Yes, we've heard bees use the Earth's magnetic field to navigate by.
We've also heard about some bird species following the Sun to find the
location of their evening roost. But what do we know about the animals
living at sea? Do they use astronomical aids to help them find their
way around the planet? Mammals such as whales are known to exhibit
"skyhopping" behaviour when they surface from the water to
have a look around, but seals go one step further; they can recognise
and orientate themselves with the stars…
It was one of the first methods us humans used for navigation when
sailing across the middle of a featureless ocean, we'd pick out known
stars and constellations and relate them to our location on the
planet's surface. Explorers used astronomy to guide them to new lands,
captains used the stars to direct their battleships toward the enemy
and trade routes were repeatedly used thanks to star navigation. In
its most basic form, star navigation could be carried out by linking
stars with the location on the horizon when they rise, as was
traditionally done by Polynesian sailors to colonize vast numbers of
islands in the Pacific.
In a revealing study, researchers at the University of Southern
Denmark in Odense have discovered that seals have the ability to
recognise stars and groups of stars inside a modified planetarium. A
five-metre round pool plus two harbour seals were covered with a dome
with 6000 point light sources to simulate the Northern Hemisphere's
starry sky. Björn Mauck and his team found that if they selected an
individual star with a laser pointer, they could train the seals to
swim toward that star and then rewarded them with a treat if they did
it correctly. Then the researchers would randomly orientate the dome,
and without the help of a laser pointer, the seals would continue to
swim toward the correct star.
"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." - Björn Mauck
This study strongly suggests that these two harbour seals have an
amazing, natural ability to recognise the distribution of stars on a
clear night.
So when you next see a seal popping to the ocean surface, it might not
be simply checking out its surroundings, it might be trying to look
for Sirius in the constellation of Canis Major…
Paper abstract:
"Harbour seals (Phoca vitulina) can steer by the stars",
Mauck et al., 2008
Source: New Scientist
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