As reported by Richard Kemeny in Science, If you’re a fish with an itch, a shark would seemingly be the last thing you’d turn to for a scratch. Yet scientists now report spotting several species of fish swimming up to sharks and intentionally rubbing them. The prey appear to be using the predators’ rough skin to rid themselves of parasites.
For their part, the sharks don’t seem entirely thrilled by the attention. In 38% of the study’s observations, they tried to dodge the itchy fish by turning abruptly, swimming up and down, or diving in a corkscrew fashion. What’s unclear is whether the sharks were trying to avoid the irksome chafing itself—or the fishes’ parasites.