The spinning dolphin has worked hard to maintain its nickname. In a spectacular jump into the air, they can perform up to 7 spins. Scientists are now explaining this tumbling mechanism using mathematical models and underwater footage.
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Dolphins must rotate their bodies underwater to achieve incredible speeds as they leap into the air. |
Before “taking off,” dolphins begin their rotation right from underwater. Using their flippers like wings, the animal starts to roll its body gently. This movement is relatively slow because its tail and flippers are pushing against the water, increasing drag.
It’s similar to waving your hand in a bathtub, says Anthony Nicastro, a physicist from West Chester University. “You can feel the resistance from the water you’re pushing around,” Nicastro explains. “Dolphins have flippers, a dorsal fin, and other water-resisting surfaces. Underwater, they can only spin 1-2 times per second.”
But once the animal breaks the surface, everything changes.
Once propelled into the air, dolphins shed all the drag that slowed them down underwater. That’s when everything is set for the spinning action. On the surface, a spinning dolphin can achieve up to 7 rolls in just one second.
Previous studies speculated that dolphins generate these spinning motions by twisting their bodies, but only after breaking the surface. “You can’t spin that much just with a smooth jump. It doesn’t make sense in a real-world model.” remarked biologist Frank Fish, also from West Chester University.
Through calculations, Nicastro’s mathematical model has accurately described how these spins occur.
But why?
No one knows for sure why dolphins spin like this. There could be various reasons: to display dominance, signal location, hunt prey, or simply for play.
It might also be an easy way to shake off pesky fish clinging to them, such as remoras—fish with dorsal fins that act like suction cups, attaching themselves to sharks and dolphins. They cause additional drag or irritate the dolphin’s sensitive skin. When dolphins leap into the air and spin, the remoras are dislodged.
“If the dolphin doesn’t spin, the remoras will stay firmly attached. Only the spinning motion can shake off these annoying parasites.” Nicastro stated.
T. An
