Animals that follow the Moon

The evidence

On the Great Barrier Reef, 32 coral species spawn together a few nights after a spring full moon, cued by moonlight and the dark gap before moonrise. The worm Platynereis keeps a monthly clock set by night light. Dung beetles steer by the Moon’s polarised light.

Key studies

• Mass Spawning in Tropical Reef Corals Harrison P. L. et al.·Science·1984 32 coral species spawned together a few nights after the late-spring full moon.
• Signaling cascades and the importance of moonlight in coral broadcast mass spawning Kaniewska P. et al.·eLife·2015 Moonlight is one of the cues that set the timing of spawning.
• Moonrise timing is key for synchronized spawning in coral Dipsastraea speciosa Lin C.-H. et al.·Proceedings of the National Academy of Sciences·2021 The dark gap between sunset and moonrise, after full moon, triggers spawning.
• Circadian and Circalunar Clock Interactions in a Marine Annelid Zantke J. et al.·Cell Reports·2013 A monthly clock in its brain, set by night light, runs alongside its daily clock.
• Insect orientation to polarized moonlight Dacke M. et al.·Nature·2003 The first animal shown to steer by the polarised light of the Moon.