Sea hares don't look like they can put up much of a fight, but these bunny-eared slug cousins can really knock you senseless. When disturbed, sea hares (genus Aplysia) release a dark purple cloud that's made up of ink and a sticky, milky mix of chemicals called opaline. Today in The Journal of Experimental Biology, researchers show that the opaline in the ink cloud not only frightens and distract predators, but also interferes with their sensory organs and blocks their chemical receptors. To find its desensitizing secret, the scientists dabbed opaline extracts onto the antennae of spiny lobsters, which will hunt the hares when less well-defended prey is hard to come by. They then blasted some shrimp-scented water into the lobsters' tanks and watched how their chemosensory cells reacted to the smell of food. They found that opaline's sticky components alone could significantly decrease the cellular activity, suggesting that opaline strikes predators chemically "blind" by gumming up their chemical senses.
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