Ultra-violet light can reveal hidden colors on lichens. These revealed colors tell us about the adaptations of lichens, their species identity, and are simply aesthetically beautiful.
These pixie cup lichens (cladonia spp.) in Image 1 show colors ranging from red, orange, green, turquoise, indigo, violet, and more. This medium patch is about 8″ in diameter host to 5+ pixie cup species, and 3 moss species at the foot of a conifer.
Image 1. Pixie cups (Cladonia spp.) species with UV light.
I prefer UV light that emits at 365 nm vs 395 nm or UV-B rays. The 365 nm light is safer than UV-B and gives a cleaner illumination than 395 nm which gives a purple wash over everything. These colors are revealed by a UV flashlight emitting at 365 nm wavelength with a ZWB2 filter that blocks visible light.
UV light can be harmful to your eyes and skin with prolonged exposure! Never shine UV light in anyone’s eyes as it could cause permanent damage with enough exposure. I recommend mature children aged 10 and older to handle the UV flashlights, but not younger than that, generally.
Best safety practices include using safety glasses to block the UV light from entering your eyes. I prefer this model since it fits over glasses and is clear in tint, rather than the standard yellow, see Link 1. The standard for eyeglass safety is ANSI Z87 and these glasses are compliant. Many modern glasses lenses block UV inherently or are coated to block UV light.
Link 1.
https://www.amazon.com/NoCry-Eyeglasses-Wraparound-Protective-Approved/dp/B07GBF8B2V/?th=1
I prefer the brand Convoy and use their S12 model for teaching, see Link 2 below, “Convoy S12 UV 365nm 21700 flashlight” for $34.48 (May 21, 2025). For my driver, I selected “constant current” for even output, but “Linear” is also fine.
Link 2. URL for Convoy S12 UV flashlight without ZWB2 filter
https://convoylight.com/collections/uv-light/products/convoy-s12-uv365nm?data_from=collection_detail
I highly recommend buying the ZWB2 filter, since it improves your experience, though it isn’t essential for $1.97. You have to unscrew the flashlight and replace the filter on your own, which is simple to do. Convoy can’t ship the flashlight with the filter to the US because there is patent litigation going on.
Link 3. URL for ZWB2 filter for S12
The S12 flashlight uses a special battery, 21700. This needs to be ordered either as an add-on or through another source. From the current list, I would recommend the battery, “Samsung INR21700-50S2 5000mAh” for $ 4.46. Going for main brand batteries is the preferred option.
You also need a special charger for the 21700 battery. From the store list I recommend this one, see Link 4, “Liitokala Lii-S2 charger” for $12.22 (May 21, 2025). You can use any other battery charger that also fits a 21700 battery, but confirm the compatibility and research reviews looking for issues.
Link 4. Liitokala Lii-S2 charger
https://convoylight.com/products/liitokala-lii-s2-charger?data_from=search_detail
I like having a backup battery for my flashlight so I can always have a charged one on hand. So I recommend buying 2 batteries if you are able.
With the UV flashlight kit set up through the above links, a vibrant unseen world will reveal itself, see Image 2! Many organisms in nature have adaptations to manage UV light, as too much UV light can be damaging for their existence.
Image 2. Lichens with UV light on rocks near Chester Creek, Duluth, MN.
Image 3. Nostoc, a cyanobacteria found in some lichen species, is found here free living anad glowing red and light blue under UV light.
I hope you can go out in the world end explore the hidden world of ultra-violet light!
Tanner Barnharst
“Midwest Mycologist”
Leave a Reply