Team of biologists discover fluorescence in 27 marine creatures

A team of zoologists and marine biologists affiliated with several institutions in Indonesia, working with a colleague from Germany, has discovered previously unknown instances of fluorescence in 27 marine creatures.

In their paper published in the open-access journal PLOS ONE, the group describes their search for fluorescence in marine creatures over the course of three years in both the Red Sea and the Banda Sea.

Prior research has shown that some marine creatures have bioluminescence, which is the ability to produce light. Other creatures have something else, called fluorescence, where all or parts of them shine brighter than normal when certain types of light are focused on them.

In this new study, the research team used a "Sola" light source, which is used for illuminating targets of microscopy, to find fluorescence in sea creatures.

Fluorescence can be observed when certain molecules absorb certain wavelengths of light and then re-emit that light at longer wavelengths. Marine creatures with fluorescence gain a reproductive advantage because it allows them to absorb the limited amount of light that is available to them underwater and emit light that is more visible at deeper depths, making it possible for others to see them.

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In their quest to find more sea creatures that have fluorescence, the research team conducted periodic dives in the Red Sea, off the coast of Egypt, and the Banda Sea, off the coast of the Banda Islands, Indonesia—from early 2019 to late 2022. All the dives were conducted at night, and were never deeper than 15 meters and the team used Leica THUNDER microscopy cameras to collect their images.

The efforts by the research team paid off, as they were able to find fluorescence in 27 species of marine creatures that had never been documented before. The types of species were widely varied, from fish to sponges and octopus. They also found fluorescence on different parts of the bodies of the creatures, and sometimes more than one type of fluorescence on the same creature.

Among the instances of newly found fluorescence were species of boxer crabs, snake pipefish, and multiple species of stony corals. The team also noted that some were truly unique, such as the scarlet frogfish, which fluoresced green all over its body but also displayed random orange patches.