This blog entry was only possible with the help of this paper (Luis F. de Armas 1, Rolando Teruel 2, and František Kovařík), so thanks to the authors! The pictures are almost three years old while I’m writing this post. As always, my ID is based on the picture and location, so it can’t be 100% correct!
Scorpions are together with snakes and large spiders the most exciting animals to find for me! The combination of pincers and sting makes them incredibly defensive. The way they walk around, and how they react to anything close, is just fascinating. While they are mostly nocturnal and hard to find during the daytime, it is unfortunately pretty easy to find scorpions at night. A UV light torch will make them glow like ghosts in a cartoon (Daniel López-Cabrera, Gabriel Ramos-Ortiz, Edmundo González-Santillán, Rafael Espinosa-Luna, Characterization of the fluorescence intensity and color tonality in the exoskeleton of scorpions), and they will be visible from some meters of distance. This is how we found them, plus some other cool bugs! Coming soon. Unfortunately, this is also how smugglers find and catch scorpions in large scale. Way too many scorpions end up in the hobby.
C. edwardsii is the very first scorpion on picmybug! It is one of over 2,500 species belonging to the order Scorpiones. Almost half of all scorpions belong to the family Buthidae. Centruroides shares this family with some famous, “medically relevant” genera like Buthus, Leiurus, Androctonus, Tityus and Hottentotta. The genus Centruroides was described in 1890, by the German George Marx, who died only 5 years later, at the age of 56. There are at least 70 described species of Centruroides, and it might ring a bell when I say there might be some changes here and there (mhmh Heteropoda & Hierodula). Again, as many times before, we have similar looking species of variable color, so confusion is preprogrammed. Surprisingly none of the currently listed species are described by Marx. He was though a well recognized arachnologist, who worked mainly in the USA. He got wounded in the Civil war, and had health issues since then. Seven species of arachnids are named after him. You can read his obituary here on the website of the Biodiversity Heritage Library! It is amazing to be able to read something that is written 127 years ago. We might see his name again when I find a tick… One more finding: Marx’s collection of arachnids has been for sale for 1,500$ after his death. This would be a current value of over 50,000$. Find the source here.
It is no wonder, that our species has been known under different names, or been misidentified for a while. From the paper mentioned in the beginning, I took that C. edwardsii has also been described under the synonyms Scorpio (Atreus) degeerii (Gervais 1843), Rhopalurus danieli, and Centruroides margaritatus septentrionalis. The authors also mention that C. margaritatus looks very similar, but you can distinguish both by the profusely pilose pedipalps – very hairy hands. Edward Hairyhands, and this is much easier to me, occurs in a different region (look at page 6 in the paper) compared to C. margaritatus, and thus I decided mine must be C. edwardsii. I can see hairy hands, but I cannot see a difference between photos of both species on the internet (what of course means nothing). We found them in North West Costa Rica.
About the fluorescence: It is well known that scorpions show this effect, and it is also known which substances cause the fluorescence (mostly β-carboline and 4-methyl-7-hydroxycoumarin, rather complex molecules), but we know very little why they do this. Some animals, and perhaps also scorpions, are able to see UV light (what we don’t see), but why would a scorpion want to glow like a bulb? Either they are able to identify a partner (and also distinguish between other species?), or do they attract prey, like the snot mob on our huntsman spider? Moths and other insects might be attracted to a glowing scorpion, they might confuse it with a flower. Even large mammals like the deer are able to see ultraviolet, and this can also make sense for the scorpion – they wouldn’t be trampled by large mammals in the dark when they are visible. Perhaps is the reputation of a scorpion good enough, so that good visibility is of much more benefits than it has risks. Self-confidence they have! Finding a partner, be safe from gigantic mammals who wander around, and attract food, versus being visible for predators. Predators are manifold, see some listed here . Birds, lizards, centipedes, shrews, coatis, bats, other arachnids… The hobby of keeping exotic animals might provide some information about the biology of such animals, but I’m not sure if this topic can be lighted in a terrarium. You neither have a deer around nor do you have the space to obtain if a moth was attracted by fluorescence or not. Also, you usually wouldn’t have much UV light in your room. Interestingly, a scorpion after a molt has a lower fluorescence. While the exoskeleton is still soft for a while, scorpions wouldn’t eat and are pretty much defenseless for a few hours. Good idea to hide in the dark during that stage, isn’t it?
Centruroides are commonly called Bark scorpions, and when you listen closely… no you won’t hear them bark. They live on/ under the bark of trees. So let’s see some photos:
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