Hydrodynamic Perception in Pinnipeds

Hanke, Wolf; Wieskotten, Sven; Niesterok, Benedikt; Miersch, Lars; Witte, Matthias; Brede, M.; Leder, Alfred; Dehnhardt, Guido

doi:10.1007/978-3-642-28302-4_16

Cited by 10 publications

(10 citation statements)

References 22 publications

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“…Although NES have enhanced visual sensitivity (Levenson et al, ), vision may be limited because they forage on vertically migrating prey (Hassrick et al, ; Kuhn et al, ) at depths greater than 500 m during the day and at night where light levels are negligible (Le Boeuf et al, ; Le Boeuf et al, ). Harbor seals ( Phoca vitulina ) and California sea lions ( Zalophus californianus ) have been shown to detect and follow hydrodynamic trails using their vibrissae alone (Dehnhardt et al, ; Schulte‐Pelkum et al, ; Gläser et al, ), which are sensitive to changes in water velocity (Renouf, ; Dehnhardt et al, ; Hanke et al, ). Hydrodynamic trails left behind by swimming prey can persist for several minutes and have particle velocities within the detection range of the vibrissae (Hanke et al, ; Dehnhardt et al, ; Hanke and Bleckmann, ; Fish and Lauder, ).…”

Section: Introductionmentioning

confidence: 99%

Are Vibrissae Viable Sensory Structures for Prey Capture in Northern Elephant Seals, Mirounga angustirostris?

McGovern

Marshall

Davis

2014

The Anatomical Record

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Little is known about the tactics northern elephant seals (NES) use to capture prey due to the difficulties in observing these animals underwater. NES forage on vertically migrating prey at depths >500 m during day and at night where light levels are negligible. Although NES have increased visual sensitivity in deep water, vision is likely a limited sensory modality. Still images of NES foraging show that the mystacial vibrissae are protracted before prey capture. As a representative phocid, harbor seals can follow hydrodynamic trails using their vibrissae, and are highly sensitive to water velocity changes. In lieu of performance data, vibrissal innervation can be used as a proxy for sensitivity. Although comparative data are few, seals average 1,000 to 1,600 axons per vibrissa (five to eight times more than terrestrial mammals). To test the hypothesis that NES have increased innervation as other pinnipeds, vibrissae from the ventral-caudal mystacial field from nine individuals were sectioned and stained for microstructure (trichrome) and innervation (Bodian silver stain). Follicles were tripartite and consisted of lower and upper cavernous sinuses separated by a ring sinus containing an asymmetrical ringwulst. The deep vibrissal nerve penetrated the follicular capsule at the base, branched into several bundles, and coursed through the lower cavernous sinus to the ring sinus. Axons in the ring sinus terminated in the ringwulst and along the inner conical body. NES averaged 1,584 axons per vibrissa. The results add to the growing body of evidence that phocids, and perhaps all pinnipeds, possess highly sensitive mystacial vibrissae that detect prey. Anat Rec, 298:750-760, 2015. V C 2014 Wiley Periodicals, Inc.

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Section: Introductionmentioning

confidence: 99%

Are Vibrissae Viable Sensory Structures for Prey Capture in Northern Elephant Seals, Mirounga angustirostris?

McGovern

Marshall

Davis

2014

The Anatomical Record

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“…Pinnipeds use their vibrissae for the tactile discrimination of surfaces (Dehnhardt, 1994;Dehnhardt and Kaminski, 1995;Grant et al, 2013) and the detection and following of underwater wakes (Dehnhardt et al, 2001;Gläser et al, 2011). Although behavioral and histological evidence suggests that the vibrissal system in pinnipeds is adapted to extract complex tactile information from the environment (Dehnhardt et al, 2014(Dehnhardt et al, , 1998(Dehnhardt et al, , 2001Dehnhardt and Kaminski, 1995;Hanke et al, 2012;Wieskotten et al, 2010Wieskotten et al, , 2011, the sensitivity of this sensory modality is not fully understood. A few studies have utilized different methods to directly measure the tactile sensitivity of seals to a range of stimulus frequencies.…”

Section: Introductionmentioning

confidence: 99%

Vibrissal sensitivity in a harbor seal (Phoca vitulina)

Murphy

Reichmuth

Mann

2015

Journal of Experimental Biology

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Prior efforts to characterize the capabilities of the vibrissal system in seals have yielded conflicting results. Here, we measured the sensitivity of the vibrissal system of a harbor seal (Phoca vitulina) to directly coupled sinusoidal stimuli delivered by a vibrating plate. A trained seal was tested in a psychophysical paradigm to determine the smallest velocity that was detectable at nine frequencies ranging from 10 to 1000 Hz. The stimulus plate was driven by a vibration shaker and the velocity of the plate at each frequency-amplitude combination was calibrated with a laser vibrometer. To prevent cueing from other sensory stimuli, the seal was fitted with a blindfold and headphones playing broadband masking noise. The seal was sensitive to vibrations across the range of frequencies tested, with best sensitivity of 0.09 mm s −1 at 80 Hz. Velocity thresholds as a function of frequency showed a characteristic U-shaped curve with decreasing sensitivity below 20 Hz and above 250 Hz. To ground-truth the experimental setup, four human subjects were tested in the same paradigm using their thumb to contact the vibrating plate. Threshold measurements for the humans were similar to those of the seal, demonstrating comparable tactile sensitivity for their structurally different mechanoreceptive systems. The thresholds measured for the harbor seal in this study were about 100 times more sensitive than previous in-air measures of vibrissal sensitivity for this species. The results were similar to those reported by others for the detection of waterborne vibrations, but show an extended range of frequency sensitivity.

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“…Larger fishes receive a poorer signal quality owing to turbulence, and for this reason some larger sharks are known not to use lateral lines for prey detection [65]. Some marine mammals (seals and sea lions) have the ability to follow turbulent trails using their mystacial vibrissae [66], probably owing to being larger than the integral length scale set by the target. The camera eye takes records for both the smallest and the largest eye: the smallest image-forming eyes (and body sizes) are found in the fish Schindleria brevipinguis (L % 7 mm [67]), and the pygmy squids (L % 1.5 mm [58]), which compares well with our predicted size limit.…”

Section: Discussionmentioning

confidence: 99%

Size structures sensory hierarchy in ocean life

et al. 2015

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Survival in aquatic environments requires organisms to have effective means of collecting information from their surroundings through various sensing strategies. In this study, we explore how sensing mode and range depend on body size. We find a hierarchy of sensing modes determined by body size. With increasing body size, a larger battery of modes becomes available (chemosensing, mechanosensing, vision, hearing and echolocation, in that order) while the sensing range also increases. This size-dependent hierarchy and the transitions between primary sensory modes are explained on the grounds of limiting factors set by physiology and the physical laws governing signal generation, transmission and reception. We theoretically predict the body size limits for various sensory modes, which align well with size ranges found in literature. The treatise of all ocean life, from unicellular organisms to whales, demonstrates how body size determines available sensing modes, and thereby acts as a major structuring factor of aquatic life.

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Hydrodynamic Perception in Pinnipeds

Cited by 10 publications

References 22 publications

Are Vibrissae Viable Sensory Structures for Prey Capture in Northern Elephant Seals, Mirounga angustirostris?

Are Vibrissae Viable Sensory Structures for Prey Capture in Northern Elephant Seals, Mirounga angustirostris?

Vibrissal sensitivity in a harbor seal (Phoca vitulina)

Size structures sensory hierarchy in ocean life

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