These Fish Have Headlights

The flashlight fish, or Anomalops katoptron, has bioluminescent patches below its eyes to help see food deep underwater. In other words: headlights!

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Screenshot: YouTube / National Geographic

The deep sea is nature’s engineering department. The creatures that live in the briny deep have adapted some amazing ways of surviving and thriving in their extreme habitat. Like this species: Anomalops katoptron, better known as the flashlight fish, so named for its bioluminescent patches. If you ask me, these are headlights.

I first learned about the flashlight fish on Twitter via a video showing a small group of these little guys in an aquarium in a dark room. In this context, with a little bit of background lighting, their teal blue headlights are super prominent. Check it out:


In their natural habitat, you’re far less likely to see the flashlight fish so clearly. They hang out along coral reefs, using their little headlights to help them see to find food and swim in schools.

Those bioluminescent patches are a fascinating instance of symbiosis, too: The glow comes from luminescent bacteria that grow in those patches that I’m steadfastly referring to as headlights. The flashlight fish evolved to send extra oxygen to the patches where the luminescent bacteria grow, allowing the bacteria to thrive and create useful light for the fish.

The fish can even turn their little headlights on and off, depending on whether they need illumination to see around them or darkness to hide from a predator.

Scientists are still learning about the flashlight fish and how they use bioluminescence to their advantage. Here’s a fun video from National Geographic — you can hear the excitement in the voice of marine biologist David Gruber as he explains how he and his film crew happened upon this school of flashlight fish.

Tiny Fish Use Bacteria to Glow in the Dark | National Geographic

Now we just have to figure out how to give these little guys some taillights — maybe some universal-fit trailer lights to start?