and faster, as if gasping for breath.

温暖的水自然携带较少的氧气，这促使珊瑚的纤毛移动得越来越快，就像喘气一样。

Above a certain temperature, the system starts to work against itself; the furious beating of cilia uses up any oxygen the coral’s tissues can absorb, and then the polyps can suffocate in the less oxygenated water.

当温度超过一定值时，系统就会开始自相矛盾。纤毛的剧烈跳动耗尽了珊瑚组织可以吸收的氧气，然后珊瑚虫就会在含氧量较低的水中窒息。

Biophysicists, marine biologists, mathematicians, and modelers are now collaborating to better understand the physiological and hydrodynamic forces at work, and how they correlate with bleaching patterns, coral disease, and mass die-offs.

生物物理学家、海洋生物学家、数学家和建模师现在正在合作，以更好地了解起作用的生理和水动力，以及它们与漂白模式、珊瑚疾病和大规模死亡之间的关系。

This dynamic picture is somewhat new to scientists, who have long used corals’ symbiotic algal partners as indicators of their health.

这种动态图景对于科学家来说有些新鲜，他们长期以来一直使用珊瑚的共生藻类伙伴作为其健康状况的指标。

Cilia may serve as a more direct signal, said Rachel Alderdice , a marine biologist who studies coral stress biomarkers and genomics at the University of Konstanz in Germany and was not involved in the research.

德国康斯坦茨大学研究珊瑚应激生物标志物和基因组学的海洋生物学家 Rachel Alderdice 表示，纤毛可能是一个更直接的信号，她没有参与这项研究。

“It’s these finer details that could help us understand why some corals bleach and others don’t, [even when] they sit right beside each other.”

“正是这些更精细的细节可以帮助我们理解为什么有些珊瑚会白化，而另一些珊瑚却不会白化，即使它们彼此相邻。”

Every coral colony is cushioned by a thin boundary layer of water whose movement is slowed by friction at the coral’s surface.

每个珊瑚群落都被一层薄薄的水边界层所缓冲，其运动因珊瑚表面的摩擦而减慢。

Researchers assumed that corals were passive with respect to the slow-moving boundary layer, simply relying on natural diffusion through it to provide nutrients and oxygen.

研究人员认为，珊瑚对于缓慢移动的边界层是被动的，仅依靠通过边界层的自然扩散来提供营养和氧气。

A colony of Porites lutea , a stony coral, continues to grow slowly in waters off the Samoan Islands.

黄滨珊瑚（一种石珊瑚）群落在萨摩亚群岛附近的水域中继续缓慢生长。

Then, in 2014, a team from the Massachusetts Institute of Technology and the Weizmann Institute of Science published a groundbreaking study showing that coral cilia interact with the boundary layer by rapidly whipping about to generate swirls of fresh, oxygenated seawater.

然后，在 2014 年，麻省理工学院和魏茨曼科学研究所的一个团队发表了一项开创性的研究，表明珊瑚纤毛与边界层相互作用，通过快速鞭打产生新鲜的含氧海水漩涡。

Until a decade ago, scientists thought of these cilia merely as brooms that move mucus and sweep away waste particles and other debris.

直到十年前，科学家们还认为这些纤毛只是扫帚，可以移动粘液并清除废物颗粒和其他碎片。

The research not only modeled the tiny vortices created by the cilia for the first time, but also revealed the cilia’s importance for survival and metabolism.

该研究不仅首次模拟了纤毛产生的微小涡流，而且揭示了纤毛对于生存和新陈代谢的重要性。

At first, the microbiologist and environmental engineer Orr Shapiro , who led the 2014 work at MIT as a postdoctoral fellow, was interested in how microbes that infect corals and cause disease follow concentration gradients, a process called chemotaxis.

