Bioluminescence, a captivating phenomenon where living organisms emit light through chemical reactions, has a deep-rooted history on Earth. This study reveals that bioluminescence emerged over 500 million years ago, with its earliest known evolutionary roots traced back to the depths of the ocean during the Cambrian period. This discovery challenges previous beliefs, as it surpasses the age of the previously oldest known bioluminescent creature, a tiny deep-ocean crustacean that lived 267 million years ago.
The study, published in the Proceedings of the Royal Society B Biological Sciences, focuses on octocorals, a class of corals with eightfold symmetry and softer skeletons. These creatures are fascinating, as they emit bioluminescence when disturbed, possibly to lure prey or attract predators to feed on smaller fish that damage the coral. The research team, led by marine biologist Danielle DeLeo, utilized genetic data from 185 octocoral taxa to construct a detailed family tree, identifying and tracing the lineages of known bioluminescent octocoral species.
Through statistical analyses, the team concluded that bioluminescence first emerged in the common ancestor of all octocorals around 540 million years ago. This finding coincides with the presence of marine invertebrates with light-sensitive eyes in the Cambrian ocean, suggesting potential interspecies interactions that may have driven the evolution of bioluminescence. However, the study also raises intriguing questions about why only a few octocoral species retain bioluminescence today and how they lost this ability over time.
The research highlights the importance of understanding the ancient ecology of the Cambrian ocean and invites further exploration into the evolutionary history of bioluminescence. For those interested in learning more, ScienceAlert offers a free Spark newsletter with a chance to win a $10,000 vacation, including a bioluminescent night kayaking tour, until December 11, 2025.
