UV Fluorescence in Nature

[pufferchung]

UVIVF of Virginia Opossum (Didelphis virginiana)
Here is the observation: https://www.inaturalist.org/observations/100580271

This picture is not shot in completely darkness because my neighbor’s backyard

light was on…My camera lens has additional filters on but still some light leak there.

[pisum]

@pufferchung

Another interesting UVIVF that I’ve noticed is UVIVF of rat (Genus Rattus).

yup. i discovered fluorescent rats myself a year or so ago.

@pisum

rat: https://www.inaturalist.org/observations/164137122

apparently the peak absorption wavelength for Rattus is ~365nm (and it emits greenish blue, although our cameras seem to both have captured a deeper blue), and i wonder if that’s why they glow so brightly for me using a 365nm light?

@pufferchung

UVIVF of Virginia Opossum (Didelphis virginiana)
Here is the observation: https://www.inaturalist.org/observations/100580271

that’s a nice shot showing the rainbow fluorescence that is apparently characteristic of opossums and shows the wide range of colors that tryptophan metabolites can fluoresce.

[pufferchung]

“apparently the peak absorption wavelength for Rattus is ~365nm (and it emits greenish blue, although our cameras seem to both have captured a deeper blue), and i wonder if that’s why they glow so brightly for me using a 365nm light”
That’s very interesting!
You are right.
For UVIVF, I only used my regular DSLR camera and lens.
I was told by professional UV photographers (some are researchers from Ultraviolet photography) to use regular camera + lens for UVIVF picture.
I have a special full spectrum camera and special UV lens for UV photography, next time I’ll try to get a picture of dead rat with an UV camera…see if it’s greenish blue.

[pufferchung]

Another interesting UVIVF observation is a juvenile green anole (Anoles carolinensis).
Only the juveniles glow blue, but adults don’t glow at all. No one knows why neither…
Here is the observation: https://www.inaturalist.org/observations/94805108

[pisum]

@pufferchung

Only the juveniles glow blue, but adults don’t glow at all. No one knows why neither…

in your observation, you made a comment that the blue of the anole in the photo was actually more of green. that’s similar to the rats that were captured as blue but which i’m sure were more greenish. (the white balancing in the cameras is causing the shift.) since reptiles aren’t too far from mammals, i’d guess that the anole fluoresced due to tryptophan metabolites.

as for why the juvenile fluoresced but not the adult, i’m not sure, but if i were a scientist, i would explore a couple of paths:

1. the juvenile green anole here looks sort of brown. since green anoles can shift between green and brown, i wonder if it’s the brown pigment that’s fluorescing, whereas the green doesn’t? (you can sort of see how its greenish sides show up darker in the fluorescent image.) there’s no indication of what color the adult was expressing when you shined the UV light on it. but maybe there’s a difference if you shine a light on a green green anole vs a brown green anole? (the article mentioned a case where white minks did not fluoresce but brown minks did, and our rats are brown. so maybe the tryptophan metabolites are brown under regular light?)
2. the skin of the juvenile anole seems a little pale – maybe like it’s ready to molt. you can see around its right shoulder where it seems like there might a tear in the skin, and you can also see small oval spot on its left femur. under UV, these areas show as brighter spots. so i wonder if these spots are allowing the light to get to the tissue or skin underneath? in other words, is the extra layer of skin on top blocking some of the light transmission? and is it possible that juveniles have thinner skin that allows the UV to get to whatever is underneath that fluoresces? if you were to hit a newly-molted or molt-in-progress adult with UV, would you be able to see some fluorescence?

[pufferchung]

Very interesting! Thank you so much for the information!
Too bad it’s winter now, all the green anoles in my backyard disappeared.
I’ll try to get some UVIVF pictures of green anole next year.

[WildEdges]

I’ve edited my post to show the wavelength.

[WildEdges]

I’ve got some Bulla genus shells here that also glow. I’ll take a photo when I’ve found them but my 6yr old’s museum seems to have most of my collection on loan at the moment.
I’m not sure if fossils count as nature but have a look at this video showing the effects of UV light on fossil shells (about 13mins in) https://www.youtube.com/watch?v=QCbdoigd0qQ&t=1160s

[cthawley]

Yes, I remember seeing this observation a couple of years ago. Shed anole skin does show as pretty “bright” white under UV light (similarly to what a lot of other whites do). I’ve used UV ID tags on anoles a fair amount but only on adults and never seen any dramatic UV responses (a couple of dots here or there), although the UV lamps we used are to make the tags floresce, not the lizards and I think they are higher than 365.

Juvie anoles definitely have thin skin in general that is easily damaged.

[sebastiandoak]

I mostly use my UV light to find arachnids, especially small harvestmen there are a couple species which I mostly only see when looking with a UV light.

One of my fave non-arachnid examples is this thornfish.

Kaihua also seems extremly glowy compared to other flowers in the bush.

[jasonhernandez74]

@teellbee

I once caught ringworm when volunteering at a small pet rescue.

Did you upload the observation?

@pisum

shows the wide range of colors that tryptophan metabolites can fluoresce

But do the fluorescent colors, themselves, have a biological function in mammals? Like the UV patterns on flowers that pollinators can see?

[teellbee]

@pisum

here’s a video that sort of shows that happening: https://youtu.be/aJh5bosgFQQ?t=187 . i think the phenomenon is called the Kautsky effect. it would be interesting to ask students to develop hypotheses for why it happens.

