As The Giant Rhinoceros Beetle

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Oftentimes, knowledge about the background of authors can lead to a deeper and more thorough understanding of their work. Erin L. McCullough is a Postdoctoral Research Fellow at the Centre for Evolutionary Biology at the University of Western Australia (cite- https://www.researchgate.net/profile/Erin_Mccullough2). She was a PhD student at the University of Montana and has a recently updated blog in which her most recent papers and publications can be found (https://erinlouisamccullough.wordpress.com/). Much like his co-author, Robert Zinna is a Post-Doctoral Fellow and is a member of the University of Arizona where he runs helps run The Riehle Lab Mosquito research facility (http://riehlelab.arizona.edu/lab-members). Interestingly, he holds …show more content…
By avoiding fights that they are unlikely to win, the Giant Rhinoceros Beetles can both save energy and prevent injury. There is evidence that fight escalation is most likely to occur between two equally sized males, with smaller males simply retreating after sensing they are outmatched(paper). With smaller beetles retreating shortly after contact, some stimuli is received that allows them to assess their opponents. How Giant Rhinoceros Beetle assess their opponents is currently unknown, but visual stimuli has been ruled out due to the fights occurring most often at night. With the most likely source of sensory information not assisting in recognition at night, an alternative way to obtain might be through the use of the horn itself. The authors hypothesized that the “density of sensory hairs (and sensitivity) would correspond with the regions of the horns that are used most in both precombat assessment and actual combat” and “that hair density would increase distally along the length of the horn, and to be more abundant on the anterior of the horn” (paper). Basically, the authors are stating that the parts of the horn that are in contact with the opponent the most will have more sensory hairs on them allowing them to assess their opponents. Possessing such large insect weaponry without further …show more content…
Out of every encounter recorded 92% of them had beetles using their horn tips, 50% of them using the upper shaft of the horn, and 21% had the use of the middle shaft of the horn, and none were observed using the base of their horns. Additionally sensory hair density was “two times greater at the horn tips than on the lower shaft on the anterior face, and 7.5 times greater at the tips compared with the lower shaft on the posterior face” (). These results support the original hypothesis that sensory hairs would be most dense near the areas that the beetle used the most for combat. In addition, there was also an increase in hair in the distal and anterior regions of the beetle. Due to the presence of these sensory hairs, the horns were found to gather data about the size and condition of their opponents. This is most likely done through either mechanoreceptors or chemoreceptors, but no distinct pores were found on the tip or shaft of the hairs so mechanoreception seems like the more likely use for these hairs. Having determined that Giant Rhinoceros Beetles are able to assess their opponents prior to fighting and that the areas most often used during combat correlated with an increased density of these horns, it was determined that Giant Rhinocerous Beetles used the sensory

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