微生物学家兼环境工程师奥尔·夏皮罗 (Orr Shapiro) 最初对感染珊瑚并引起疾病的微生物如何遵循浓度梯度（这一过程称为趋化性）感兴趣。2014 年，奥尔·夏皮罗在麻省理工学院担任博士后研究员，领导了这项工作。

Under the microscope, he noticed something weird: In the boundary layer, particles were swirling around and mixing together — not at all like the passive diffusion he had been expecting.

在显微镜下，他注意到一些奇怪的东西：在边界层中，粒子旋转并混合在一起——完全不像他所期待的被动扩散。

It could be oxygen that’s been the smoking gun all along.

氧气可能一直是确凿的证据。

David Suggett, King Abdullah University of Science and Technology

大卫·苏吉特，阿卜杜拉国王科技大学

“That was to me, and I think later on to the entire field, sort of a paradigm shift,” said Shapiro, now a researcher at the Volcani Institute in Israel.

“这对我来说，以及后来对整个领域来说，都是一种范式转变，”夏皮罗说，他现在是以色列火山研究所的研究员。

It became clear that the boundary layer wasn’t static, but rather a dynamic zone, and one where cilia were creating their own turbulence.

很明显，边界层不是静态的，而是一个动态区域，纤毛在其中创造自己的湍流。

The realization inspired Shapiro’s team to go off on a tangent, mapping the flow of oxygen to coral tissues via cilia.

这一认识启发夏皮罗的团队采取了另一种做法，绘制了氧气通过纤毛流向珊瑚组织的图谱。

“It really transformed how we understand this [micro]environment, because suddenly the diffusion is no longer really important,” Shapiro said.

“这确实改变了我们对这种[微]环境的理解，因为突然间扩散不再那么重要了，”夏皮罗说。

Diffusion is the default route for nutrients traveling through water, but it’s painfully slow.

扩散是营养物质在水中传播的默认途径，但速度非常慢。

It can take as long as four minutes for oxygen to travel just 1 millimeter.

氧气传播 1 毫米可能需要长达四分钟的时间。

That’s why the fast-moving flows created by cilia are so important: because naturally flowing water slows down near the coral’s surface, and corals consume oxygen faster than diffusion can supply it.

这就是为什么纤毛产生的快速流动如此重要：因为自然流动的水在珊瑚表面附近会减慢，而珊瑚消耗氧气的速度比扩散提供氧气的速度快。

It is a system that delivers enough oxygen, despite the cilia’s energy consumption.

尽管纤毛消耗能量，但该系统仍能提供足够的氧气。

But there’s a downside: Oxygen dwindles as temperature climbs.

但也有一个缺点：随着温度升高，氧气会减少。

That’s when corals run into trouble.

这就是珊瑚遇到麻烦的时候。

Scientists have a clear understanding of one thing that happens to corals when water gets too hot: bleaching.

科学家们清楚地了解当水变得太热时珊瑚会发生的一件事：白化。

As water temperatures rise, a coral’s symbiotic algae become stressed and release molecules that are toxic to the coral in large quantities.

随着水温升高，珊瑚的共生藻类会受到压力，并释放大量对珊瑚有毒的分子。

To protect itself, the coral expels its own algae — a primary food, energy, and oxygen source — and soon loses its color.

为了保护自己，珊瑚会排出自己的藻类（主要食物、能量和氧气来源），并很快失去颜色。

It’s a slow death and an increasingly common occurrence as heat waves sweep across the world’s reefs.

随着热浪席卷世界各地的珊瑚礁，这种缓慢的死亡现象也越来越常见。

But sometimes, some corals on a reef bleach while others don’t, and in other cases corals under heat stress die without expelling their algae.

但有时，珊瑚礁上的一些珊瑚会白化，而另一些珊瑚则不会，而在其他情况下，珊瑚在热应激下会死亡而没有排出藻类。

An international team of microbiologists, engineers, and physiologists was eager to understand how heat affects cilia, and whether this could explain different types of coral death.