Thank you, for your insights and advice.

I just got a UV light recommended in a different topic by @tiwane *(“I use the uvBeast V3 365nm MINI ”)

It is so much superior to the 4 UV* flashlights and tube light I still have. I tried the Kautsky effect with it and it was very noticeable on a geranium leaf.

I also note that I got much more vivid colors from the same mosses, leaves, and onions I tried last week with the old flashlights.

Edit: *including a relatively new uvBeast v1, which is much less effective than the uvBeast v3.

[teellbee]

As most of you already know, UV light can harmful (especially to eyes and skin). For reference, here is snippet about UV wave length harm chart from Lawrence Berkeley Lab:

https://ehs.lbl.gov/resource/documents/radiation-protection/non-ionizing-radiation/ultraviolet-radiation/

Unlike the skin, the eyes do not develop a tolerance to repeated exposure to UV. The absorption of UV-A radiation in the lens of the eye may produce progressive yellowing with time and may contribute to the formation of cataracts, causing partial or complete loss of transparency.

Band	Wavelength (nm)	Primary Visual Hazard	Other Visual Hazards	Other Hazards
UV-A	315–400	Cataract of lens		Skin cancer, retinal burn
UV-B	280–315	Corneal injuries	Cataract of lens, photokeratitis	Erythema (sunburn), skin cancer
UV-C	220–280	Corneal injuries	Photokeratitis	Erythema, skin cancer
Far UV	190–220	Absorbed completely in the atmosphere
Vacuum UV	40–190	Absorbed completely in the atmosphere

Of course, whenever we are out in daylight, we are exposed to UV light and may notice the effect as freckles or a tan and (eventually) cataracts. Still, it’s worth being aware of the accumulative effects of UV exposure and to avoid over doing it - exposing eyes (ourselves or other creatures) to UV light.

FWIW, this article goes into a lot of other uses and technical info and detail about the effects of different UV wavelengths.

[scharf]

With UV – notice the sedges fluorescing blue behind the mushrooms.

With flash

Observation: https://forum.inaturalist.org/t/uv-fluorescence-in-nature/47310/54?u=scharf

[lothlin]

Oh yeah some plants definitely have some crazy reaction too - you can see the red color the moss was turning in my picture.

What are those shrooms, some kind of cortinarius it looks like? That is a crazy bright yellow.

[scharf]

Moss is always super red. Young, growing plants also fluoresce super red, especially linden tree leaves. Leaf galls of various kinds also fluoresce white and show up much more brightly under UV than under full spectrum light.

As to what type of mushroom is in the observation. . . I don’t know. Nobody has taken a stab at identifying it yet. Maybe in a few weeks I’ll have the time to give my unidentified mushroom observations more attention.

[lappelbaum]

Some fluorescent lichens lit with 365nm UV flashlight photographed in detail under dissecting microscope
Texas Wart Lichen Pertusaria texana (orange)
https://www.inaturalist.org/observations/153504787
https://www.inaturalist.org/observations/153504792
https://www.inaturalist.org/observations/152743521
Spotted Wart Lichen Pertusaria paratuberculifera (yellow)
https://www.inaturalist.org/observations/152743518
Red Heads Ramboldia russula (yellow)
https://www.inaturalist.org/observations/153504791
https://www.inaturalist.org/observations/153504786
Glowing Script Graphis lucifica (yellow)
https://www.inaturalist.org/observations/152671294
https://www.inaturalist.org/observations/152671295
Crabseye Lichens Ochrolechia sp. (yellow)
https://www.inaturalist.org/observations/152773079
Rim Lichens Lecanora sp. (orange)
https://www.inaturalist.org/observations/152773075
Barnacle Lichens Thelotrema sp. (orange)
https://www.inaturalist.org/observations/152743522
mystery lichen (orange)
https://www.inaturalist.org/observations/152743527

[lappelbaum]

@pisum

so if you shine a UV light on something and see other colors emerge, you’ve almost certainly got fluorescence. but if you see the same purple or pale blue that your flashlight emits, then it’s possible that’s just reflection.

here’s a spider observation of mine: https://www.inaturalist.org/observations/164137128 . if you look at the spider, it’s showing up as the same pale blue that my flashlight emits. so it’s possible that it’s just reflecting the pale blue light in that case. (there might also be some faint fluorescence, but i’m not sure.)

With 365nm I notice some of the lichens (or parts of lichens) show up as pale blue while others are black or barely visible as kind of an olive brown. I haven’t posted these on iNat yet:

[conorflynn]

It’s cool that so many species fluoresce, but is it just some lichen that fluorescence helps to ID? Are there many species that it helps to ID? Any other taxa?

[conorflynn]

@pufferchung thank you for sharing the article from the Wildflower Center with your beautiful photos! ( https://www.wildflower.org/magazine/native-plants/a-different-light )

That article helped me understand the difference between UV reflective and UV-induced fluorescence (UVIVF) images. However, I think many people, including the author of that article, are still confused about the biological meaning of UVIVF. For example, the False Gromwell writeup implies that insects can see UVIVF to help find flowers that are otherwise inconspicuous.

But UVIVF is never normally visible… except maybe as an added glow. The best example is laundry detergent that makes whites brighter. By adding a UVIVF chemical to the detergent, clothes actually slightly glow in any UV light, making them appear brighter.

Photographs of UVIVF in darkness show the extra brightness we see in sunlight, but probably don’t notice.