World’s Largest Sea Creature

Take a moment to imagine what you think is the largest sea creature on Earth. How big is it? Are you thinking of the blue whale? At somewhere between 80 to 110 feet long, blue whales are about as long as an NBA basketball court, and, at 20 to 25 feet across, about half as wide as one.

But go bigger. Imagine a creature the size of two basketball courts, side by side, as tall as nearly two basketball hoops, and visible from space. It’s not a whale—it’s a single coral colony that scientists and filmmakers recently discovered in the Solomon Islands, an archipelago of more than 1,000 islands located about 1,100 miles northeast of Australia. At 105 by 111.5 feet, it’s the largest recorded sea organism to date, though larger undiscovered ones likely exist, given that about 5 percent of the oceans have been explored.

Many people may not realize that coral is an animal since it’s small and anchored in place. Corals live in colonies of hundreds of thousands of individual animals, called polyps. The polyps of hard corals secrete calcium carbonate that cements them together and protects them. Each polyp is a tiny, stout column with tiny tentacles that catch food and usher it into the mouth. But coral polyps also have a symbiotic relationship with microscopic algae. These algae live inside the coral and their photosynthesis provides the coral with nutrition in exchange for protection from animals that would eat the algae.  

The massive coral colony in the Solomon Islands is a brown hard coral called Pavona clavus. It’s a bumpy mound covered in knobs, situated more than 30 feet deep and teeming with hundreds of other species. It’s estimated to be a hearty 300 to 500 years old. And although more than 40 percent of the world’s coral species are at risk of extinction, this coral appears healthy and resilient.