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How do sharks smell blood underwater? © Getty Images

How do sharks smell blood underwater?

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Duuun dun... Duuun dun... dun dun dun dun dun dun. Sharks can smell blood from up to around a quarter of a mile away.

Asked by: Todd Michael Wilson, USA

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When you smell something in the air, it’s because scent molecules have dissolved into the wet lining of your nose. Smelling underwater is no different, except that the molecules are already dissolved in the seawater. It’s a myth that sharks can smell a single drop of blood from a mile away.

Sharks actually have roughly the same sensitivity as other fish and can detect smells at between one part per 25 million and one part per 10 billion, depending on the chemical, and the species of shark. At the top end, that’s about one drop of blood in a small swimming pool.

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Authors

luis villazon
Luis VillazonQ&A expert

Luis trained as a zoologist, but now works as a science and technology educator. In his spare time he builds 3D-printed robots, in the hope that he will be spared when the revolution inevitably comes.

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