1
|
Zheng X, Kamat AM, Cao M, Triantafyllou MS, Kottapalli AGP. Wonders of Harbor and Grey Seal Whiskers: Morphology, Natural Frequencies, and 3D Modeling. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2025:e2500724. [PMID: 40305772 DOI: 10.1002/advs.202500724] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2025] [Revised: 03/31/2025] [Indexed: 05/02/2025]
Abstract
Seals can track fish using highly sensitive whiskers; however, the extent to which their morphologically diverse whiskers respond to hydrodynamic signals across frequencies remains unexplored. To address this, the lengths, thicknesses, curvatures, and natural frequencies of whisker arrays in grey seals (Halichoerus grypus) and harbor seals (Phoca vitulina) are measured. These values are mapped to their corresponding locations on the seal muzzle, and spatial trends (rostral-caudal and ventral-dorsal) are analyzed. These findings show that over 50% of whiskers exhibit underwater natural frequencies exceeding 80 Hz, which overlap with hydrodynamic fish trail frequencies (>100 Hz), demonstrating the adaptation of seal whiskers to hydrodynamic signals. Additionally, an open-access database of 141 full-length 3D whisker models is established. A streamlined method based on Euler spirals is proposed to fit and map seal whiskers simultaneously. This method evaluates the curvature of the full-length seal whisker and calculates morphological parameters (e.g., whisker axis and cross-sectional orientation angles) that are required for 3D whisker construction. The database of 3D seal whiskers offers a valuable resource for researchers in computational fluid dynamics, experimental biology, and sensor technology, supporting multidisciplinary studies of seal whiskers.
Collapse
Affiliation(s)
- Xingwen Zheng
- Engineering and Technology Institute Groningen, Faculty of Science and Engineering, University of Groningen, Groningen, 9747AG, Netherlands
- Institute of Cyber-Systems and Control, Department of Control Science and Engineering, Zhejiang University, Hangzhou, 310027, China
| | - Amar M Kamat
- Engineering and Technology Institute Groningen, Faculty of Science and Engineering, University of Groningen, Groningen, 9747AG, Netherlands
| | - Ming Cao
- Engineering and Technology Institute Groningen, Faculty of Science and Engineering, University of Groningen, Groningen, 9747AG, Netherlands
| | - Michael S Triantafyllou
- Department of Mechanical Engineering, Massachusetts Institute of Technology (MIT), Cambridge, MA, 02139, USA
- MIT Sea Grant College Program, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA, 02139, USA
| | - Ajay Giri Prakash Kottapalli
- Engineering and Technology Institute Groningen, Faculty of Science and Engineering, University of Groningen, Groningen, 9747AG, Netherlands
- MIT Sea Grant College Program, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA, 02139, USA
| |
Collapse
|
2
|
Efron B, Ntelezos A, Katz Y, Lampl I. Detection and neural encoding of whisker-generated sounds in mice. Curr Biol 2025; 35:1211-1226.e8. [PMID: 39978346 DOI: 10.1016/j.cub.2025.01.061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2024] [Revised: 01/07/2025] [Accepted: 01/28/2025] [Indexed: 02/22/2025]
Abstract
The vibrissa system of mice and other rodents enables active sensing via whisker movements and is traditionally considered a purely tactile system. Here, we ask whether whisking against objects produces audible sounds and whether mice are capable of perceiving these sounds. We found that whisking by head-fixed mice against objects produces audible sounds well within their hearing range. We recorded neural activity in the auditory cortex of mice in which we had abolished vibrissae tactile sensation and found that the firing rate of auditory neurons was strongly modulated by whisking against objects. Furthermore, the object's identity could be reliably decoded from the population's neuronal activity and closely matched the decoding patterns derived from sounds that were recorded simultaneously, suggesting that neuronal activity reflects acoustic information. Lastly, trained mice, in which vibrissae tactile sensation was abolished, were able to accurately identify objects solely based on the sounds produced during whisking. Our results suggest that, beyond its traditional role as a tactile sensory system, the vibrissa system of rodents engages both tactile and auditory modalities in a multimodal manner during active exploration.
