Christine Bedore at Duke University published a study on how cuttlefish can cloak their electrical fields when faced with the looming threat of a shark attack. Since sharks’ eyes aren’t very useful for what’s in front of them, they rely on sensitive detectors in their snouts to ferret out tiny electrical fields like the ones produced by a cuttlefish’s metabolic processes, such as breathing.
When Bedore used an iPad to simulate a shark’s silhouette, the cuttlefish would freeze in place, slow its ventilation, and reduce its bioelectric potential from about 10 to 30 microvolts down to six. A less-threatening crab silhouette garnered no such response. It’s a pretty neat trick that helps keep the soft and squishy cuttlefish off the menu.