Seals evolved their swimming style in multiple ways, says expert

The secret to seals’ unusual swimming style has been modelled using computer simulations of a beached seal in Kent.

Travis Park, biologist and palaeontologist at the Natural History Museum has worked on an international research team led by Dr David Hocking investigating the divergent swimming styles of various marine creatures.

Park’s team have studied scans submitted of various beached marine animals around the world and discovered that the evolutionary history of seals divides them into eared and earless seals, both using different swimming styles to suit their lifestyle.

The earless seals utilise a more traditional paw, with webbed fingers and the dexterity of these fingers allows them to catch fish in their hands and carry it onto land before eating.

The eared seals are optimised for a different aquatic lifestyle as with much larger flippers and no fingers they instead rely on their flexible necks to grab food while swimming.

The swimming styles have somewhat converged, with both groups relying more heavily on their forelimbs to generate speed.

The neck is less flexible because they rely more on their fingers.
EARLESS: The forelimb of an earless seal has distinct fingers that can be manipulated

What the team discovered more recently is that the several species of earless seals have evolved the same flipper design as their eared cousins.

This convergent evolution can be found frequently in organs vital to a species’ survival, such as eyes.

The diverse disciplines of the team have been a boon to the research process, contributing expertise in different areas and providing helpful scrutiny of each other’s work.

The computer model that models the swimming motion was created by the team’s engineers, who also hope to adapt the biological structures to improve the design of water vehicles.

The field of biomimetics looks extensively to the natural world for inspiration on how to improve human engineering.

The evolutionary journey of the seals is far from over, and the simulations could potentially allow for prediction of how the creatures will adapt to future circumstances in the oceans.

They look so regal
EARED: What it lacks in fingers it makes up for with ears

Park described how the changes in available food to smaller fish might require seals to adapt their swimming style with higher burst speeds and quick turns to follow them.

On the other end of the evolutionary arms race, the fish that seals chase is under constant pressure to evade capture.

Park compares this contest to the Red Queen’s Race from Alice in Wonderland.

He said: “You have to keep running to stay in the same spot.”

Park also spoke with glowing passion about the animals he studies, both living and extinct.

He said: “Apart from dinosaurs, seals are the most charismatic animals.”

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