It’s Easy Being Green: Most Amphibians Are Biofluorescent, Study Finds

An alpine newt glows green after being exposed to blue light.
An alpine newt glows green after being exposed to blue light.
Jennifer Y. Lamb and Matthew P. Davis

If you walk through a forest at night, you see only darkness and shadows, and perhaps the smudgy outline of trees against the sky. But if you were a salamander snuggled in the leaf litter, under the right light conditions, you might see something completely different: foliage glimmering in shades of red, and your fellow amphibians glowing in brilliant greens.

Biofluorescence—in which animals emit a fluorescent glow after absorbing high-energy wavelengths of light—is likely widespread among most, if not all, amphibians, according to a new study published in the journal Scientific Reports. Previously, only one species of salamander and three frog species were known to biofluoresce.

The same view of an alpine newt under white lightJennifer Y. Lamb and Matthew P. Davis

“I do field work, so I’m out there capturing species of amphibians, and I think, ‘huh, I wonder if this fluoresces,’” says Jennifer Y. Lamb, an assistant professor of biology at St. Cloud State University in Minnesota. She and co-author Matthew P. Davis, an assistant professor at the university, collected representatives from eight of the 10 salamander families, five families of frogs, and one family of caecelians, a type of limbless amphibian. They exposed each critter to high-energy blue light and then viewed them through a yellow filter to see if and how they glowed.

“One of the first salamanders we tested was the Eastern tiger salamander. We saw that it fluoresced really brightly, and that kind of got us hooked,” Lamb tells Mental Floss. “We started [to look] across salamander diversity, [and asked ourselves], ‘OK, how many species do we see within salamanders that biofluoresce?’ When we started to notice, ‘hey, it’s actually a lot of them!’, the question became, ‘can frogs do it?’ Then we looked at a relative of frogs, the caecelians—‘do they do it?’ And it seemed like biofluorescence in some form or fashion is present in all of these lineages.”

A biofluorescent Eastern tiger salamanderJennifer Y. Lamb and Matthew P. Davis

The various amphibians fluoresced in unique patterns depending on their skin’s coloration and markings as seen under normal white light. Some gleamed in blotches, others in stripes. A few animals' bones glowed. Lamb was surprised to see that salamanders’ bellies, which were usually red or orange under white light, glowed brighter than their backs after exposure to blue light.

“A lot of these newts have evolved what we call aposematic coloration, or warning colors. When they’re threatened by a predator, they’ll basically contort their bodies to show off their bellies as a warning,” Lamb says. “So it begs the question, if these bellies are also biofluorescent, then maybe some of their predators can visualize biofluorescence.”

The researchers intend their study to be a roadmap for further study into the fascinating ability. “Now that we know that this phenomenon exists across amphibians, there’s all kinds of interesting applications that future researchers may head towards,” Davis tells Mental Floss. For example, no one yet knows what kind of mechanisms allow amphibians to biofluoresce: In some groups it might be a color-based molecule or compound; in others, maybe something in their mucus.

A Cranwell's frog glows under blue light.Jennifer Y. Lamb and Matthew P. Davis

Scientists also don’t know exactly how different amphibians might visualize their own biofluorescence. Salamanders, frogs, and caecelians have rod cells in their eyes that are sensitive to green light, suggesting that they may have evolved green biofluorescence and the ability to see it at the same time, though further research is needed on that front.

“We have to be careful about not falling into the trap of only perceiving the world through our own eyes,” Lamb says. “Human vision is set to a particular set of wavelengths, and that’s not the case across all animal diversity. And that may not be the case in terms of these amphibians.”

A biofluorescent three-lined salamanderJennifer Y. Lamb and Matthew P. Davis

Finally, researchers are debating what purpose biofluorescence serves. In other animals, scientists have suggested it could play a role in communication, camouflage, or choosing a mate. Amphibians might use biofluorescence to locate each other in dense leaf litter.

“We’re hoping this study stimulates researchers to start looking at biofluorescence more broadly across the various different kinds of amphibian lineages that they may work on, so we can fill in the gaps in knowledge,” Davis says.

“There’s still a lot to learn about animal groups that we think we know,” he adds. “There’s still lots of interesting things out there to find that can help us rethink their life history and biology, and that may point us in new exploratory directions.”

Amazon's Under-the-Radar Coupon Page Features Deals on Home Goods, Electronics, and Groceries

Stock Catalog, Flickr // CC BY 2.0
Stock Catalog, Flickr // CC BY 2.0

This article contains affiliate links to products selected by our editors. Mental Floss may receive a commission for purchases made through these links.

Now that Prime Day is over, and with Black Friday and Cyber Monday still a few weeks away, online deals may seem harder to come by. And while it can be a hassle to scour the internet for promo codes, buy-one-get-one deals, and flash sales, Amazon actually has an extensive coupon page you might not know about that features deals to look through every day.

As pointed out by People, the coupon page breaks deals down by categories, like electronics, home & kitchen, and groceries (the coupons even work with SNAP benefits). Since most of the deals revolve around the essentials, it's easy to stock up on items like Cottonelle toilet paper, Tide Pods, Cascade dishwasher detergent, and a 50 pack of surgical masks whenever you're running low.

But the low prices don't just stop at necessities. If you’re looking for the best deal on headphones, all you have to do is go to the electronics coupon page and it will bring up a deal on these COWIN E7 PRO noise-canceling headphones, which are now $80, thanks to a $10 coupon you could have missed.

Alternatively, if you are looking for deals on specific brands, you can search for their coupons from the page. So if you've had your eye on the Homall S-Racer gaming chair, you’ll find there's currently a coupon that saves you 5 percent, thanks to a simple search.

To discover all the deals you have been missing out on, head over to the Amazon Coupons page.

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Treat Your Feline This Holiday Season With Fancy Feast’s Cat Food Advent Calendar

Fancy Feast/Chewy
Fancy Feast/Chewy

In anticipation of the holiday season, many children and adults get to unwrap mini presents each of the 24 days leading up to Christmas day, during what's known as Advent. Though Advent itself dates back to the 4th century, the version we know today, complete with the chocolate-filled calendars, was popularized in the early 1900s. And apparently it's no longer just for humans, because Fancy Feast is letting your feline roommate in on the fun with this unique cat food Advent calendar, now available at Chewy for $23.

For the 24 days leading up to Christmas, your cat will get to enjoy a variety of different wet foods, including favorites like grilled salmon, chicken, and more. There is even a unique ornament included with each calendar featuring a cat in the shape of a heart that can go right onto your tree. (Also, don't be surprised to find your actual cat making its way into the middle of your tree; they're known climbers.)

Now while you enjoy your Advent calendars from brands like LEGO, Funko, and more, your cat will be able to join in on the fun as well. To learn more about Fancy Feast's Feastivites Advent Calendar, head on over to Chewy.

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This article contains affiliate links to products selected by our editors. Mental Floss may receive a commission for purchases made through these links.