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Engineers and biologists join forces to reveal how seals evolved to swim
New research has combined cutting-edge engineering with animal behaviour to explain the origins of efficient swimming in Nature’s underwater acrobats: Seals and Sea Lions.
Seals and sea lions are fast swimming ocean predators that use their flippers to literally fly through the water. But not all seals are the same: some swim with their front flippers while others propel themselves with their back feet. Fur seals and sea lions have wing-like front flippers specialised for swimming, while grey and harbor seals have stubby, clawed paws and swim with their feet.
The reasons why these two different ways of swimming evolved has perplexed biologists for generations. But now a new study led by Australia’s Monash University and including scientists from London’s Natural History Museum has attempted to understand the evolution of these distinctive styles. Through using cutting-edge computer simulations alongside footage of live seals the team hoped to finally answer this mystery.
Dr Travis Park, a researcher from the Natural History Museum involved in the study, said ‘One of the key specimens used in this study was a female grey seal that was brought to the Natural History Museum after it’s remains were found in Margate. Along with help from the Royal National Orthopaedic Hospital, who CT scanned the animal for us, our scientists were able to turn this sad loss into a new understanding of how swimming in seals has evolved.’
The adult grey seal was found dead in Walpole Bay in Margate in 2018 and was brought to the Natural History Museum for study. As well as utilizing the animal’s limbs for this study the team at the NHM looked for parasites and investigated the animal’s stomach for a study into marine life ingestion of plastics. Interestingly in the course of the dissection the team found a metal object in the animal’s head which they believed to be the cause of death. The find was reported to the RSPCA.
Alongside real specimens such as the NHM seal, the team turned to simulations to help understand how different seals propelled themselves through the water. Lead author Dr Hocking of Monash University teamed up with engineer Dr Shibo Wang, from the university’s Department of Mechanical and Aerospace Engineering, and used advanced Fluid Dynamics simulations to show how water flows around seal flippers of different shapes.
Dr Hocking explains, ‘Our analysis showed that some Antarctic seals, like leopard seals, actually have very streamlined, wing-like forelimbs, despite being from the ‘foot-propelled’ seal family.’
This discovery shows how wing-like flippers can evolve in seals that already swim with their back feet, providing a pathway for the evolution of forelimb swimming in the fur seals and sea lions.
Dr Travis Park added,’ ‘We found that Grey seals still use their paws to hold their prey when processing it, but other seals like Leopard seals have foregone this ability to maximise their swimming speed and agility, being able to capture more mobile prey.’
As well as explaining the origin of seals, this study may also improve human design.
Dr Hocking concludes, ‘Seals have had millions of years to perfect their swimming, and they can teach us a thing or two about underwater grace and elegance. Learning from them may help us to improve the design of human-built machines like underwater drones and submersibles, increasing their speed, maneuverability or energy efficiency.’
The study Convergent evolution of forelimb-propelled swimming in seals is published in Current Biology.
Notes to editors
Natural History Museum Media contact: Tel: +44 (0)20 7942 5654 / 07799690151 Email: press@nhm.ac.uk
Images available to download here.
The Natural History Museum is both a world-leading science research centre and the most-visited natural history museum in Europe. With a vision of a future in which both people and the planet thrive, it is uniquely positioned to be a powerful champion for balancing humanity’s needs with those of the natural world.
It is custodian of one of the world’s most important scientific collections comprising over 80 million specimens. The scale of this collection enables researchers from all over the world to document how species have and continue to respond to environmental changes - which is vital in helping predict what might happen in the future and informing future policies and plans to help the planet.
The Museum’s 300 scientists continue to represent one of the largest groups in the world studying and enabling research into every aspect of the natural world. Their science is contributing critical data to help the global fight to save the future of the planet from the major threats of climate change and biodiversity loss through to finding solutions such as the sustainable extraction of natural resources.
The Museum uses its enormous global reach and influence to meet its mission to create advocates for the planet - to inform, inspire and empower everyone to make a difference for nature. We welcome over five million visitors each year; our digital output reaches hundreds of thousands of people in over 200 countries each month and our touring exhibitions have been seen by around 30 million people in the last 10 years.