# What makes scorpions glow under UV light?

What substance (or class of substances) is responsible for the neon blue-colored fluorescence we observe when we shine UV light on scorpions?

Do note, I want to know what substance makes them glow and not why they glow... the latter being more suited for the Bio.SE.

• Interesting link here sciencedirect.com/science/article/pii/S1074552199800854 "The fluorescence of scorpions and cataractogenesis" – user1945827 Apr 15 '17 at 9:14
• ever-so-slightly helpful info in video: "a nitrogenous substance in its cuticles" More helpful, but WIRED is not a scholarly reference: Two compounds are involved in scorpion UV fluorescence: beta-carboline and 4-methyl, 7-hydroxycoumarin.. – uhoh Apr 15 '17 at 15:01
• I'm voting to close this question as off-topic because identifying the specific substance (quite possibly a complex macromolecule) is more suited for Bio.SE. – Zhe Apr 16 '17 at 0:31
• I think that it is a chemistry question, the chromophore is not unlike an indole /trp molecule in a protein, and properties of proteins is to me is part of chemistry. If as chemists we do not embrace new areas our subject will fade away. – porphyrin Apr 16 '17 at 7:44
• @Zhe How is asking which specific substance fluoresces not chemistry? I strongly disagree with your idea that it isn't. – matt_black May 25 '17 at 13:29

## 1 Answer

As mentioned in this comment, which links to this paper, and this comment, which links to this Wired article, there are at least two molecules:

$\beta$-carboline:

4-methyl-7-hydroxycoumarin:

$\tiny\text{Yes I poached those comments, they could have been answers.}$

• I think the brevity of this answer (which fully answers the question as stated) shows precisely why the question hardly contains any chemistry. Not that there's any biology in it, either. I think it is still chemistry, but all in all, not a very useful question. Now, if it asked about why these molecules fluoresce, that would be different. – orthocresol May 25 '17 at 19:57
• @orthocresol I agree that the answer would be better if it described some of the background, like how we know these are the culprits. What do their fluorescent spectra look like, for example. Fleshed out, I think it would make a good answer. – matt_black May 25 '17 at 21:13
• @matt_black There is a figure from the paper I can add, and I can also give a crude comparison against some calculations. Would that be interesting? – pentavalentcarbon May 25 '17 at 21:23
• @matt_black Yet, the question was not asking about how they were identified. The question only asks about what they are, and the answer to that is "they are X and Y". – orthocresol May 25 '17 at 23:20
• @orthocresol I agree in principle with your comments, but it would be interesting to know if these molecules are just in the protein as is, or if they are chemically linked to an amino acid for example, which would be my guess. So there is much more to this yet. It would also be interesting to know why these compounds are there, are they photo-protectors for example, or just a byproduct of metabolism or what? Nature is generally not wasteful. – porphyrin May 26 '17 at 8:56