White Sandy Beaches and Parrotfish Poop

Mathematicians at the University of Hawaiʻi estimate the Earth holds a total of seven quintillion, five hundred quadrillion grains of sand. How they came up with that number is a mystery to most, but where those grains of sand come from is a bit easier to understand. Poop.

That’s right. Hawaiʻi’s beautiful, white sandy beaches contain a significant amount of fish poop. Parrotfish poop to be exact. Parrotfish are responsible for creating up to 85 percent of sand produced on reefs. Also known by their Hawaiian name, uhu, parrotfish don’t have stomachs. After munching on a delicious meal of dead coral, that same coral is broken down into sand before traveling through the long intestine and shooting out the exit door in blast of sand.

Although other marine life like oysters and sponges also produce sand, the parrotfish is the boss of sand production, producing thousands of tons of sand annually. In fact, one large parrotfish can produce over 800 pounds of sand per year! The Maui Ocean Center claims the native Hawaiian name for the female red lip parrotfish translates into “loose bowels.”

Important in regulating the health of the reefs, the colorful parrotfish is remarkably unique in other ways as well. Parrotfish are what scientists call ‘protogynous hermaphrodites,’ meaning they have the ability to change from female to male. This sexual fluidity also allows them to change their color patterns, which range from relatively bland to brilliantly colorful.

Another unique characteristic of the parrotfish is their practice of wrapping themselves in a transparent cocoon created from mucous that is secreted from an organ located on their head. Researchers believe these fish ‘pajamas’ mask the fishes’ scent, making it more difficult for their natural predators to find them.

With about 80 species ranging in size from one to four feet, parrotfish are plentiful among the world’s tropical reefs. The fish are considered a royal delicacy in some parts of the world like Polynesia where it is eaten raw, yet in the United States it is rarely consumed.

So the next time you’re snorkeling near a coral reef, keep your eyes and ears peeled for these beautiful, colorful creatures. If you listen carefully, you can hear them munching on the reef’s coral skeleton. The parrotfish are vital for coral reef ecosystems, especially today as our beaches are threatened by rising seas. If it weren’t for these pooping, sand-making machines, a significant amount of the world’s island-building sediment would disappear.

So the next time you spread your blanket out on a beautiful white sandy beach on the Island of Hawaiʻi, give thanks to the generous digestive system of these lovely creatures. Praise the poo!