Collapse
Affiliation(s)
- Ben Efron
- Department of Brain Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Athanasios Ntelezos
- Department of Brain Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Yonatan Katz
- Department of Brain Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Ilan Lampl
- Department of Brain Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel.
| |
Collapse
|
3
|
Kamat AM, Zheng X, Bos J, Cao M, Triantafyllou MS, Kottapalli AGP. Undulating Seal Whiskers Evolved Optimal Wavelength-to-Diameter Ratio for Efficient Reduction in Vortex-Induced Vibrations. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024; 11:e2304304. [PMID: 37847914 PMCID: PMC10787063 DOI: 10.1002/advs.202304304] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Revised: 09/08/2023] [Indexed: 10/19/2023]
Abstract
Seals are well-known for their remarkable hydrodynamic trail-following capabilities made possible by undulating flow-sensing whiskers that enable the seals to detect fish swimming as far as 180 m away. In this work, the form-function relationship in the undulating whiskers of two different phocid seal species, viz. harbor and gray seals, is studied. The geometry and material properties of excised harbor and grey seal whiskers are systematically characterized using blue light 3D scanning, optical and scanning electron microscopy, and nanoindentation. The effect of the undulating geometry on the whiskers' vibration in uniform water flow is studied using both experimental (piezoelectric MEMS and 3D-printed piezoresistive sensors developed in-house) and numerical (finite element method) techniques. The results indicate that the dimensionless ratio of undulation wavelength to mean whisker diameter (λ/Dm ) in phocid seals may have evolved to be in the optimal range of 4.4-4.6, enabling an order-of-magnitude reduction in vortex-induced vibrations (compared to a similarly-shaped circular cylinder) and, consequently, an enhanced flow sensing capability with minimal self-induced noise. The results highlight the importance of the dimensionless λ/Dm ratio in the biomimetic design of seal whisker-inspired vibration-resistant structures, such as marine risers and wake detection sensors for submarines.
Collapse
Affiliation(s)
- Amar M Kamat
- Bioinspired MEMS and Biomedical Devices, Engineering and Technology Institute Groningen, Faculty of Science and Engineering, University of Groningen, Groningen, 9747AG, The Netherlands
| | - Xingwen Zheng
- Bioinspired MEMS and Biomedical Devices, Engineering and Technology Institute Groningen, Faculty of Science and Engineering, University of Groningen, Groningen, 9747AG, The Netherlands
| | - Julian Bos
- Bioinspired MEMS and Biomedical Devices, Engineering and Technology Institute Groningen, Faculty of Science and Engineering, University of Groningen, Groningen, 9747AG, The Netherlands
| | - Ming Cao
- Discrete Technology and Production Automation Group, Engineering and Technology Institute Groningen, Faculty of Science and Engineering, University of Groningen, Groningen, 9747AG, The Netherlands
| | - Michael S Triantafyllou
- Department of Mechanical Engineering, Massachusetts Institute of Technology (MIT), Cambridge, MA, 02139, USA
- MIT Sea Grant College Program, Massachusetts Institute of Technology (MIT), Cambridge, MA, 02139, USA
| | - Ajay Giri Prakash Kottapalli
- Bioinspired MEMS and Biomedical Devices, Engineering and Technology Institute Groningen, Faculty of Science and Engineering, University of Groningen, Groningen, 9747AG, The Netherlands
- MIT Sea Grant College Program, Massachusetts Institute of Technology (MIT), Cambridge, MA, 02139, USA
| |
Collapse
|
4
|
Zheng X, Kamat AM, Cao M, Kottapalli AGP. Creating underwater vision through wavy whiskers: a review of the flow-sensing mechanisms and biomimetic potential of seal whiskers. J R Soc Interface 2021; 18:20210629. [PMID: 34699729 DOI: 10.1098/rsif.2021.0629] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Seals are known to use their highly sensitive whiskers to precisely follow the hydrodynamic trail left behind by prey. Studies estimate that a seal can track a herring that is swimming as far as 180 m away, indicating an incredible detection apparatus on a par with the echolocation system of dolphins and porpoises. This remarkable sensing capability is enabled by the unique undulating structural morphology of the whisker that suppresses vortex-induced vibrations (VIVs) and thus increases the signal-to-noise ratio of the flow-sensing whiskers. In other words, the whiskers vibrate minimally owing to the seal's swimming motion, eliminating most of the self-induced noise and making them ultrasensitive to the vortices in the wake of escaping prey. Because of this impressive ability, the seal whisker has attracted much attention in the scientific community, encompassing multiple fields of sensory biology, fluid mechanics, biomimetic flow sensing and soft robotics. This article presents a comprehensive review of the seal whisker literature, covering the behavioural experiments on real seals, VIV suppression capabilities enabled by the undulating geometry, wake vortex-sensing mechanisms, morphology and material properties and finally engineering applications inspired by the shape and functionality of seal whiskers. Promising directions for future research are proposed.
