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Lancet dynamics in greater horseshoe bats, Rhinolophus ferrumequinum.

He W, Pedersen SC, Gupta AK, Simmons JA, Müller R - PLoS ONE (2015)

Bottom Line: Echolocating greater horseshoe bats (Rhinolophus ferrumequinum) emit their biosonar pulses nasally, through nostrils surrounded by fleshy appendages ('noseleaves') that diffract the outgoing ultrasonic waves.The broadcast beam shapes were found to be altered substantially by the observed small lancet movements.These findings demonstrate that-in addition to the previously described motions of the anterior leaf and the pinna-horseshoe bat biosonar has a third degree of freedom for fast changes that can happen on the time scale of the emitted pulses or the returning echoes and could provide a dynamic mechanism for the encoding of sensory information.

View Article: PubMed Central - PubMed

Affiliation: SDU-VT International Laboratory, School of Physics, Shandong University, Jinan, Shandong, China.

ABSTRACT
Echolocating greater horseshoe bats (Rhinolophus ferrumequinum) emit their biosonar pulses nasally, through nostrils surrounded by fleshy appendages ('noseleaves') that diffract the outgoing ultrasonic waves. Movements of one noseleaf part, the lancet, were measured in live bats using two synchronized high speed video cameras with 3D stereo reconstruction, and synchronized with pulse emissions recorded by an ultrasonic microphone. During individual broadcasts, the lancet briefly flicks forward (flexion) and is then restored to its original position. This forward motion lasts tens of milliseconds and increases the curvature of the affected noseleaf surfaces. Approximately 90% of the maximum displacements occurred within the duration of individual pulses, with 70% occurring towards the end. Similar lancet motions were not observed between individual pulses in a sequence of broadcasts. Velocities of the lancet motion were too small to induce Doppler shifts of a biologically-meaningful magnitude, but the maximum displacements were significant in comparison with the overall size of the lancet and the ultrasonic wavelengths. Three finite element models were made from micro-CT scans of the noseleaf post mortem to investigate the acoustic effects of lancet displacement. The broadcast beam shapes were found to be altered substantially by the observed small lancet movements. These findings demonstrate that-in addition to the previously described motions of the anterior leaf and the pinna-horseshoe bat biosonar has a third degree of freedom for fast changes that can happen on the time scale of the emitted pulses or the returning echoes and could provide a dynamic mechanism for the encoding of sensory information.

No MeSH data available.


Related in: MedlinePlus

Deflection pattern of the lancet.Four sequential frames (a, b, c, d) from a high-speed video recording of lancet movement (upper panel i) and the corresponding digital shape models (a′, b′, c′, d′; lower panel ii). These data (from male 1) depict a representative example of the lancet motion that was observed in all individual bats studied here. In each case, a, a′ are in the resting (upright) position, b, b′ are flexed forward 4°, c, c′ are flexed forward 8°, and d, d′ are maximally flexed at 12°.
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pone.0121700.g001: Deflection pattern of the lancet.Four sequential frames (a, b, c, d) from a high-speed video recording of lancet movement (upper panel i) and the corresponding digital shape models (a′, b′, c′, d′; lower panel ii). These data (from male 1) depict a representative example of the lancet motion that was observed in all individual bats studied here. In each case, a, a′ are in the resting (upright) position, b, b′ are flexed forward 4°, c, c′ are flexed forward 8°, and d, d′ are maximally flexed at 12°.

Mentions: Quantitative measurement of the lancet’s motion was implemented with synchronized recording using two high speed video cameras and an ultrasonic recording system with its microphone at a distance of 15 cm from the bat’s nostrils. Three landmarks were selected on the noseleaf (lancet tip, sella tip, and sella base, see Fig. 1i) and used to obtain the relative motion of lancet by stereo triangulation. By tracing the motion of lancet over time, the relationship between lancet motion and sonar pulse occurrence was determined for 27 out of 46 recorded biosonar sequences (13 sequences had no conspicuous lancet deformation, 6 showed some motions but the recordings had insufficient quality for three-dimensional tracking) which were subjected to statistical analysis (see Fig. 2 for an example, Table 1 for a summary of the statistics).