一个由微生物学家、工程师和生理学家组成的国际团队渴望了解热量如何影响纤毛，以及这是否可以解释不同类型的珊瑚死亡。

In the experiment, researchers exposed stony coral to various water temperatures.

在实验中，研究人员将石珊瑚暴露在不同的水温下。

Fluorescent nanoparticles revealed the flow of oxygenated water.

荧光纳米粒子揭示了含氧水的流动。

“We’re living in a world right now of extreme scenarios,” said Cesar Pacherres , a co-author of the new study and a marine biologist at the University of Copenhagen who studies fluid dynamics.

这项新研究的合著者、哥本哈根大学研究流体动力学的海洋生物学家塞萨尔·帕切雷斯（Cesar Pacherres）说：“我们现在生活在一个充满极端情况的世界。”

As marine heat waves become more common, and as a particularly strong El Niño year threatens to catalyze a fifth global bleaching event in late 2026, “corals can experience an increase in temperature of several degrees in a time frame of a few hours,” Pacherres said.

Pacherres 表示，随着海洋热浪变得越来越普遍，特别强烈的厄尔尼诺年可能会在 2026 年底引发第五次全球白化事件，“珊瑚可能会在几个小时内经历温度升高几度的情况”。

To explore heat’s impact on cilia, the team ran a series of 24-hour experiments.

为了探索热量对纤毛的影响，研究小组进行了一系列 24 小时的实验。

They exposed aquarium-raised stony coral called Porites lutea to incrementally higher water temperatures up to 39 degrees Celsius (more than 102 degrees Fahrenheit) — an extreme scenario, but one that could occur.

他们将水族箱饲养的黄滨石珊瑚暴露在逐渐升高的水温中，最高可达 39 摄氏度（超过 102 华氏度）——这是一种极端情况，但可能会发生。

They kept the tanks dark to better observe how cilia transport oxygen when algae aren’t producing any.

他们将水箱保持黑暗，以便更好地观察当藻类不产生氧气时纤毛如何输送氧气。

Every hour, the researchers recorded the microscopic cilia with a high-speed camera to capture how frequently they moved as they were exposed to warmer and warmer water.

每小时，研究人员都会用高速摄像机记录微小纤毛，以捕捉它们暴露在越来越温暖的水中时移动的频率。

The team also used a technology called SensPIV to track oxygen flow.

该团队还使用了一种名为 SensPIV 的技术来跟踪氧气流量。

Fluorescent, oxygen-reactive nanoparticles “traced” the water swirls, creating a vivid map of how oxygen concentrations corresponded to the cilia’s vortices.

荧光、与氧反应的纳米颗粒“追踪”了水的漩涡，创建了一幅生动的地图，显示氧浓度如何与纤毛的漩涡相对应。

Visualizing the movement of oxygen was key to the team’s findings.

可视化氧气的运动是该团队研究结果的关键。

In warmer water, corals burned energy faster, which increased their demand for oxygen — prompting the cilia to dance faster.

在温暖的水中，珊瑚燃烧能量的速度更快，这增加了它们对氧气的需求，促使纤毛舞得更快。

But there’s only so much dissolved oxygen available in the surrounding water, and as temperatures climbed, the cilia started to send oxygen-deficient water toward the coral in their frenzy.

但周围的水中只有这么多溶解氧，随着温度的上升，纤毛开始疯狂地将缺氧的水输送到珊瑚上。

“The oxygen demand of the coral increased faster than the increased swirling of the water,” said co-author Michael Kühl , a marine microbiologist at the University of Copenhagen.

哥本哈根大学海洋微生物学家、论文合著者迈克尔·库尔 (Michael Kühl) 表示：“珊瑚的需氧量增长速度快于海水漩涡的增长速度。”

When the water approached 37 degrees Celsius (the temperature of the human body), the cilia started to slow down.

当水接近37摄氏度（人体温度）时，纤毛开始减慢。

Past 39 degrees Celsius, they shut down altogether, and the coral died.