Collapse
Affiliation(s)
- Xingwen Zheng
- Engineering and Technology Institute Groningen, Faculty of Science and Engineering, University of Groningen, Nijenborgh 4, 9747AG Groningen, The Netherlands
| | - Amar M Kamat
- Engineering and Technology Institute Groningen, Faculty of Science and Engineering, University of Groningen, Nijenborgh 4, 9747AG Groningen, The Netherlands
| | - Ming Cao
- Engineering and Technology Institute Groningen, Faculty of Science and Engineering, University of Groningen, Nijenborgh 4, 9747AG Groningen, The Netherlands
| | - Ajay Giri Prakash Kottapalli
- Engineering and Technology Institute Groningen, Faculty of Science and Engineering, University of Groningen, Nijenborgh 4, 9747AG Groningen, The Netherlands.,MIT Sea Grant College Program, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
| |
Collapse
|
5
|
Jiang Y, Zhao P, Ma Z, Shen D, Liu G, Zhang D. Enhanced flow sensing with interfacial microstructures. BIOSURFACE AND BIOTRIBOLOGY 2020. [DOI: 10.1049/bsbt.2019.0043] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Affiliation(s)
- Yonggang Jiang
- Institute of Bionic and Micro‐Nano SystemsSchool of Mechanical Engineering and AutomationBeihang UniversityBeijing100191People's Republic of China
- International Research Institute of Multidisciplinary ScienceBeihang UniversityBeijing100191People's Republic of China
| | - Peng Zhao
- Institute of Bionic and Micro‐Nano SystemsSchool of Mechanical Engineering and AutomationBeihang UniversityBeijing100191People's Republic of China
| | - Zhiqiang Ma
- Institute of Bionic and Micro‐Nano SystemsSchool of Mechanical Engineering and AutomationBeihang UniversityBeijing100191People's Republic of China
| | - Dawei Shen
- Institute of Bionic and Micro‐Nano SystemsSchool of Mechanical Engineering and AutomationBeihang UniversityBeijing100191People's Republic of China
| | - Gongchao Liu
- Institute of Bionic and Micro‐Nano SystemsSchool of Mechanical Engineering and AutomationBeihang UniversityBeijing100191People's Republic of China
| | - Deyuan Zhang
- Institute of Bionic and Micro‐Nano SystemsSchool of Mechanical Engineering and AutomationBeihang UniversityBeijing100191People's Republic of China
| |
Collapse
|
6
|
Kane SA, Van Beveren D, Dakin R. Biomechanics of the peafowl's crest reveals frequencies tuned to social displays. PLoS One 2018; 13:e0207247. [PMID: 30485316 PMCID: PMC6261573 DOI: 10.1371/journal.pone.0207247] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Accepted: 10/26/2018] [Indexed: 11/18/2022] Open
Abstract
Feathers act as vibrotactile sensors that can detect mechanical stimuli during avian flight and tactile navigation, suggesting that they may also detect stimuli during social displays. In this study, we present the first measurements of the biomechanical properties of the feather crests found on the heads of birds, with an emphasis on those from the Indian peafowl (Pavo cristatus). We show that in peafowl these crest feathers are coupled to filoplumes, small feathers known to function as mechanosensors. We also determined that airborne stimuli with the frequencies used during peafowl courtship and social displays couple efficiently via resonance to the vibrational response of their feather crests. Specifically, vibrational measurements showed that although different types of feathers have a wide range of fundamental resonant frequencies, peafowl crests are driven near-optimally by the shaking frequencies used by peacocks performing train-rattling displays. Peafowl crests were also driven to vibrate near resonance in a playback experiment that mimicked the effect of these mechanical sounds in the acoustic very near-field, reproducing the way peafowl displays are experienced at distances ≤ 1.5m in vivo. When peacock wing-shaking courtship behaviour was simulated in the laboratory, the resulting airflow excited measurable vibrations of crest feathers. These results demonstrate that peafowl crests have mechanical properties that allow them to respond to airborne stimuli at the frequencies typical of this species' social displays. This suggests a new hypothesis that mechanosensory stimuli could complement acoustic and visual perception and/or proprioception of social displays in peafowl and other bird species. We suggest behavioral studies to explore these ideas and their functional implications.
