Sense of time

Time is, beside space, one of the fundamentals of every existence. Time is crucial for almost any activity including the day-night cycle, foraging, decision making or the control of vocalizations. Timing abilities have been demonstrated in many animal species - now including two pinniped species. A harbor seal and a fur seal were able to discriminate time intervals precisely. Thus besides information provided by other senses, harbor seals can also rely on time for foraging or orientation.

The video shows seal Luca in a timing experiment conducted in a dark chamber. His task was to indicate the shorter (standard) stimulus by moving its snout to the left and the longer (comparison) stimulus by movng its snout to the right. In this example, time intervals were marked by an optical stimulus presented for a specific time interval on the monitor. The standard stimulus is 800ms long, the comparison stimulus is 1100ms long. By decreasing the duration of the comparison interval, a difference threshold can be obtained.

Distance estimation

A crucial parameter that seals need to document for successful orientation is distance. In a first experiment on distance estimation, a harbor seal showed that it could estimate and reproduce at least one distance.

In the video seal Nick is performing in the distance estimation experiment. He leaves his station on command and encounters a first target on the water surface which marks the beginning of the sample distance interval. The second target marks the end of the sample distance interval. Upon passing this target the animal's task is to reproduce the sample distance interval. Its accuracy of reproduction is evaluated at the endpoint.

Detection of the magnetic field of the earth

When offshore, harbour seals cannot rely on numerous information channels for orientation. However, magnetic fields could provide orientation information on a small and large scale.

In a first experimental approach the ability of harbour seals to detect magnetic fields was analysed by means of two coils installed on the bottom of the seals' enclosure. A seal was required to swim towards the coils from a distance of approximately 15m. In each trial only one coil generated a magnetic field which the seal had to touch with its snout. On this video the seal is choosing correctly and returns to the experimenter at the water surface.