Ignored by the World, These Tiny Creatures Are Silently Saving the Planet But Not for Long

Microscopic ocean animals known as zooplankton are quietly preventing global catastrophe by storing carbon in the deep sea. But climate change and commercial threats may soon destroy this natural defense. 

They are not penguins, not whales, nor any of Antarctica’s usual poster animals. In fact, most people only know them as fish food. But new research shows these tiny, jelly-bodied animals—zooplankton—are the unsung heroes of Earth’s climate survival.

Drifting quietly through the freezing waters of the Southern Ocean, these creatures gorge on carbon, grow fat, and then vanish into the dark, cold abyss of the ocean—taking the planet’s carbon emissions with them. This natural carbon storage process is so powerful that it’s estimated to lock away the equivalent emissions of 55 million petrol-powered cars annually. But as with most of nature’s miracles, human activity is threatening to unravel this delicate balance.

Nature’s Secret Carbon Guardians

In the spring, zooplankton like copepods, krill, and salps rise to the ocean surface to feast on microscopic algae called phytoplankton. The carbon consumed is stored as fat within their translucent bodies. Then, in a mysterious but calculated descent, these creatures sink hundreds or even thousands of meters below the surface and spend the winter burning their fat reserves.

Antarctic krill (50-60mm) with green guts showing they've recently eaten algae

That fat—converted carbon is released in deep ocean layers, where it remains trapped for decades or even centuries. This phenomenon, known as the seasonal vertical migration pump, effectively locks away 65 million tonnes of carbon annually at depths unreachable by sunlight and atmospheric cycles. Without this, the Earth’s atmosphere would be significantly warmer than it is today.

The Tiny Heroes With Giant Impact

While the role of ocean creatures in climate regulation was known, the scale of this carbon lock-down stunned scientists. Copepods, only 4mm in size, turned out to be the most efficient carbon sequesters. Their lifestyle is bizarre—spending most of their lives asleep at unimaginable depths, occasionally rising for a seasonal feast.

According to Prof Daniel Mayor and Dr Jennifer Freer, who led the latest study on board the Sir David Attenborough polar ship, this hidden process has gone underappreciated for nearly a century. Microscopic images from their expedition show fat-filled zooplankton, vibrant with green and orange pigments—living batteries storing the Earth’s carbon load.

On the Brink of Collapse

But just as their monumental role has been uncovered, zooplankton are facing growing threats. Rising ocean temperatures, changes in water layers, and extreme weather events—hallmarks of climate change—are disrupting their delicate life cycles.

Female copepods (4mm) with cigar-shaped fat stores in their bodies

Even worse, commercial krill fishing is accelerating. In 2020 alone, nearly half a million tonnes of krill were harvested. Though legal under international marine law, environmentalists and scientists alike are sounding alarms. If zooplankton populations collapse, the Southern Ocean’s carbon sequestration engine may stall—with devastating global consequences.

A Warning for Climate Models

The findings, published in the journal Limnology and Oceanography, suggest current climate models may be underestimating the Southern Ocean's role in carbon absorption. Scientists argue that ignoring this “biological pump” creates blind spots in forecasting how fast the planet will heat.

This copepod has hair-like arms for feeding

According to co-author Prof Angus Atkinson, without zooplankton, the world’s atmospheric CO2 levels would be almost double what they are now. In a time of climate emergency, these minuscule creatures are not just important—they’re indispensable.

Yet they remain invisible in policy discussions, overlooked in conservation funding, and absent from most public climate narratives.

You can also read: The Forgotten Wildcat,   A Silent Crisis in the Skies,   Webb Telescope,   The Bird That Almost Vanished,   The Egyptian Vulture,    the King Vulture,   The Most Dangerous Jungle