Lancet dynamics in greater horseshoe bats, Rhinolophus ferrumequinum.

He W, Pedersen SC, Gupta AK, Simmons JA, Müller R - PLoS ONE (2015)

Deflection pattern of the lancet.Four sequential frames (a, b, c, d) from a high-speed video recording of lancet movement (upper panel i) and the corresponding digital shape models (a′, b′, c′, d′; lower panel ii). These data (from male 1) depict a representative example of the lancet motion that was observed in all individual bats studied here. In each case, a, a′ are in the resting (upright) position, b, b′ are flexed forward 4°, c, c′ are flexed forward 8°, and d, d′ are maximally flexed at 12°.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4390203&req=5

pone.0121700.g001: Deflection pattern of the lancet.Four sequential frames (a, b, c, d) from a high-speed video recording of lancet movement (upper panel i) and the corresponding digital shape models (a′, b′, c′, d′; lower panel ii). These data (from male 1) depict a representative example of the lancet motion that was observed in all individual bats studied here. In each case, a, a′ are in the resting (upright) position, b, b′ are flexed forward 4°, c, c′ are flexed forward 8°, and d, d′ are maximally flexed at 12°.
Mentions: Quantitative measurement of the lancet’s motion was implemented with synchronized recording using two high speed video cameras and an ultrasonic recording system with its microphone at a distance of 15 cm from the bat’s nostrils. Three landmarks were selected on the noseleaf (lancet tip, sella tip, and sella base, see Fig. 1i) and used to obtain the relative motion of lancet by stereo triangulation. By tracing the motion of lancet over time, the relationship between lancet motion and sonar pulse occurrence was determined for 27 out of 46 recorded biosonar sequences (13 sequences had no conspicuous lancet deformation, 6 showed some motions but the recordings had insufficient quality for three-dimensional tracking) which were subjected to statistical analysis (see Fig. 2 for an example, Table 1 for a summary of the statistics).

Bottom Line: Echolocating greater horseshoe bats (Rhinolophus ferrumequinum) emit their biosonar pulses nasally, through nostrils surrounded by fleshy appendages ('noseleaves') that diffract the outgoing ultrasonic waves.The broadcast beam shapes were found to be altered substantially by the observed small lancet movements.These findings demonstrate that-in addition to the previously described motions of the anterior leaf and the pinna-horseshoe bat biosonar has a third degree of freedom for fast changes that can happen on the time scale of the emitted pulses or the returning echoes and could provide a dynamic mechanism for the encoding of sensory information.

View Article: PubMed Central - PubMed

Affiliation: SDU-VT International Laboratory, School of Physics, Shandong University, Jinan, Shandong, China.

ABSTRACT
Echolocating greater horseshoe bats (Rhinolophus ferrumequinum) emit their biosonar pulses nasally, through nostrils surrounded by fleshy appendages ('noseleaves') that diffract the outgoing ultrasonic waves. Movements of one noseleaf part, the lancet, were measured in live bats using two synchronized high speed video cameras with 3D stereo reconstruction, and synchronized with pulse emissions recorded by an ultrasonic microphone. During individual broadcasts, the lancet briefly flicks forward (flexion) and is then restored to its original position. This forward motion lasts tens of milliseconds and increases the curvature of the affected noseleaf surfaces. Approximately 90% of the maximum displacements occurred within the duration of individual pulses, with 70% occurring towards the end. Similar lancet motions were not observed between individual pulses in a sequence of broadcasts. Velocities of the lancet motion were too small to induce Doppler shifts of a biologically-meaningful magnitude, but the maximum displacements were significant in comparison with the overall size of the lancet and the ultrasonic wavelengths. Three finite element models were made from micro-CT scans of the noseleaf post mortem to investigate the acoustic effects of lancet displacement. The broadcast beam shapes were found to be altered substantially by the observed small lancet movements. These findings demonstrate that-in addition to the previously described motions of the anterior leaf and the pinna-horseshoe bat biosonar has a third degree of freedom for fast changes that can happen on the time scale of the emitted pulses or the returning echoes and could provide a dynamic mechanism for the encoding of sensory information.

No MeSH data available.


Related in: MedlinePlus