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Nick, a harbor seal, delved into the annals of the history of astronomy when Guido Dehnhardt, now a marine biologist at the University of Rostock, was studying how cetaceans orient themselves. Dr. Dehnhardt and colleague Björn Mauck suggested that if seals can distinguish stars, this may help explain how animals are able to complete long swims in otherwise featureless seas.
To test a seal’s astronomical skills, Dr. Mauck designed two of the widest-eyed, marvelous experiments in scientific history.
First, the team built the seal-o-scope, a lensless tube, and gave Nick a tour of the night sky. He constantly pressed his paddle when bright spots such as Venus, Sirius, and Polaris appeared; couldn’t see as many faint stars as humans could, researchers determined, but many possible celestial landmarks still existed for him.
Then Dr. Mauck did something even bigger. This time, two seals are invited to join, Nick and his smarter brother Malte.
Back in the pool at a Cologne zoo, the seals entered a 15-foot diameter dome, the edge of which rested on a floating ring. The interior of this bespoke aqua-planetarium is illuminated by 6,000 simulated stars. Dr. “They immediately swam past the planetarium and said to the stars, ‘Oh, what’s that?’ They looked like,” he said. “You get the impression that they really understand what that is.”
First, the researchers used a laser pointer to guide the seals to where the rim of the dome meets the water closest to Sirius, the Dog Star. If a seal swam and touched that part of the dome with its nose, it would get some fish. Then the cursor aimed directly at Sirius. Again, the seal’s task was to swim towards the star and touch the point on the circle directly below it.
Later, the researchers gave up on the laser pointer. Whichever direction the star projector was directed, both seals would eventually be able to swim in the direction of Sirius. It showed that the researchers He argued in a 2008 articleHe said seals that traverse the open sea have the capacity to use lodestars to guide their journeys.
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