Navigating seals perform a star turn
SEALS in the open ocean may be able to navigate by the stars.
Whales, sea lions and seals exhibit a behaviour called spyhopping, where they stick their heads out of the water, apparently surveying their surroundings. This led some biologists to suspect that these mammals might use the stars for navigation.
Björn Mauck of the University of Southern Denmark in Odense and colleagues used a specially built pool planetarium to test two harbour seals on their ability to recognise and orient themselves by the stars. The 5-metre round pool was covered by a dome onto which was projected a simulation of the northern sky, with about 6000 stars.
The team highlighted a particular star with a laser pointer, rewarding the seals for swimming towards it. They found that even when the whole sky was rotated at random, the seals could still home in on the star with very high accuracy (Animal Cognition, DOI: 10.1007/s10071-008-0156-1).
"Seals and many other animals are exposed to the starry sky every clear night, and thus certainly have sufficient opportunities to learn the patterns of stars," says Mauck.
The seals' technique appears to be similar to that of Polynesian sailors, who traditionally linked stars to spots on the horizon where they rise.