According to new research, many marine animals may have independently learned to optimize their swim strokes in the same way.
A tiny cuttlefish and a huge stingray don’t look like they have much in common. Genetically and morphologically, they don’t. But even though their bodies are totally different shapes, it seems that both follow the same mechanical rules when they swim: Their long fins both ripple lengthwise and oscillate from side to side. And for both, the length of one undulation during swimming divided by the height of the sideways movement is always a ratio of around 20.
In fact, at least 22 marine animals have exactly the same ratio.
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