Lychas mucronatus: the Ornate Bark Scorpion

All too often, my encounters with creatures in the wild are too brief: some take flight, while others hop, jump, scurry, or slither away, sometimes even before I am able to photograph them. Often, I let a subject go because I do not wish to stress it too much. But once in a while, everything comes together perfectly, giving me the time to fiddle around and play with photographic composition and lighting — this Lychas mucronatus let me do just that.

Lychas mucronatus (Fabricius, 1798) portrait, backlit with a wirelessly triggered flash

In my previous post (posted over a year ago), I had written about the opportunity I had to drive Dr. Peter Jäger around the karst mountains in Laos, and my personal search for the giant huntsman spider, Heteropoda maxima. We were accompanied by Jonas Ewert, a biologist who worked in and around Thakhek, on one of our nightly excursions. He found this beautiful specimen on a tree trunk, and after he and Dr. Jäger had taken some photographs of it, I spent about twenty minutes playing with backlighting, using a wirelessly triggered  off-camera flash.

Dorsal view of Lychas mucronatus (Fabricius, 1798)

Scorpions are categorised under class Arachnida, together with harvestmen, mites, solifuges, spiders, and ticks. Lychas mucronatus is a member of the largest scorpion family: Buthidae. I wonder how it got its other common name — the Chinese Swimming Scorpion — because I have not come across any documented evidence of the species’ ability to swim.

One of the interesting peculiarities of scorpions is their blue-green photoluminescence under ultraviolet light, the intensity of which varies between ages and species. This is due to the presence of two fluorescent chemical compounds (Stachel et al, 1999; Frost et al, 2001) in the cuticle, which is a chitinous protective structure in arthropod exoskeletons. Dr. Jäger’s headlamp had a UV LED on it, so we were able to photograph the phenomenon.

Lychas mucronatus (Fabricius, 1798) fluorescing under UV light

The actual function of this photoluminescence remains unknown, although several hypotheses have been made regarding this (Wanhede, 2004). It might even be possible that this has no function whatsoever, and is perhaps a byproduct of biochemical processes. Nevertheless, it is still a matter of much scientific interest, and field scientists’  favour UV lamps and flashlights to detect scorpions (Stahnke, 1972).

Lychas mucronatus is a widespread species in China and Southeast Asia. A quick Google search reveals that it is popular in the pet trade. Its venom has been the subject of several recent studies, and contains a component called mucroporin that has been shown to have potential as an antibacterial and virucidal agent (Dai et al, 2008; Li et al, 2011; Zhao et al, 2012).

Close-up of tail and stinger: Lychas mucronatus (Fabricius, 1798)

As I mentioned in my last scorpion post, I know relatively little about them and have only had infrequent scorpion sightings, so it is always exciting when I come across one. I hope to find this species in the Philippines, where I currently live.

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References:

1. Dai, C., Ma, Y., Zhao, Z., Zhao, R., Wang, Q., Wu, Y., Cao, Z., and Li, W. 2008. Mucroporin, the first cationic host defense peptide from the venom of Lychas mucronatus. Antimicrobial. Agents Chemother. 52: 3967–3972.
2. Frost, L. M., Butler, D. R., O’Dell, B., & Fet, V. 2001. A coumarin as a fluorescent compound in scorpion cuticle. Scorpions 2001 In Memoriam Gary A. Polis, 363-368.
3. Stahnke,, H. L. 1972. UV light, a useful field tool. BioScience, 22(10): 604-607.
4. Stachel, S.J., Stockwell, S.A. & VanVranken, D.L. 1999. The fluorescence of scorpions and cataractogenesis. Chem. Biol., 6: 531-539.
5. Wankhede, R. A. 2004. Extraction, Isolation, Identification and Dist ribution of Soluble Fluorescent Compounds from the Cuticle of Scorpion ( Hadrurus arizonensis). Retrieved November 16, 2017, from http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.123.2474&rep=rep1&type=pdf
6. Li, Q., Zhao, Z., Zhou, D., Chen, Y., Hong, W., Cao, L., Yang, J., Zhang, Y., Shi, W., Cao, Z., Wu, Y., Yan, H., and Li, W. 2011. Virucidal activity of a scorpion venom peptide variant mucroporin-M1 against measles, SARS-CoV and influenza H5N1 viruses. Peptides 32: 1518–1525.
7. Zhao, Z., Hong, W., Zeng, Z., Wu, Y., Hu, K., Tian, X., … Cao, Z. 2012. Mucroporin-M1 Inhibits Hepatitis B Virus Replication by Activating the Mitogen-activated Protein Kinase (MAPK) Pathway and Down-regulating HNF4α in Vitro and in Vivo. The Journal of Biological Chemistry, 287(36), 30181–30190. http://doi.org/10.1074/jbc.M112.370312

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