The Animal That Glows Red Under UV Light – Secret Colors of the Wild

To the human eye, the world seems full of colors — from the deep blue of the ocean to the vibrant green of rainforests. But we’re actually missing out on a whole spectrum of light we can’t see.

Ultraviolet (UV) light, invisible to us, reveals a hidden world of glowing patterns and strange signals — especially in animals.

And one of the most surprising discoveries in recent years? Some animals glow bright red under UV light, even though they look completely normal in daylight.

Biofluorescence vs Bioluminescence

Before we dive into the red-glowing mystery, let’s clear up one common confusion.

• Bioluminescence: This is when an animal creates its own light, like fireflies or deep-sea anglerfish.

• Biofluorescence: This is when an animal absorbs light and re-emits it as a different color — often only visible under UV or blue light.

So, when an animal glows red under UV, it doesn’t mean it’s shining in the dark — it’s reacting to invisible UV light and revealing a secret color.

The Glowing Gecko Surprise

In 2018, scientists studying Tokay geckos (a species native to Southeast Asia) made a wild discovery.

When exposed to UV light, these lizards — normally greyish-blue with orange spots — glowed in a bright fluorescent red and green pattern!

Why? Their bones, skin, and especially their heads and tails had compounds that responded to UV light.

And this isn’t just a Tokay thing — several species of geckos and even frogs show similar patterns.

Frogs, Sharks, and Squirrels?

Yes, frogs too. Some tree frogs, when placed under UV light, shine with bright red or blue fluorescent patches.

Even weirder? Flying squirrels — mammals! — were found to glow bubblegum pink under UV.

And certain sharks, like the chain catshark, have skin that glows green under UV light.

Nature clearly has a hidden glow-up going on, and we’re only just discovering it.

But Why Do They Glow?

Good question. Scientists are still figuring it out, but here are a few theories:

1. Communication: Some animals, like geckos, are active at night. Since many reptiles and amphibians can see UV light, glowing under UV might help them recognize mates or rivals.

2. Camouflage or Signaling: In dense forests or underwater environments, biofluorescence could help blend in or stand out, depending on the surroundings.

3. UV Protection: Some compounds that cause fluorescence may also act like natural sunscreen, protecting animals from UV rays.

4. Totally Accidental: Some scientists believe it might just be a by-product of certain proteins or chemicals in the animal’s skin — not necessarily useful.

How Is It Studied?

To study UV fluorescence, scientists use UV lamps and special cameras that can detect short wavelengths of light.

Many of these discoveries happened by accident — like someone shining a UV flashlight at a frog in the jungle, or noticing a weird glow on an animal in a museum specimen room.

There could be hundreds more glowing species we haven’t even noticed yet.

Who Can See UV Light?

Humans can’t — at least not without equipment. But many animals can see UV naturally, including:

• Bees

• Birds

• Reptiles

• Amphibians

• Some fish

So even if we don’t see the glow, they might be flashing secret signals to each other all the time — invisible to us.

Imagine living in a world where you walk past someone and their skin glows red or green, but only if you have UV vision.

Final Thought

We often think we understand the world around us just because we can see it. But animals glowing under UV light remind us that there's always more than meets the eye.

From lizards to squirrels, frogs to fish, the natural world is hiding a vibrant, glowing language — one we’re only beginning to decode.

So next time you see a gecko on the wall or a frog by a stream, remember: under the right light, they might be secretly glowing like neon signs in the night.