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Oceans and Sea Life · entry 33 of 52
Parrotfish graze on coral and produce fine white sand as a by-product of their feeding.
The longer version
Beaks scrape reef surfaces clean, taking algae and coral tissue along with the rock they grow in. Powerful jaw muscles drive that bite, and grinding plates further back pulverise gritty material before it passes through the gut.
Sand is simply what survives the journey undigested, settling near the reef and eventually washing onto tropical beaches. Grazing also clears space so coral larvae can settle and keeps faster-growing seaweed from smothering everything. Concentration of grazers matters: too few, and algae take over. Too many, and the reef itself wears down faster than it can rebuild. Their feeding is audible underwater as a steady crunching near the reef.
Where this entry sits
Oceans and Sea Life looks at the salt water that covers most of the planet, from crashing waves and tides to the darkest deep-sea trenches. Expect notes on coral, fish, whales, sharks, jellyfish, shells, and the strange creatures that live far below the surface. The full list sits on the Oceans and Sea Life page, where every entry is listed in order.
More From Oceans and Sea Life
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Read 36Orcas hunt in coordinated groups and pass hunting techniques down through family lines.
Read 37Baleen whales filter seawater through bristly plates, trapping krill and small fish inside their mouths.
Read 38Krill swarm in vast numbers in cold polar seas and feed many larger animals.
Read 39Penguins are flightless birds that use their wings to swim rather than to fly.
Read 40Albatrosses glide for hours over the ocean, using wind rising off the waves to stay aloft.
Read 41Turtles return to the beaches where they hatched to lay their own eggs years later.
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