Harbour seals (Phoca vitulina) are able to time precisely
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Time along with space is one of the two fundamental dimensions of life. Whereas spatial aspects have been considered in experiments with marine mammals, research has so far not focused on timing per se although it is most likely involved in many behaviours such as foraging or navigation. This study investigated whether harbour seals possess a sense of time and how precisely they are able to discriminate time intervals. Experiments took place in a chamber that allowed keeping ambient illumination constant at 40 lx. The animal was presented with a white circle on a black background on a monitor displayed for a preset time interval. In a two-alternative forced-choice experiment, the animal had to indicate the presence of the standard or a longer comparison time interval by moving its head to one out of two response targets. Time difference thresholds were assessed for various standard intervals between 3 to 30 s adopting a staircase procedure. The experimental animal found access to the task easily and discriminated time intervals with difference thresholds partly in the millisecond range. Thus our study revealed a well-developed sense of time in a pinniped species. Time, besides information provided by the classical senses, is thus most likely an important parameter seals can rely on for various tasks including navigation and foraging.
KeywordsTiming Interval timing Pinnipeds Sense of time Time difference thresholds
The authors would like to express their sincere thanks to Lars Miersch for technical assistance and to all colleagues at the Marine Science Center for ideas and support.
This study was supported by a grant of the VolkswagenStiftung to GD and a grant of the Landesgraduiertenfoerderung Mecklenburg-Vorpommern to TH.
Complaince with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
The experiments were carried out in accordance with the European Communities Council Directive of November 24, 1986 (86/609/EEC). According to § 8 of the German Animal Welfare Act of May 18, 2006 (BGB I. I S. 1206, 1313), experiments conducted in this study were not subject to approval or notification, since they did not cause pain, suffering or injuries to the animals.
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