当温度超过 39 摄氏度时，它们完全停止活动，珊瑚也死亡了。

These were the findings they reported in Science in May 2026.

这些是他们于 2026 年 5 月在《科学》杂志上报道的发现。

Coral cilia move normally in water heated to 27 degrees Celsius (left).

珊瑚纤毛在加热至 27 摄氏度的水中正常移动（左）。

At 39 degrees Celsius (right), cilia motion slowed and eventually stopped.

在 39 摄氏度（右）时，纤毛运动减慢并最终停止。

Pacherres cautioned against interpreting these temperature limits as a standard threshold; each species of coral is adapted to its own range of daily temperature fluctuations.

帕切雷斯警告不要将这些温度限制解释为标准阈值；每种珊瑚都适应自己的每日温度波动范围。

Even so, climate change has started to push many corals toward their respective limits, with record-high surface water temperatures nearing 38 degrees Celsius in places such as Florida.

即便如此，气候变化已开始将许多珊瑚推向各自的极限，佛罗里达州等地的地表水温创历史新高，接近 38 摄氏度。

Why the cilia move faster in hotter water remains a mystery.

为什么纤毛在热水中移动得更快仍然是个谜。

Perhaps seawater’s viscosity — which decreases as temperature increases, making the water thinner —affects ciliary movements, Shapiro said.

夏皮罗说，也许海水的粘度——随着温度的升高而降低，使水变得更稀——会影响纤毛的运动。

Corals lack a central nervous system and brain, but they do have neurons — inside what’s called a nerve net — to process sensory information.

珊瑚缺乏中枢神经系统和大脑，但它们确实有神经元（位于所谓的神经网络内）来处理感官信息。

Perhaps the coral senses heat or lack of oxygen, and some biological mechanism then triggers the faster beating.

也许珊瑚感觉到了热量或缺氧，然后某种生物机制触发了更快的跳动。

“It’s physics, biology, engineering, all mixed up together, which is what makes it really interesting,” he said.

“这是物理学、生物学、工程学，所有这些都混合在一起，这才是它真正有趣的原因，”他说。

Scientists are now investigating cilia physiology and the boundary layer as a whole.

科学家们现在正在研究纤毛生理学和整个边界层。

“It’s much more complex than we thought,” Shapiro said.

“这比我们想象的要复杂得多，”夏皮罗说。

In another paper co-authored by Pacherres and Kühl in May 2026, they found that cilia’s vortices resemble corkscrews.

在 Pacherres 和 Kühl 于 2026 年 5 月共同撰写的另一篇论文中，他们发现纤毛的漩涡类似于开瓶器。

The turbulence pushes unwanted particles away from the coral’s surface while redirecting nutrients toward polyps’ mouths.

湍流将不需要的颗粒推离珊瑚表面，同时将营养物质重新导向珊瑚虫的嘴。

Under a microscope it’s possible to see the density and arrangement of cilia on a coral surface.

在显微镜下可以看到珊瑚表面纤毛的密度和排列。

The cilia on each polyp, they found, are arranged in hexagonal units that keep ciliary movement streamlined, which helps explain how cilia can coordinate their movement to produce predictable swirls.

他们发现，每个息肉上的纤毛都排列成六角形单元，使纤毛运动保持流线型，这有助于解释纤毛如何协调其运动以产生可预测的漩涡。

“It demonstrates that coral skeletal architecture and living tissue are functionally integrated,” Pacherres said.

“它表明珊瑚骨骼结构和活组织在功能上是整合的，”帕切雷斯说。

Combined, the studies recontextualize how ciliary movement, previously overlooked, gives corals some stability and buffers them against environmental change, he said.

他说，综合起来，这些研究重新审视了以前被忽视的纤毛运动如何赋予珊瑚一定的稳定性并缓冲它们免受环境变化的影响。

The relationship between cilia and bleaching remains ambiguous, said Alderdice, who was not involved in the studies.

