Study traces bioluminescence back 540 million years in octocorals

Published in the Proceedings of the Royal Society B on April 23, the study provides new insights into when and why organisms started to light up. Historically, the earliest record of bioluminescence in animals was dated to approximately 267 million years ago in ostracods. The new findings suggest a far earlier emergence in octocorals, highlighting their ancient lineage and frequent luminous capabilities.

"Nobody quite knows why it first evolved in animals," stated Andrea Quattrini, the museum's curator of corals and senior author of the study.

The research, led by Danielle DeLeo, a museum research associate, utilized a comprehensive evolutionary tree of octocorals developed in 2022. This tree, based on genetic data from 185 octocoral species, helped pinpoint the division points of their lineage. Integrating the ages of octocoral fossils with this phylogenetic tree, the team mapped bioluminescent species and employed statistical analyses to infer the traits of ancestors.

"Our statistical methods suggest that 540 million years ago, the common ancestor of all octocorals was likely bioluminescent," explained Quattrini. This predates the previous records by 273 million years, indicating that bioluminescence has been a significant trait in the evolutionary history of octocorals.

The persistence of this trait among octocorals, which includes soft corals, sea fans, and sea pens, suggests it has been crucial for their survival and evolutionary success. Although the exact functions of bioluminescence in octocorals remain unclear, its long-standing presence points to its importance in their ecological interactions.

Further research aims to explore the genetic basis of bioluminescence in octocorals and its ecological implications, particularly how environmental factors might influence the expression of this trait.

The findings not only shed light on the ancient origins of bioluminescence but also offer critical insights into the conservation and management of octocoral species, which face threats from climate change and human activities.

Research Report:Evolution of bioluminescence in Anthozoa with emphasis on Octocorallia