Over three million sea cucumbers excrete 64,000 metric tons of nutritious poop back into their ecosystem in one reef.
Holothuroidea, commonly known as sea cucumbers, belongs to the echinoderms' family; these are strange cylindrical marine invertebrates closely related to starfish and sea urchins.
These bizarre creatures have no eyes and use their anus for both defecating and breathing. They spend most of their lives scooting on the seafloor, scouring sediments for food, and excreting it back into the ecosystem.
According to a new study published in Coral Reefs, with roughly 1,250 unique sea cucumber species in the ocean, all of that excess excrements seem to play a significant role in the coral reef ecosystems' health.
Are Sea Cucumbers Important?
Using satellite imaging and drones, researchers from the University of Newcastle, Macquarie University, and James Cook University found that sea cucumbers can generate over 64,000 metric tons of fecal waste annually across one coral reef, according to the University of Newcastle, Australia's press release.
Like earthworms, holothurians aerate ocean sediments by sucking them up and consuming micro-organisms, and then spitting back the dirt out. Researchers say that sea cucumbers release other beneficial derivatives such as calcium carbonate, ammonia, and nitrogen during this process.
Using drone footage, researchers analyzed sea cucumbers at the southern end of the Great Barrier Reef, where they found a total of 3 million sea cucumbers living within the shallow areas of the reefs.
Vincent Raoult, co-author and reef ecologists at the University of Newcastle, ran feeding experiments on the most abundantly found cucumber on the reef, Holothuria atra, or the black sea cucumber. The goal of the experiments was to see how sea cucumbers excreted much fecal matter in a day.
Findings show that a sea cucumber defecates 1.3 ounces of poop daily. 30.8 pounds of feces annually or the equivalents of 5 Eiffel towers in weight. Although the amount of excrements the marine invertebrate defecate seems like many studies show, it is vital in maintaining a healthy coral reef.
Threats to Sea Cucumbers
Despite the critical role of sea cucumbers in reef ecosystems, the warty worms face extinction threats from overfishing. Sea cucumbers are considered a delicacy in many cultures and are valued at an estimated $80 per kilo.
Researchers hope that the findings published can expand the global sea cucumber population's count and management while promoting conservation efforts.
Co-author Jane Williamson says in a statement, "It's tough though for scientists to have a sense of what the loss of a species might be if we don't know the scale of their role in the ecosystem."
She adds, "we're advocating that the functional role of sea cucumbers on coral reefs is likely to be much more substantial than previously thought, and therefore greater attention needs to be directed to their management and ecology. Particularly when it comes to overharvesting of reefs that are already compromised."
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