Even in a churning, turbulent ocean, sharks can sniff out the faint scent of prey from several kilometers away. How they do it has been a mystery. Now, a new study published  online today in Current Biology suggests a strikingly simple answer: Sharks compare which nostril receives a scent molecule first and then turn in that direction. Researchers fitted the smooth dogfish shark, Mustelus canis, with a headpiece that can dispense squid odor to either nostril at set delays. The researchers found that when they sprayed the odor into the sharks' nostrils at slightly different times, the sharks turned in the direction of the earlier spritz, which keeps the shark pointed toward the odor's trail. The finding could explain the hammerhead's odd head shape, as wider-set nostrils could help better triangulate prey.
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