But in reefs with motorboat noise, the parents fan their eggs less and seem more agitated – swimming around more and possibly exposing their hatchlings to more predator attacks – than those hearing only minor motor noises or none at all.

“Any kind of unexpected noise can cause a rise in the stress response. And I think that’s what’s going on here with the parenting behaviour,” says Sophie Nedelec at the University of Exeter in the UK.