Fluorescence in Psedoscorpions?

I noticed the pseudoscorpion was glowing fluorescent under uv light.

Pseudoscorpion fluorescing

Pseudoscorpion fluorescing

I was sure fluorescence had never been recorded in pseudoscorpions before, unlike real scorpions which are widely known to fluoresce. Although as yet there is little supporting evidence for any of the postulated evolutionary reasons for the fluorescence, which is widely believed to be due to the molecule 4-methyl-7-hydroxycoumarin (Frost et al) as the cross linkages in the hardening exoskeleton form.

Initially I was excited by the prospect of describing something new to science in this domain but a couple of things got me wondering. Why did it fluoresce only on the underside, why was it motionless and why didn’t I notice this earlier – was this because I had failed to notice the underside?



The following day the pseudoscorpion was still motionless, I was now inclined to think it was dead. It was, but sure enough it still fluoresced on the underside. I was determined to find out why, but these little pseudoscorpions were not that easy to find. I had only ever found one group of this particular species in the past in Eucalyptus leaf litter.

I crushed the dead pseudoscorpion in sterile water and did a streak on nutrient agar plates. Sure enough, over night bacterial colonies appeared that exhibit strong fluorescence in the same colour as observed in the pseudoscorpion. Presumably a Pseudomonas of some sort as it had the distinctive Pseudomonas odor.

fluorescent bacteria

Strong fluorescence on nutrient agar.


Updates to follow as I identify the organism.


fluorescent bacteria

fluorescent bacteria plated on nutrient agar
















Frost, L.M., D.R. Butler, D. O’Dell & V. Fet. 2001.  A coumarin as a fluorescent compound in scorpion cuticle. Pp. 365–368. In Scorpions 2001: in Memoriam, Gary A. Polis. (V. Fet & P.A.Seldon, eds.).  British Arachnological Society, Burnham Beeches, Buckinghamshire, UK.


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