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6 Scorpions that Glow in the Dark (How and Why)

While most people think they are insects, scorpions are actually arachnids and closely related to spiders and ticks. You may know they have venomous stingers, but did you know there are scorpions that glow in the dark? They glow a brilliant bluish or greenish color under ultraviolet (UV) light making them easy to find if you are trying to locate them or avoid them!

This article features 6 common species of scorpions that glow in the dark and provides answers to frequently asked questions on this fascinating ability they have. Let’s learn more!

6 scorpions that glow in the dark

Here is a list of 6 scorpions you can see glowing in the dark, especially if you go out looking for them with UV light.

1. Arizona hairy scorpion

Arizona hairy scorpion on rock
Arizona hairy scorpion on rock | image by gilaman via Flickr | CC BY 2.0

Scientific name: Hadrurus arizonensis

The Arizona hairy scorpion is the largest scorpion in the U.S. and also has a unique feature where their bodies are covered with small brown hairs. They grow between 5 and 7 inches long and are yellow with darker coloring on the top of their body.

These scorpions can be found in dry, hot places in Arizona, Utah, southern Nevada, Colorado deserts, and southern California.

2. Bark scorpion

Bark scorpion
Striped Bark Scorpion | image by Clinton & Charles Robertson via Flickr | CC BY 2.0

Scientific name: Centruroides exilicauda, formerly Centruroides sculpturatus

The most venomous scorpion in the U.S. is the bark scorpion that you can find in Arizona, southern California, Nevada, Utah, and southwestern New Mexico. These scorpions are light brown and grow up to 3 inches long.

Bark scorpions are excellent climbers and will often climb up walls to find ways to enter homes. Inside your home, you can sometimes see them walking across your ceiling.

3. Striped bark scorpion

Striped bark scorpion on black background
Striped bark scorpion on black background | image by USGS Bee Inventory and Monitoring Lab via Flickr

Scientific name: Centruroides vittatus

The striped bark scorpion is a small pale-yellow scorpion growing up to 2.75 inches long. Their venom is not dangerous to humans but causes sharp pain that can last 20 minutes.

Unlike bark scorpions, they prefer staying on the ground and don’t enjoy climbing. They spend most of their day under rocks and debris.

These scorpions are the most common species in the southwestern U.S. and can be found in Texas, Colorado, Arizona, New Mexico, Louisiana, and Tennessee. They are also the only scorpion species in Arkansas, Kansas, Illinois, Nebraska, Oklahoma, and Missouri.

4. Stripe-tailed scorpion

Stripe-tailed scorpion
Stripe-tailed scorpion | image by Andrew Meeds via Wikimedia Commons | CC BY 2.0

Scientific name: Paravaejovis spinigerus

Also known as the devil scorpion, the stripe-tailed scorpion gets its name from the dark brownish stripes on their light brown bodies. These scorpions grow up to 2.5 inches long and their venom is not considered dangerous to humans.

These common scorpions can be found in southern California, Arizona, New Mexico, and Texas. They can live in grasslands, mountains, sandy deserts, and other habitats.

5. Northern desert hairy scorpions

Northern desert hairy scorpion
Northern desert hairy scorpions | image by Matt Reinbold via Flickr | CC BY-SA 2.0

Scientific name: Hadrurus spadix

The northern desert hairy scorpion, also known as the black hairy scorpion, is a large scorpion with a black head and back. They grow around 5.5 inches long and uniquely have brown hairs covering their bodies.

You can find these scorpions in Colorado, California, Arizona, Nevada, Utah, New Mexico, Oregon, Washington, and Idaho. They are nervous and easily get aggressive. Although their sting is painful, their venom is less toxic and not life-threatening.

You may also like:  30 Examples of Ground Burrowing Insects

6. Black-clawed scorpion

Black-clawed scorpion on the ground
Black clawed scorpion on the ground | image by sheriff_woody_pct via iNaturalist | CC BY 4.0

Scientific name: Anuroctonus phaiodactylus

The black-clawed scorpion, also known as the mafia scorpion, are small, light yellow to dark brown scorpions, growing under 2.5 inches long. They also have dark coloring and black at the tip of their pinchers.

While most scorpions are in the southwestern states, you can find these scorpions in Oregon, Washington, Idaho, Nevada, California, and Utah. They prefer dry desert-like habitats and have pretty mild venom, not dangerous to humans.

More about why scorpions glow in the dark

How do scorpions glow in the dark?

The exoskeleton of scorpions consists of an outermost layer called the hyaline layer. This layer is tough, thin, and contains a fluorescent chemical that glows under UV light, such as black light or natural moonlight.

The glow of scorpions isn’t a sign of radioactivity. Instead, scientists have said it’s a chemical reaction to the chemicals that exist naturally in scorpions.

Why do scorpions glow in the dark?

Scientists aren’t entirely sure why scorpions glow in the dark, however, there are multiple theories. Some of the common reasons are that the glow:

  • Protects them from sunlight
  • Helps them locate each other
  • Confuses their prey when they hunt

One well-researched theory is that the glow helps scorpions know when it is safe to come out at night. Scorpions have bad eye-sight but can see the colors blue-green the best.

By converting the moon’s UV light into a greenish-blue glow on their body they can see how much they glow and determine if there is too much moonlight. Too much light means predators can easily see them and it’s safer for them to stay underground or hidden. This also explains why these nocturnal animals are less active during full moon nights.

Do scorpions glow in the dark all the time?

Typically scorpions glow all the time, except right after they molt. Molting is a process where the scorpion’s skin cracks and opens up. The scorpion sheds their skin to grow a new exoskeleton.

Scientists have found that the chemicals in the hyaline layer that make them glow are only present once their exoskeleton has hardened. This can take a few days after molting.

Another interesting fact is this hyaline is so durable that scorpion fossils can still glow under UV light after millions of years. Scorpions preserved in alcohol can also cause the liquid to glow under UV light!

Check out these interesting facts about scorpions!