Gordon SD. ter Hofstede HM. 2018. The influence of bat echolocation call duration and timing on auditory encoding of predator distance in noctuoid moths. The Journal of Experimental Biology

by Shira | Feb 2, 2018 |

Abstract: Animals co-occur with multiple predators, making sensory systems that can encode information about diverse predators advantageous. Moths in the families Noctuidae and Erebidae have ears with two auditory receptor cells (A1 and A2) used to detect the echolocation calls of predatory bats. Bat communities contain species that vary in echolocation call duration, and the dynamic range of A1 is limited by the duration of sound, suggesting that A1 provides less information about bats with shorter echolocation calls. To test this hypothesis, we obtained intensity-response functions for both receptor cells across many moth species for sound pulse durations representing the range of echolocation call durations produced by bat species in northeastern North America. We found that the threshold and dynamic range of both cells varied with sound pulse duration. The number of A1 action potentials per sound pulse increases linearly with increasing amplitude for long duration pulses, saturating near A2 threshold. For short sound pulses, however, A1 saturates with only a few action potentials per pulse at amplitudes far lower than the A2 threshold for both single sound pulses and pulse sequences typical of searching or approaching bats. Neural adaptation was only evident in response to approaching bat sequences at high amplitudes, not search phase sequences. These results show that, for short echolocation calls, a large range of sound levels cannot be coded by moth auditory receptor activity, resulting in no information about the distance of a bat, although differences in activity between ears might provide information about direction.   Gordon and ter Hofstede. 2018  The influence of bat echolocation call duration and timing on auditory encoding of predator...

Gordon SD, Windmill JFC. 2015. Hearing ability decreases in ageing locusts. J. of Experimental Biology. 218:1990-199

by Shira | Oct 9, 2016 |

Insects display signs of ageing, despite their short lifespan. However, the limited studies on senescence emphasize longevity or reproduction. We focused on the hearing ability of ageing adult locusts, Schistocerca gregaria. Our results indicate that the youngest adults (2 weeks post-maturity) have a greater overall neurophysiological response to sound, especially for low frequencies (<10 kHz), as well as a shorter latency to this neural response. Interestingly, when measuring displacement of the tympanal membrane that the receptor neurons directly attach to, we found movement is not directly correlated with neural response. Therefore, we suggest the enhanced response in younger animals is due to the condition of their tissues (e.g. elasticity). Secondly, we found the sexes do not have the same responses, particularly at 4 weeks post-adult moult. We propose female reproductive condition reduces their ability to receive sounds. Overall our results indicate older animals, especially females, are less sensitive to sounds. Gordon SD, Windmill JFC. 2015. Hearing ability decreases in ageing locusts. J. of Experimental Biology....

Mortimer B, Gordon SD, Holland C, Siviour CR, Vollrath F, Windmill JFC. 2014. The Speed of Sound in Silk: Linking Material Performance to Biological Function. Adv. Mater. 26:5179-5183.

by Shira | Jun 6, 2014 |

Whilst renowned for exceptional mechanical properties, [ 1 ] little is known about the sonic properties of silk. This is surprising given its widespread use by the spider for remote sensing and communication, as well as current industrial research efforts in the production of multifunctional materials. [ 2,3 ] To address this gap in our knowledge and provide further bioinspiration, this paper presents a systematic study confirming the physical basis of spider silk’s sonic properties through a unique combination of laser vibrometry and high-rate ballistic impact. We report that modification of silk’s modulus allows the spider to finely control the sonic properties: achieved either actively by spider spinning behavior or passively in response to the environment. Interpreting our results in the context of whole webs, we propose silk fi bers are “tuned” to a resonant frequency that can be accessed through spider “plucking” behavior, which enables them to locate both prey and structural damage. Through comparison to cocoon silk and other industrial fibers, we find that spider dragline silk has the largest wavespeed range of any known material, making it an ideal model for fabrication of adjustable, green multifunctional materials.   Mortimer B, Gordon SD, Holland C, Siviour CR, Vollrath F, Windmill JFC. 2014. The Speed of Sound in Silk: Linking Material Performance to Biological Function. Adv. Mater....

Gordon SD, Uetz GW. 2012. Environmental interference: impact of acoustic noise on seismic communication and mating success. Behavioral Ecology. 23:700-714.

by Shira | Mar 15, 2012 |

Sound is abundant in the environment, often creating ‘‘noise’’ that interferes with animal communication. Animals cope with acoustic interference in a variety of ways, including raising their signal volume (the Lombard effect), changing the pattern, frequency or duration of signals, or changing the time of day when signaling. Although many arthropods use substrate-borne vibration (seismic) signals, the effect of interference from (airborne) acoustic noise on their communication is not well studied. We tested the effects of 3 different types of airborne acoustic sounds on substrate-borne seismic communication and mating success of the ground-dwelling wolf spider, Schizocosa ocreata. We used band-limited white noise (0–4 kHz), predatory bird calls (northern cardinal Cardinalis cardinalis), and a cicada chorus (mixed Magicicada spp.) as interference stimuli. Spider behavior and mating success were differentially affected by each type of environmental acoustic sound. Males took longer to initiate courtship with bird calls, although white noise and cicada calls did not affect male signaling. Females oriented toward males more often with white noise but showed no change in their orientation behavior with bird or cicada calls. Finally, female receptivity and mating success were reduced with white noise and bird calls, whereas cicada calls had no effect. Our data suggest that wolf spiders using seismic vibration in communication respond differently to various types of airborne sounds, transmitted as vibrations, in their environment. This work is among the first to highlight how airborne sounds create seismic interference differentially affecting the behaviors of arthropods living in the leaf litter. Key words: behavioral plasticity, bioacoustics, bird song, cicada, communication, environment, interference, Schizocosa ocreata, sound, vibration, wolf spider. [Behav Ecol]   Gordon...