There Are More Glow-In-The-Dark Fish Species Than We Originally Thought, Scientists Share
Bioluminescent creatures always fascinate humans, but considering that we don't actually know what's under most of the seas, would it come as a surprise that there are more glow-in-the-dark creatures than we thought?
— Harold Geller (@AstroBioProf) June 9, 2016
According to National Geographic, around 1,500 species of fish are actually bioluminescent - they can make their own light. These fish have lures coming out of their heads, glowing stripes on their bodies, goatees, flashing headlamps, or even bellies that can hide their silhouettes from predators.
Fish have evolved in numbers of ways - from generating light on their own, to forming partnerships with bacteria - nevertheless, these species from under the sea have abilities that not many land-dwelling creatures have.
Small, finned fish are not the only ones that evolved this way, either. Even sharks managed to have evolved and became bioluminescent at least twice in their known history.
"The fact that bioluminescence evolved so many times indicates that it serves some strong biological importance," lead author of the study, Matthew Davis, shared with the Smithsonian Magazine. "We also think that repeated evolution of bioluminescence was critical to species diversification [in] deep-sea and midwater environments."
However, for new species to evolve, these fish groups should be isolated enough from one another to develop their own traits. John Sparks, author of the study and curator-in-charge of the Department of Ichthyology from the American Museum of Natural History thinks that bioluminescence may be part of the reason for the diversity in the deep seas, as the number of species in a particular species' lineage seem to boom after their bioluminescent evolution - and again when it needs to adapt for a secondary use.
The Washington Post, for instance, pointed out that the lantern fish illuminates organs perfectly to blend with downwelling light, which makes sense as it was first to be thought to have evolved their organs for camouflage. It has since evolved again to let light migrate to form unique patterns on heads and sides instead.
Sparks shared, "Right now, we have no idea how they flash.And when something evolves so many times, you know it's obviously very important."