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Author Topic: Why do scorpions glow under UV light?  (Read 10849 times)

Offline chris

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Why do scorpions glow under UV light?
« on: 20/03/2010 11:32:57 »
One way to spot scorpions at night is with a UV light source - adults glow a greeny blue. Why?

Chris


 

Offline RD

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Why do scorpions glow under UV light?
« Reply #1 on: 20/03/2010 14:42:28 »
Fluorescence is possibly a form of sunscreen: converting harmful UV into harmless visible light,
(other forms of sunscreen convert the UV into heat, but that would be undesirable in a very hot environment). 


[less likely explanation] If the visible glow is long lasting it may provide illumination when the scorpion goes into its burrow ...

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[scorpions] are ... fossorial
http://en.wikipedia.org/wiki/Scorpion#Life_and_habits
« Last Edit: 20/03/2010 14:56:34 by RD »
 

Offline RD

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Why do scorpions glow under UV light?
« Reply #2 on: 23/03/2010 00:33:24 »
This chap thinks scorpion fluorescence could just be accidental ...

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Wildlife - scorpions
Expert: Jim Harris - 8/24/2004

Question
Is it true that some scorpions glow in the dark?

Answer
... scorpions do "glow" when exposed to a black light. WHY does this happen?  Well, the jury  is still out where that's concerned. Most likely it's an accidental side effect of the chemicals making up the exoskeleton.  One popular theory is that it's a form of built-in sunscreen to protect the scorpion from ultraviolet rays.  Personally, I have my doubts about this; scorpions tend to be nocturnal and I can't see any reason they would need sunblock.  So, as far as I know, the situation is still a mystery. 
http://en.allexperts.com/q/Wildlife-2507/scorpions.htm


The fluorescence could just be a neutral side-effect ...

Quote
Some protein or small molecules in cells are naturally fluorescent, this is called intrinsic or autofluorescence
http://en.wikipedia.org/wiki/Fluorescence_in_the_life_sciences
« Last Edit: 23/03/2010 01:02:04 by RD »
 

Offline Geezer

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Why do scorpions glow under UV light?
« Reply #3 on: 23/03/2010 05:45:13 »
Is it 'cos it makes them look cool when they go down the disco? Or maybe it's just because they have really bad dandruff?
 

Offline chris

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Why do scorpions glow under UV light?
« Reply #4 on: 23/03/2010 08:28:10 »
I did some poking around and found that the fluorescence is caused by the accumulation in the mature exoskeleton of a chemical called beta-carboline, which glows under UV.

I am not sure what role this substance performs normally, scorpions not being known as avid clubbers or disco-goers.

chris
 

Offline LeeE

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Why do scorpions glow under UV light?
« Reply #5 on: 23/03/2010 16:45:03 »
Actually, there might be some mileage in the sunblock theory precisely because they tend to be nocturnal.

If the scorpion is generally nocturnal its metabolism will be 'tuned' for operating most efficiently at relatively low temperatures (when compared with daytime temperatures) and in the absence of solar radiation.  However, it may then run the risk of overheating if, for any reason, it has to be active during the daytime e.g. if it's disturbed.  In this case, the fluorescence may help to prevent overheating by more effectively re-radiating solar energy.  At the same time, there won't be much risk of UV illumination during the night so there'll be little risk of the fluorescence giving it away while it's hunting.

There's also the possibility that although the fluorescence is swamped, at least to our eyes, by the ambient light level during the daytime, it may be visible to certain predators (I believe that both birds and rodents can see UV light) and act as a deterrent by scaring them off or by warning them that they're poisonous in the same way that many other brightly coloured creatures clearly advertise their poisonous nature to avoid being eaten.  On the other hand though, if a UV aware predator is not scared by the fluorescence and the poison then it's just going to act like a huge sign saying "Food Here!!"
 

Offline RD

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Why do scorpions glow under UV light?
« Reply #6 on: 23/03/2010 17:07:19 »
...I believe that both birds and rodents can see UV light) and act as a deterrent by scaring them off or by warning them that they're poisonous in the same way that many other brightly coloured creatures clearly advertise their poisonous nature to avoid being eaten. 

UV vision isn't a factor unless the scorpion is fluorescing (lower energy) UV, (apparently it's only emitting visible light).
« Last Edit: 23/03/2010 17:15:24 by RD »
 

Offline LeeE

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Why do scorpions glow under UV light?
« Reply #7 on: 23/03/2010 17:30:50 »
Fairy nuff.
 

Offline Geezer

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Why do scorpions glow under UV light?
« Reply #8 on: 25/03/2010 00:01:59 »
Is this phenomenon unique to scorpions?
 

Offline RD

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Why do scorpions glow under UV light?
« Reply #9 on: 25/03/2010 01:37:38 »
Is this phenomenon unique to scorpions?

Allegedly this is a video of jellyfish fluorescing under UV ...
feature=related

but they could actually be bioluminescent which is not the same thing: (no UV required).
« Last Edit: 25/03/2010 01:40:38 by RD »
 

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Why do scorpions glow under UV light?
« Reply #9 on: 25/03/2010 01:37:38 »

 

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