5/29/2023 0 Comments Scorpion optical isolatorSpecial thanks go to Greg Blass for making the initial forays into scorpion UV-stimulated behaviour. Thanks also to Jay Vinnedge for assistance with the eye-block behavioural trials. We thank Dr Douglas Mock, Dr Ingo Schlupp, Dr Mariëlle Hoefnagels, Dr Eric Abraham, Elise Knowlton, Andrea Jordan and Tristan Barker for valuable advice, technical support and consultation services. The behaviour of eyes-blocked scorpions under UV was less affected. Also, scorpions significantly altered their behaviour under green light when their eyes were blocked by foil compared to scorpions without their eyes blocked. Furthermore, their response to UV was greater than what would be expected based on previously published physiological studies of retinal sensitivity. Scorpions moved in sporadic bursts under cyan-green and UV wavelengths of light compared to yellow light and no light. Twenty of the 40 animals had valid trials for all four Discussion 395 nm) had a disproportionate number of crossings early in their excursions compared to no-light controls (Fig. 2). The distribution of the first 20 crossings for the 10 min trials for scorpions under 395 nm and no light showed that stimulated animals (e.g. Animal movements were noticeably sporadic under certain wavelengths of light compared to no-light trials. Most trials (70%) met the criteria for validity (12 or more ICIs of less than 45 s). We filmed the scorpions from beneath a Wavelength Response Trials The room temperature remained within a range of 21–24 ☌, and the room lighting followed a 16:8 h light:dark cycle. We fed the scorpions one waxworm ( Achroia grisella) every 3–4 weeks and watered them twice per week. In the laboratory, we kept the animals in individual glass jars with about 2–3 cm of sand covering the bottom. We used male and female P. utahensis collected during March 20 from a sandy region about 30 km southeast of Monahans, Texas. Scorpions may use this information to detect shelter, as blocking any part of the cuticle could diminish the signal. We therefore propose that the cuticle may function as a whole-body photon collector, transducing UV light to cyan-green before relaying this information to the central nervous system. Other studies indicate that photosensitive elements in scorpion tails are sensitive to green light. These results suggest an active role for fluorescence in scorpion light detection. Scorpions with blocked eyes were much less likely to move under 505 nm than under 395 nm and were much less likely to move under 505 nm than were control animals (those without their eyes blocked). Next, we ran trials under 395 and 505 nm on scorpions with their eyes blocked. In our experiments, however, scorpions responded most intensely (abrupt bouts of locomotory activity) to 395 nm and 505 nm. Based on the eye sensitivity data, we predicted maximal response to 505 nm, followed by lower responses to 395 and 565 nm. Scorpions are negatively phototactic, and we used this behaviour to assay the responses of desert grassland scorpions, Paruroctonus utahensis, to 395 nm UV light, 505 nm cyan-green light, 565 nm green light and no light within small, circular arenas. Previous studies of four species from three families have shown that scorpion lateral and medial eyes are maximally sensitive to green light (around 500 nm) and secondarily to UV (350–400 nm). The function of this fluorescence is a mystery. Scorpions are largely solitary, nocturnal arachnids that glow a bright cyan-green under UV light.
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