Coral-reef fish suck up meals with slime-covered lips

By Erin Ross

For hungry fish, corals make a difficult meal: venomous, coated with mucus and embedded in a razor-sharp, calcified skeleton. But one species, the tubelip wrass (Labropsis australis), has developed an unusual strategy to evade these stinging defences. The fish gives corals slime-covered kisses.

The finding, published on 5 June in Current Biology1, adds to scientists’ understanding of how corals and the fish that feed on them affect each other.

Wrasses that don’t feed on corals have thin lips and protruding teeth that resemble a beak. But tubelip wrasses have elongated, fleshy lips that they use to suck up a reef’s protective mucous coating. A scanning electron microscope reveals that the lips are furrowed with tiny channels and divots, soft and ribbed like gills on the underside of a mushroom. Those grooves contain mucous glands that can cover the wrasses’ lips in protective slime.

“We’ve never seen anything like this,” says David Bellwood, a marine biologist at James Cook University in Townsville, Australia, and a co-author of the paper. “Self-lubricating lips! Who would have predicted that?”

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