The origin of marine bioluminescence dates back to the dawn of complex life

The seabed is full of still unknown wonders, and the recent discoveries of an international team of researchers are proof of this. Their work reveals the existence of eight marine organisms with previously unknown luminosity, dating back to the Cambrian era, around 540 million years ago.

Luminous corals in the ocean depths

Led by Danielle DeLeo of the Smithsonian Institution, researchers identified eight organisms exhibiting previously unknown bioluminescence. While corals in shallow waters are rarely bioluminescent, those in the deep ocean can display vibrant colors and captivating shows. The purpose of these fascinating light displays has long intrigued scientists, who speculate that they could be used to attract large predators to scare away small marine organisms that feed on corals, or even to attract prey.

The genetic research was based on the findings of Manabu Bessho-Uehara, a researcher at Nagoya University, and Andrea Quattrini, of the Smithsonian Institution. In a previous study, Bessho-Uehara identified several new bioluminescent corals in the deep sea, leading him to suspect the existence of many other as-yet-unidentified specimens.

New bioluminescent species discovered

Bessho-Uehara and Quattrini conducted field work from shallow waters to the abyss, including at Nagoya University’s Sugashima Marine Station near the city of Toba in central Japan, to find more specimens bioluminescent. They thus discovered previously unknown bioluminescence in two types of Hexacorallia (soft corals) and five types of Octocorallia.

I was excited, because we were the first to discover bioluminescence at the genus level in five genera: the corals Bullagumminzoanthus, Keratosidinae, and Corallizoanthus, as well as the sea feathers Echinoptilum and the deep sea fans Metallogorgia“, Bessho-Uehara said of this discovery.

Going back to the origins of bioluminescence

Using the team’s findings on modern organisms, a multidisciplinary team including the Smithsonian National Museum of Natural History, Florida International University, Monterey Bay Aquarium Research Institute, University of California and Harvey Mudd College, used genetic information from these organisms to construct a phylogenetic tree to trace the origins of bioluminescence in anthozoa, the class of marine organisms that includes corals and similar organisms.

The researchers’ results suggest that bioluminescence first appeared in a common ancestor of Octocorallia corals. Combining this data with the fossil record, the team discovered that this ancient coral existed during the Cambrian period, around 540 million years ago, making it the oldest bioluminescent organism known to date. .

New insights into Cambrian ecology

These findings also provide insight into the evolution of organisms, which primarily took place in the oceans during the Cambrian era. At this time, invertebrates developed eyes with sensitive photoreceptors in the light. This suggests the exciting possibility of light-mediated interactions between anthozoans and organisms with photoreceptors, thereby shedding new light on the ecology of a crucial period in the evolution of life.

When he saw the results, Bessho-Uehara’s first thought was that “the ocean is full of wonders“. He added: “I remember being so amazed when we discovered that bioluminescence had appeared twice as early as previously thought.”

Illustration caption: Laboratory photo of the bioluminescence of the sea fern Funiculina sp. observed under red light. (credit: Manabu Bessho-Uehara © 2020 MBARI)

The study, “Evolution of bioluminescence in Anthozoa with emphasis on Octocorallia,” was published in Proceedings of the Royal Society B April 24, 2024 – DOI: 10.1098/rspb.2023.2626.

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