Distance estimation

- current project - 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.

On the video, seal Nick is performing in the distance estimation experiment. He leaves its station on command 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.

Thermoregulation

In cold waters the seals are facing the problem of loosing too much body heat due to the increased thermal conductivity of water. Therefore seals have developed isolation mechanisms to prevent heat loss. However, on land the seals are faced with the opposite problem of getting rid of excessive heat. Our research revealed that phocid seals can dissipate heat via thermal windows which are well-vascularized areas on the body (Mauck, Eysel & Dehnhardt 2003). In this project we examined the development of thermal windows in detail. Furthermore thermoregulatory aspects of fur seals are investigated for comparison.

On the video which was filmed with the help of an infrared thermo-camera the development of thermal windows on the body of harbour seals close to the back flippers can be observed. The temperature on the video is colour-coded with blue referring to low temperatures down to 18°C and red referring to high temperatures up to maximal 38°C.