Collapse
Affiliation(s)
- Suzanne Amador Kane
- Physics Department, Haverford College, Haverford, PA United States of America
| | - Daniel Van Beveren
- Physics Department, Haverford College, Haverford, PA United States of America
| | - Roslyn Dakin
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada
- Migratory Bird Center, Smithsonian Conservation Biology Institute, Washington, DC, United States of America
| |
Collapse
|
7
|
Rothschild BM, Naples V. Apparent sixth sense in theropod evolution: The making of a Cretaceous weathervane. PLoS One 2017; 12:e0187064. [PMID: 29095949 PMCID: PMC5667833 DOI: 10.1371/journal.pone.0187064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Accepted: 10/12/2017] [Indexed: 11/17/2022] Open
Abstract
Objective Two separate and distinctive skills are necessary to find prey: Detection of its presence and determination of its location. Surface microscopy of the dentary of albertosaurines revealed a previously undescribed sensory modification, as will be described here. While dentary “foramina” were previously thought to contain tactile sensory organs, the potential function of this theropod modification as a unique localizing system is explored in this study. Method Dentary surface perforations were examined by surface epi-illumination microscopy in tyrannosaurine and albertosaurine dinosaurs to characterize their anatomy. Fish lateral lines were examined as potentially comparable structures. Result In contrast to the subsurface vascular bifurcation noted in tyrannosaurines (which lack a lateral dentary surface groove), the area subjacent to the apertures in albertosaurine grooves has the appearance of an expanded chamber. That appearance seemed to be indistinguishable from the lateral line of fish. Conclusion Dentary groove apertures in certain tyrannosaurid lines (specifically albertosaurines) not only have a unique appearance, but one with significant functional and behavior implications. The appearance of the perforations in the dentary groove of albertosaurines mirrors that previously noted only with specialized neurologic structures accommodating derived sensory functions, as seen in the lateral line of fish. The possibility that this specialized morphology could also represent a unique function in albertosaurine theropods for interacting with the environment or facilitating prey acquisition cannot be ignored. It is suggested that these expanded chambers function in perceiving and aligning the body relative to the direction of wind, perhaps a Cretaceous analogue of the contemporary midwestern weathervane.
