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Deep-sea shrimp have evolved enhanced vision for the bioluminescent world, study finds

Light is a primary driver of visual evolution in shrimp, according to new FIU research this week in Nature Communications.

The deep sea is a dark place, with the only light coming from animals that glow (bioluminescence) and occasional faint glimmers from the surface above. Led by biologist Danielle DeLeo, this new FIU research reveals animals that live in the deep sea use this light to navigate the ocean and potentially discriminate different sources of bioluminescence. This study specifically looked at a group of deep-sea shrimp called Oplophoroidea that can migrate vast distances, up and down in the water column.

Some of these shrimp have special glowing organs that they use to camouflage, defend themselves and maybe even communicate. The scientists say these shrimp have evolved visual systems with a diversity of special light-detecting proteins that can help them navigate their bioluminescent world.

"As primitive eyes evolved in the oceans during the Cambrian explosion some 540 million years ago—a time when we now know bioluminescence already existed—understanding how different light sources impact vison in present-day species can illuminate their past influence on early animals," said DeLeo, who conducted the research while a postdoctoral researcher at FIU. She is currently a postdoctoral fellow at Smithsonian's National Museum of Natural History.

The proteins, called opsins, allow the shrimp to see a range of colors including environmental and bioluminescent blue light. They might possibly be able to differentiate between their own glow and the bioluminescence of others. The study found that shrimp that migrate into shallower waters, where there is more available light, have a greater variety of these light-detecting proteins.

This is likely because they need to see a wider range of colors to navigate and survive in their more complex light environment, according to Heather Bracken-Grissom, FIU biologist and assistant director of the Coastlines and Oceans Division in the Institute of Environment.

"We are just beginning to understand how visual systems have evolved in light-limited environments and how animals may be using bioluminescent signals to communicate with one another," Bracken-Grissom said. "There is still a lot to learn, but this study can pave the way for future research in other deep-sea groups."

This research helps improve the understanding of how deep-sea animals are able to not only live but thrive in such extreme and dark conditions. This study suggests that navigating across different light environments in the deep sea is important, especially for those that migrate into more shallow waters. These opsin proteins may also be particularly important in helping these shrimp in recognizing which animals are friends and others that might be foes.