In order for animals to run, swim or fly, science requires pressure needed to be exerted from the ground, water or air in order to propel themselves froward. However, in this new study, jellyfish and eels prove that this premise is false, when it comes to their ability to swim underwater.
Instead of propelling themselves by pushing water from their bottom, jellyfish and lampreys which are serpentine, jawless type of fish also known as lamprey eels apparently "pull" themselves in a forward motion to create a region of low pressure in the water that is directly in front of them.
According to co-author of the study John Dabiri from the University of Stanford, this low pressure is created on top of the jellyfish's umbrella type body that is totally different from previous scientific understanding of swimming dynamics where the flow is focused under this umbrella shape.
In this new study, he adds that measuring this pressure for the first time on how swimming animals exert force on surrounding water, shows this mechanism as an efficient swimming technique that is quite different from traditional settings.
New data obtained from this swimming mechanism can lead to better designs for energy efficient submarines, since the focus of current biomechanics and engineering studies rely on high pressure propulsion as opposed to this study's key finding which is low pressure.
Dabiri adds that this suction based mechanism that is observed in jellyfish and eels can be adapted to engineered vehicles where it can ultimately result in significant energy conservation.
For lampreys, high pressure is produced when they push liquid molecules together via a sideways body movement that is similar to a swimmer's hands pushing water with his hands while swimming.
Dabiri says that low pressure can also be created in many ways such as body rotation to create swirling vortices where low pressure areas lie inside there center. He also says that this mechanism requires much less energy to create enough propulsion as opposed to high pressure which is more commonly used.
This new study is published in the journal Nature Communications.