Vibrissal touch sensing in the harbor seal (Phoca vitulina): how do seals judge size?

@article{Grant2013VibrissalTS,
  title={Vibrissal touch sensing in the harbor seal (Phoca vitulina): how do seals judge size?},
  author={Robyn A. Grant and Sven Wieskotten and Nina Wengst and Tony J. Prescott and Guido Dehnhardt},
  journal={Journal of Comparative Physiology A},
  year={2013},
  volume={199},
  pages={521-533}
}
Abstract“Whisker specialists” such as rats, shrews, and seals actively employ their whiskers to explore their environments and extract object properties such as size, shape, and texture. It has been suggested that whiskers could be used to discriminate between different sized objects in one of two ways: (i) to use whisker positions, such as angular position, spread or amplitude to approximate size; or (ii) to calculate the number of whiskers that contact an object. This study describes in… 
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TLDR
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TLDR
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References

SHOWING 1-10 OF 41 REFERENCES
Sensitivity of the mystacial vibrissae of harbour seals (Phoca vitulina) for size differences of actively touched objects.
TLDR
The Weber fractions obtained for the larger standard discs indicate that harbour seals can use their mystacial vibrissae as efficiently for active touch as monkeys use their hands.
The role of orienting in vibrissal touch sensing
TLDR
Data suggest that orienting to tactile cues, detected by the vibrissal system, plays a crucial role throughout the life of a rat.
Active vibrissal sensing in rodents and marsupials
TLDR
It is proposed that the presence of active vibrissal touch in both rodents and marsupials suggests that this behavioural capacity emerged at an early stage in the evolution of therian mammals.
Diving in darkness: whiskers as sense organs of the ringed seal (Phoca hispida saimensis)
TLDR
Underwater vocalization and the functional structure of different vibrissae of the ringed seal of Lake Saimaa, Eastern Finland, were studied and it is suggested that echolocation is used in orientation and feeding.
Ambient temperature does not affect the tactile sensitivity of mystacial vibrissae in harbour seals.
TLDR
The thermographic examination revealed that the skin areas of the head where the mystacial and supraorbital vibrissae are located show a substantially higher degree of thermal emission than do adjacent skin areas, suggesting that, in the vibrissal follicles of harbour seals, no vasoconstriction occurs during cold acclimation, so that the appropriate operating temperature for the mechanoreceptors is maintained.
Tactile size discrimination by a California sea lion (Zalophus californianus) using its mystacial vibrissae
TLDR
The capability of a blindfolded California sea lion to discriminate diameter differences of circular discs by means of active touch with its mystacial vibrissae was studied, suggesting that the accuracy of the sea lion's size discrimination was determined by the efficiency of two sensory systems: the mechanosensitivity of follicle receptors as well as kinaesthesis.
Afferent fibers from mystacial vibrissae of cats and seals.
  • R. Dykes
  • Biology
    Journal of neurophysiology
  • 1975
TLDR
It is postulated that vibrissae provide fine textural information about surfaces, and the range of thresholds in the RA fiber group within each follicle represents a mechanism of encoding the intensity of vibratory stimuli.
Active touch sensing in the rat: anticipatory and regulatory control of whisker movements during surface exploration.
TLDR
High-speed video analysis is used to investigate whisker movements in untrained, freely moving rats encountering unexpected, vertical surfaces to support two hypotheses: 1) that the relative velocities of different whiskers may be actively controlled by the rat and 2) that control of whisker velocity and timing may serve to increase the number and duration of whisking-surface contacts while ensuring that such contacts are made with a light touch.
Haptic Object Localization in the Vibrissal System: Behavior and Performance
TLDR
It is concluded that horizontal object localization in the rat vibrissal system can reach hyperacuity level and is an active sensing process: whisker movements are both required and beneficiary, in a graded manner, for making accurate positional judgments.
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