Evolution of bioluminescence in Anthozoa with emphasis on Octocorallia

Bioluminescence is a widespread phenomenon that has evolved multiple times
across the tree of life, converging among diverse fauna and habitat types.
The ubiquity of bioluminescence, particularly in marine environments where
it is commonly used for communication and defense, highlights the adaptive
value of this trait, though the evolutionary origins and timing of
emergence remain elusive for a majority of luminous organisms. Anthozoan
cnidarians are a diverse group of animals with numerous bioluminescent
species found throughout the world’s oceans, from shallow waters to the
light-limited deep sea where bioluminescence is particularly prominent.
This study documents the presence of bioluminescent Anthozoa across depth
and explores the diversity and evolutionary origins of bioluminescence
among the Octocorallia – a major anthozoan group of marine luminous
organisms. Using a phylogenomic approach and ancestral state
reconstruction, we provide evidence for a single origin of bioluminescence
in Octocorallia and infer the age of occurrence to around the Cambrian
era, approximately 540 million years ago- setting a new record for the
earliest timing of emergence of bioluminescence in the marine environment.
Our results further suggest this trait was largely maintained in
descendants of a deep-water ancestor and bioluminescent capabilities may
have facilitated anthozoan diversification in the deep sea.