Marty’s photo of the day #5001: This is a blue-chin parrotfish, and it grows to 30 inches in length. Like all parrotfish, it has two sets of teeth. The first set is fused into a beak that allows it to crush coral to feed on algae. The second set is in its throat, which grinds up the ingested coral to be excreted as sand. Yes, sandy tropical beaches are largely parrotfish poop.
(Photographed last month in the Galapagos Islands.)