New study shines a light on the mechanics of bioluminescence in the rare fish Vinciguerria mabahiss

(Press-News.org) Los Angeles (February –, 2025)—Evolving roughly 27 different times in the long history of fish, bioluminescence—the biological production of light—is one of the flashier survival tools used for luring prey, communication, and recognizing potential mates among various species. In a new study published in Ichthyological Research, an international team of researchers studied the organs that produce light in Vinciguerria mabahiss, a rare species of fish from the Red Sea. This paper marks the first-ever close examination of these organs, providing key information on their structure and how V. mabahiss uses bioluminescence to make its way through the water—and laying the foundational groundwork for future scientists studying fish bioluminescence. 

“There are a lot of different ways that fish go about producing and using light,” says lead author Dr. Todd Clardy, Collections Manager of Ichthyology at the Natural History Museum of Los Angeles County.  “One of the things that we wanted to do was find out how this species of fish was using the light it produced. And part of that was by examining the structure of the photophore and not just how they looked at the cellular level, but we examined the size and the distribution of them across the body of the fish to try to assess what this fish was doing with these cool photophore organs, and it turns out they're using it as counter illumination.” 

While most of us might think of bioluminescence as an attractor—picture anglerfish luring prey with light in the depths—Clardy and his teammates found that V. mabahiss used its light to hide. Counter illumination is a kind of camouflage where an animal produces lights to make itself harder to be seen by predators. 

“We live in basically a two-dimensional world”, says Clardy. “I never think to look for a cheeseburger up above me. But fish are always looking up for a shadow passing over them because it’s either going to be food or a predator.” Counter illumination breaks up that shadow to mimic the light of the surface. “The fish is camouflaged, almost invisible.” 

Clardy and his team found that V. mabahiss have between 140 and 144 photophores of varying sizes throughout their bodies, all pointed downwards. Each photophore produces a blue light, breaking up the silhouette of the fish and camouflaging them from any predator looking up. They looked at five juvenile V. mabahiss specimens to better understand how the fish used its light. 

While the photophores varied in size, the researchers found that they all shared the same structure. The light is produced through a well-understood bacterial reaction, and the sophisticated composition of the photophores directs that bioluminescence into useful camouflage. “They have this thick pigment layer to block the light from entering the fish, reflective cells that amplify the light, and a lens that lets the light pass through,” says Clardy. 

A small fish only known to the Red Sea, V. mabahiss lives deep underwater and is seldom encountered by people, so much so that it has no common name. The findings from this study will provide bedrock information for future researchers to study bioluminescence in fish. “Its rarity means that V. mabahiss may be difficult to collect for most researchers,” says Clardy “We hope to provide information that other scientists can use for the broader study of bioluminescence.” 

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