If you've ever seen seals frolicking in the
water, you know they are agile swimmers, with perfectly adapted paddle-like
limbs. But if you think those flippers are just for swimming, then think again.
In a study published today in Royal
Society Open Science, we took a fresh look at how one group of seals – the
northern true seals, including grey and harbour seals – use
their forelimbs to process and eat their prey. This behaviour is rare among
living marine mammals, and shows how ancient seals evolved to feed in water.
What's in a flipper?
Seals are best known for having long,
streamlined forelimb flippers, much like those of a dolphin.
Flippers and fins are great for steering and
swimming, and independently evolved in many aquatic vertebrates: fish, seals,
whales, dolphins, turtles, and extinct marine reptiles such as plesiosaurs and
ichthyosaurs.
But northern seals are an exception. Rather
than wing-like, their hands are short, with mobile fingers that end in large
protruding claws.
Instead of flippers, they really have paws—more
like a dog than a dolphin. The question is: why?
The clawed seals of the north
The answer has to do with how these animals
eat. When watching how northern seals feed, both in captivity and in the wild,
we found that they don't just take a bite out of their catch.
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