Scientists discover the world's largest coral — so big it can be seen from space

The world’s largest coral has just been discovered in the southwest Pacific Ocean. (Steve Spence/National Geographic Pristine Seas)

It’s more than 100 feet long, at least 300 years old and visible from space. The world’s largest coral has just been discovered in the southwest Pacific Ocean, scientists announced Wednesday.

The mega coral was spotted during a scientific expedition launched by the National Geographic Pristine Seas program in October to study ocean health in the Solomon Islands.

It’s three times larger than the previous record-breaker in American Samoa, according to Pristine Seas, and longer than a blue whale, the planet’s biggest animal.

Unlike a reef, which consists of many colonies, this coral is a single specimen that has grown continuously for centuries.

“Just when we think there is nothing left to discover on planet Earth, we find a massive coral made of nearly 1 billion little polyps, pulsing with life,” said Enric Sala, National Geographic explorer in residence and founder of Pristine Seas.

The coral looks like a huge, undulating brown rock from above. Some on the expedition even initially mistook it for a shipwreck.

Marine biologist and underwater cinematographer Manu San Félix dived down to look. “In the first second I realized that I was looking at something unique,” he said. It’s “close to the size of a cathedral.”

Up close, the coral morphs into something spectacular, with its complex network of polyps — tiny individual creatures that have grown over centuries to form this enormous coral — and splashes of vivid purples, yellows, blues and reds breaking up its brown hue.

The coral shelters a host of marine life including fish, crabs and shrimp. It’s also like a living encyclopedia, said San Féliz, containing information about ocean conditions going back hundreds of years.

Its sheer size caused some issues as the scientists’ measuring tapes were not long enough. They had to work in teams of two, stretching out the tape between them. When it ended, one person would stay in that spot while the other reeled up the tape, before swimming to them to continue the process.

The discovery is rare good news in an ocean of bad.

Corals are vital for the marine creatures that rely on them for food and shelter, but also for humans. They are an indirect food source for an estimated 1 billion people, by helping support fisheries, and provide a buffer against storms and sea level rise.

For the scientists, it’s a career highlight. “Making a discovery of this significance is the ultimate dream,” said Paul Rose, a National Geographic Pristine Seas expedition leader.

For the Solomon Islands, the mega coral could attract researchers, tourists and boost conservation funding, said Dennis Marita, the country’s director of culture at the Ministry of Culture and Tourism. “This is something huge for our community,” he said.

But, there is also “cause for alarm,” Pristine Sea’s founder Sala said. “Despite its remote location, this coral is not safe from global warming and other human threats.”

Corals are at risk from a range of local factors, including overfishing, which can damage and disrupt the delicate balance of their ecosystems, industrial pollution and sewage.

The biggest threat, however, is a global one: the fossil-fuel driven climate crisis.

Last month, scientists from the National Oceanic and Atmospheric Administration confirmed the global mass bleaching of coral reefs was the most extensive on record due to unprecedented ocean temperatures.

More than 40 per cent of warm-water reef-building coral species now face extinction, primarily because of climate change, according to the International Union for Conservation of Nature’s Red List of Threatened Species published Wednesday.

“The ongoing survival of corals… is in jeopardy,” said Derek Manzello, coordinator of NOAA’s Coral Reef Watch.

Yet while the mega coral remains vulnerable, he believes its health and longevity do provide a glimmer of hope. “The survival of this coral, which is hundreds of years old, illustrates that all is not lost for coral reefs,” Manzello told CNN. “This is a really cool finding to hear about!,” he added.

His sentiments were echoed by Emily Darling, director of coral reefs at the Wildlife Conservation Society, who called the discovery “a bright spot for coral reef survival.”

“This shows that there are still environmental conditions where corals can survive and thrive, even potentially through the accelerating impacts of climate change,” she told CNN.

Scientists have found evidence that the “Coral Triangle” — an area of tropical ocean that includes the Solomon Islands, as well as parts of countries like Indonesia and the Philippines — may be more resilient to coral bleaching, Darling added.

The discovery was announced as global leaders gather in Baku, Azerbaijan, for COP29, the UN-backed climate summit, where the focus this year is on mobilizing funding to help poorer countries tackle and adapt to climate change.

Finding this new coral, which is already at risk, is yet one more strong reminder of “the need for the rich counties to spend many more resources in reducing our carbon emissions,” Sala said.