Collapse
Affiliation(s)
- Bruce M Rothschild
- West Virginia University College of Medicine, Department of Medicine, Morgantown, West Virginia United States of America.,Carnegie Museum, Pittsburgh, Pennsylvania, United States of America
| | - Virginia Naples
- Northern Illinois University, DeKalb, Illinois, United States of America
| |
Collapse
|
8
|
Ginter Summarell CC, Ingole S, Fish FE, Marshall CD. Comparative Analysis of the Flexural Stiffness of Pinniped Vibrissae. PLoS One 2015; 10:e0127941. [PMID: 26132102 PMCID: PMC4489197 DOI: 10.1371/journal.pone.0127941] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Accepted: 04/21/2015] [Indexed: 11/18/2022] Open
Abstract
Vibrissae are important components of the mammalian tactile sensory system and are used to detect vibrotactile stimuli in the environment. Pinnipeds have the largest and most highly innervated vibrissae among mammals, and the hair shafts function as a biomechanical filter spanning the environmental stimuli and the neural mechanoreceptors deep in the follicle-sinus complex. Therefore, the material properties of these structures are critical in transferring vibrotactile information to the peripheral nervous system. Vibrissae were tested as cantilever beams and their flexural stiffness (EI) was measured to test the hypotheses that the shape of beaded vibrissae reduces EI and that vibrissae are anisotropic. EI was measured at two locations on each vibrissa, 25% and 50% of the overall length, and at two orientations to the point force. EI differed in orientations that were normal to each other, indicating a functional anisotropy. Since vibrissae taper from base to tip, the second moment of area (I) was lower at 50% than 25% of total length. The anterior orientation exhibited greater EI values at both locations compared to the dorsal orientation for all species. Smooth vibrissae were generally stiffer than beaded vibrissae. The profiles of beaded vibrissae are known to decrease the amplitude of vibrations when protruded into a flow field. The lower EI values of beaded vibrissae, along with the reduced vibrations, may function to enhance the sensitivity of mechanoreceptors to detection of small changes in flow from swimming prey by increasing the signal to noise ratio. This study builds upon previous morphological and hydrodynamic analyses of vibrissae and is the first comparative study of the mechanical properties of pinniped vibrissae.
Collapse
Affiliation(s)
- Carly C. Ginter Summarell
- Department of Wildlife and Fisheries Sciences, Texas A&M University, College Station, Texas, 77843, United States of America
| | - Sudeep Ingole
- Department of Marine Engineering Technology, Texas A&M University, Galveston, Texas, 77553, United States of America
| | - Frank E. Fish
- Department of Biology, West Chester University, West Chester, Pennsylvania, 19383, United States of America
| | - Christopher D. Marshall
- Department of Wildlife and Fisheries Sciences, Texas A&M University, College Station, Texas, 77843, United States of America
- Department of Marine Biology, Texas A&M University, Galveston, Texas, 77553, United States of America
| |
Collapse
|
9
|
Murphy CT, Eberhardt WC, Calhoun BH, Mann KA, Mann DA. Effect of angle on flow-induced vibrations of pinniped vibrissae. PLoS One 2013; 8:e69872. [PMID: 23922834 PMCID: PMC3724740 DOI: 10.1371/journal.pone.0069872] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2013] [Accepted: 06/12/2013] [Indexed: 11/26/2022] Open
Abstract
Two types of vibrissal surface structures, undulated and smooth, exist among pinnipeds. Most Phocidae have vibrissae with undulated surfaces, while Otariidae, Odobenidae, and a few phocid species possess vibrissae with smooth surfaces. Variations in cross-sectional profile and orientation of the vibrissae also exist between pinniped species. These factors may influence the way that the vibrissae behave when exposed to water flow. This study investigated the effect that vibrissal surface structure and orientation have on flow-induced vibrations of pinniped vibrissae. Laser vibrometry was used to record vibrations along the whisker shaft from the undulated vibrissae of harbor seals (Phoca vitulina) and northern elephant seals (Mirounga angustirostris) and the smooth vibrissae of California sea lions (Zalophus californianus). Vibrations along the whisker shaft were measured in a flume tank, at three orientations (0°, 45°, 90°) to the water flow. The results show that vibration frequency and velocity ranges were similar for both undulated and smooth vibrissae. Angle of orientation, rather than surface structure, had the greatest effect on flow-induced vibrations. Vibration velocity was up to 60 times higher when the wide, flat aspect of the whisker faced into the flow (90°), compared to when the thin edge faced into the flow (0°). Vibration frequency was also dependent on angle of orientation. Peak frequencies were measured up to 270 Hz and were highest at the 0° orientation for all whiskers. Furthermore, CT scanning was used to quantify the three-dimensional structure of pinniped vibrissae that may influence flow interactions. The CT data provide evidence that all vibrissae are flattened in cross-section to some extent and that differences exist in the orientation of this profile with respect to the major curvature of the hair shaft. These data support the hypothesis that a compressed cross-sectional profile may play a key role in reducing self-noise of the vibrissae.
Collapse
Affiliation(s)
- Christin T Murphy
- College of Marine Science, University of South Florida, St Petersburg, Florida, United States of America.
| | | | | | | | | |
Collapse
|