Sea Cucumbers on One Coral Reef Drop Several Eiffel Towers’ Worth of Poop Each Year—and That’s a Good Thing

To be clear, this is the sea cucumber.
To be clear, this is the sea cucumber. / PeachLoveU/iStock via Getty Images

You might give back to your community by donating old clothes or volunteering at a food bank. Sea cucumbers offer something a little less conventional: poop, and lots of it.

According to a recent study published in the journal Coral Reefs, the black sea cucumbers (Holothuria atra) along one segment of the Great Barrier Reef produce more than 64,000 metric tons of excrement each year—or about the mass of five Eiffel Towers. Though arriving at that estimate didn’t entail physically measuring every metric ton, researchers did spend a memorable 24 hours “spooning poo,” as reef ecologist and study co-author Vincent Raoult told The Guardian.

The researchers used drones and satellites to estimate that more than 3 million black sea cucumbers live on the outer and inner coral reefs bordering Heron Island off Queensland, Australia. In order to approximate how much feces that population generates annually, they first had to determine how much one sea cucumber poops in a single day. So the team monitored individual specimens in tanks. “Every hour we would sit there, and take a spoon, and collect the little fecal pellets these sea cucumbers would produce,” Raoult explained. They found that each sea cucumber is responsible for around 38 grams of poop per day, which they extrapolated to arrive at roughly 64,000 metric tons across the whole reef per year.

Some of Heron Island's corals.
Some of Heron Island's corals. / Nigel Marsh/iStock via Getty Images

More research is needed before we draw any conclusions about how this affects the health of the reef and its other inhabitants, but it’s likely a good thing. Sea cucumber defecation is a method of bioturbation, meaning it helps stir up sediments on the ocean floor. This can release nutrients vital to the ecosystem—like calcium carbonate, which makes up coral skeletons and other organisms’ shells. As oceans absorb the carbon dioxide released when we burn fossil fuels, the water becomes more acidic, and calcium carbonate structures deteriorate more rapidly. In other words, sea cucumber poop could be freeing up additional calcium carbonate, which helps coral reefs resist the effects of climate change.

Again, more research is needed, but it’s possible we should be celebrating the excretory achievements of Heron Island’s sea cucumbers much like we do with newly potty-trained toddlers.

[h/t The Guardian]