In the finale Jurassic World—and spoiler warning for anyone who hasn’t seen it—Bryce Dallas Howard’s character uses a flare to summon a Tyrannosaurus, which then battles the film’s main antagonist Indominus rex. As the two predators duke it out, the humans escape.

A similar strategy plays out in the Great Barrier Reef. When threatened by predators, the lemon damselfish sheds a chemical alarm—a substance housed in its skin that says, “I’m being attacked!” This message isn’t intended for other damselfish. It’s not a warning or a call for help. Instead, it attracts even more predators.

One idea is that the chemicals are not alarms but disinfectants, which help to keep wounds free from infections if the victims should escape. But