Date of Award
Bachelor of Science
Biological Neuroscience, Neuroethology, Dragonflies, Insect Audition
To date there is no published evidence that dragonflies (Odonata), have a nervous system equipped to process auditory stimuli. Even with considerable research on these creatures due to their specialized vision and flight mechanics, there is no evidence that dragonflies have ears or even auditory neurons. Last year student Andrew Hamlin and Professor Robert Olberg recorded neuronal responses in the dragonfly to auditory stimuli of 100-2000Hz sounds (Olberg and Hamlin, unpublished). This year our research was aimed at understanding a sensory modality that was previously unknown in dragonflies, the sense of hearing. In order to investigate this question we used behavioral and electrophysiological studies on the Aeshnid dragonfly Anax junius and various Aeshna species. Behaviorally, dragonflies were loosely tethered to a standing mount allowing free movement while computer-generated sound stimuli were played to the animal and video-recorded. Electrophysiological studies were done by extracellular recording of the ventral nerve cord to detect neuronal activity in response to these computer-generated frequencies (50Hz – 22KHz). This study suggested that sound waves do stimulate an auditory sense through a tympanum or external ear in dragonflies. This is an extremely subtle sense in these highly visual creatures but it is consistent in the far field of a sound wave meaning the response is characteristic of an external ear and not mediated by mechanoreception or sensory hairs.
Shaw, Brian, "The Exploration of Neuronal Responses to Auditory Stimuli in the Dragonflies, Anax junius and Aeshna Constricta" (2018). Honors Theses. 1591.