没有参与这项研究的阿尔德迪斯说，纤毛和漂白之间的关系仍然不明确。

But testing cilia under bleaching conditions without heat — by using red light, for example, which can also trigger bleaching — would help answer this question.

但是在没有加热的漂白条件下测试纤毛——例如使用红光，这也可以引发漂白——将有助于回答这个问题。

Scientists knew from the 2014 work that cilia help corals self-ventilate when water flow is low, said David Suggett , a marine biologist at King Abdullah University of Science and Technology who wasn’t involved in the research.

阿卜杜拉国王科技大学海洋生物学家 David Suggett（未参与这项研究）表示，科学家们从 2014 年的研究中得知，当水流量较低时，纤毛可以帮助珊瑚进行自我通风。

“But until this point, we had been focusing on molecular and metabolic machinery” to understand how corals evolved to deal with low-oxygen conditions, he said.

“但到目前为止，我们一直专注于分子和代谢机制”，以了解珊瑚如何进化以应对低氧条件，他说。

“We hadn’t really appreciated that there are these behavioral-physiological mechanisms at play.”

“我们并没有真正意识到这些行为生理机制在起作用。”

For Suggett, the research raises a critical question: What does this say about how corals will deal with future climates?

对于苏吉特来说，这项研究提出了一个关键问题：这对珊瑚将如何应对未来的气候有何说明？

Sometimes, corals of a single reef don’t bleach evenly, with some individuals dying off while their neighbors persist.

有时，单个珊瑚礁的珊瑚不会均匀白化，一些个体死亡，而它们的邻居却持续存在。

In new research led by Suggett’s colleague Tadd Truscott, marine biologists are finding that these patchy bleaching patterns are correlated with areas of reduced water flow — areas therefore receiving less oxygen.

在苏吉特的同事塔德·特拉斯科特领导的新研究中，海洋生物学家发现这些斑片状白化模式与水流减少的区域相关，因此这些区域接收的氧气较少。

Next, Kühl and Pacherres’ team wants to test corals under different conditions — especially under normal light-dark cycles — and to better understand the mechanism driving ciliary beating.

接下来，Kühl 和 Pacherres 的团队希望在不同条件下测试珊瑚——尤其是在正常的光暗循环下——并更好地了解驱动纤毛跳动的机制。

Is it a molecular process that activates their movement?

是一个分子过程激活了它们的运动吗？

The physics of warmer seawater?

海水变暖的物理原理？

A bit of both, or something else?

两者兼而有之，还是别的什么？

It’s only in the past decade that scientists have realized the role of deoxygenation in coral health, Suggett said.

苏吉特说，直到过去十年，科学家们才意识到脱氧在珊瑚健康中的作用。

Ocean acidification took center stage as the primary concern for corals in the early 2000s.

2000 年代初，海洋酸化成为珊瑚关注的首要问题。

In hindsight, deoxygenation was a much bigger issue, he said.

他说，事后看来，脱氧是一个更大的问题。

The new research suggests that deoxygenation, not just bleaching, is a fatal threat to corals resulting from a hotter climate.

新的研究表明，气候变暖导致的珊瑚脱氧，而不仅仅是白化，是一个致命的威胁。

“We’re playing massive catch-up,” Suggett said.

“我们正在大力追赶，”苏吉特说。

“The amount of information we’re gathering quickly is demonstrating just what a problem for corals it is — so much so that we’re starting to really revisit long-standing paradigms of the role of other environmental factors, like temperature and light, where in fact, it could be oxygen that’s been the smoking gun all along.”

“我们快速收集的大量信息表明珊瑚面临着多大的问题，以至于我们开始真正重新审视温度和光线等其他环境因素的长期作用范式，事实上，氧气一直是确凿无疑的证据。”

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《Quanta》杂志对评论进行审核，以促进知情、实质性、文明的对话。

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版主在正常工作时间（纽约时间）有工作人员，并且只能接受英文评论。