Although coral reefs are home to bustling communities of gaudy marine life, half the fishes that live there are hardly ever seen. Aptly known as cryptobenthics—literally “hidden bottom-dwellers”—these species are mostly shorter than two inches and usually hidden in crevices. If you snorkel past, they’ll scurry away. But Simon Brandl of Simon Fraser University has made a career of studying them. And he and his team have now shown that cryptobenthics are a crucial component of healthy reefs because they, more so than other fish, are extremely good at dying.
Pretty much every predator on the reef eats cryptobenthics, and a full 70 percent of these tiny morsels are devoured every week. But since they also reproduce, hatch, and grow at equally phenomenal rates, new individuals are constantly replenishing the ones that are consumed. Entire generations can turn over in a matter of weeks. And this extreme life cycle, Brandl found, is the secret engine of the world’s coral reefs, fueling the food webs that allow their inhabitants to flourish in otherwise nutrient-poor waters.
Large, colorful fish such as groupers, wrasses, and parrotfish “are what people focus on because they’re the ones you see when you’re diving,” says Julia Baum, a coral researcher at the University of Victoria. “But I love it when a study like this comes out of the blue and says that maybe these tiny fish might be the ones that are fueling everything else on the reef. That’s very cool.” [Continue reading…]