And the parrotfish isn’t alone here. “In places like Hawaii, where we have very little terrestrial input of sand, almost all of our sand is of biological origin,” Ong said. “So I like to tell people that the sand you’re standing on in Hawaii has probably gone through the gut of something. It’ll have gone through the gut of a parrotfish, a sea urchin, some kind of worm.”
Now, if you’re anything like me, you considered eating chalk at some point in your childhood. Luckily I never did—which isn’t to say I didn’t come close—because blackboard chalk used to be made of calcium carbonate, exactly what coral is made of. And when calcium carbonate mixes with acid, it fizzes like crazy. “It creates carbon dioxide,” said Ong. “So if you’re a regular animal and you had acid in your stomach and you ate a chunk of chalk, you would get fizzy quickly. It would be generating a lot of gas.”
Mucus Sleeping Bags and Polychromatic Sex Changes All of this beach-building is exhausting work, and indeed the parrotfish is a strangely heavy sleeper. Like, dangerously heavy. “They don’t wake up easily at all, which makes them fairly easy to catch,” said Ong, “because you can go down and shine a light at them and they’ll be sound asleep. And the ones you do catch, you put them in a dark bag and they go back to sleep.”
Ong isn’t sure why exactly they need such deep sleep, though it wouldn’t seem to make much evolutionary sense. Why leave yourself so vulnerable?
Well, younger, smaller parrotfish, which are of course more susceptible to predation, have a brilliant little trick. They tuck themselves into a crevice or under a ledge and secrete mucus to build a translucent, semi-solid sleeping bag, which balloons to encase the parrotfish in a water-filled bubble. It’s likely a measure to mask their scent from predators, or a kind of proximity sensor to detect when something is closing in. And when they wake up in the morning, they’ll recycle the cocoon by eating it for breakfast. Try doing that with your sleeping bag the next time you go camping.
You see, most parrotfish species are sex-changers. Individuals are born female and form into schools. Once they’ve matured, the largest female will change into a male, assuming rule over the school, which essentially becomes his harem. He begins managing territory, chasing away rival males, and transforms his drab skin into the gaudy colors in the photos above.
Yet this color shift doesn’t happen every time. Some males eschew the lovely new outfit in favor of a more sneaky strategy: They pretend to still be female. “So when it comes to spawning, they can sneak in,” said Ong. “When the males and females spawn—either in the territory, or some of them actually congregate in a place and they group-spawn—the sneaker males can insert themselves in there. And there are a fair number, so it’s a reproductive strategy that must work.” (The giant Australian cuttlefish actually does the same, with males manipulating their arms to look like females, sneaking under dominant males to steal a kiss with their mates, and by steal a kiss I mean hand her bundles of sperm.)
Indeed, the creatures are overfished in most parts of the world, setting off a domino effect that leaves coral, already struggling to survive climate change, at the mercy of algae. And interestingly, according to Ong, parrotfish seem to be getting smaller. Could we be artificially selecting against the largest individuals by removing them from the gene pool? After all, we seem to have done the same with elephant tusks, poaching individuals with the most ivory and keeping them from passing along their genes for such size.
Really, it’s no way to treat such a wonderfully bizarre fish, much less a creature that’s building our beaches free of charge. So the next time you’re lounging in the sands of Hawaii, take a moment to appreciate the parrotfish, which only ever wanted to gnaw on coral and sleep in its own snot, and maybe, if it’s lucky, undergo a sex change. And if that’s not one hell of an iconoclastic life, I don’t know what is.
source: wired.com By Matt Simon