Short periods of flapping wings alternating with long, gliding descent helps birds preserve energy in flight. Now researchers have discovered that sharks and seals can use the same technique to glide through the ocean.
Murdoch University’s Dr Adrian Gleiss led a team that attached accelerometers to whale sharks, white sharks, fur seals, and elephant seals.
They found that all four species performed the characteristic undulating flight of birds and bats, with periods of active, upwards propulsion alternating with slow, passive, gliding descents.
Adrian analysed the amount of effort it took for the seals and sharks to move this way, and showed that, just like birds, they’re saving energy.
The similarity is surprising considering the different evolutionary paths of sharks, seals, birds and bats – not to mention the different forms of propulsion by tail fin, pectoral fin and wing.
Adrian’s work at Murdoch University’s Freshwater Fish Group and Fish Health Unit revolves around understanding how ecology and physiology drive the evolution of animals. To this end, his team has recently developed a method to attach rigid bio-logging tags to marine animals via a long, specially-designed tagging pole and self-releasing clamps.
Removing the need to capture and release the animal for tagging, this is of benefit to the animal’s health. And in the case of monitoring dangerous predators such as white sharks, being able to keep a significant distance is of benefit to the researcher’s health too!
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