Cuttlefish can go into electric stealth mode

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Cuttlefish can go into electric stealth mode

December 04, 2015 - 20:28
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Not only do these squid-like creatures employ stealthy visual camouflage when a predator looms nearby, new research shows they also manage to cloak their electrical fields.

Cuttlefish are capable of changing colour and pattern (including the polarization of the reflected light as well as the texture of the skin.

Sharks home in on faint bioelectric fields generated by the bodies of their prey which they pick up using sensitive detectors on their snouts.

When researchers from Duke University showed captive cuttlefish held in a tank videos depicting the menacing silhouettes of a shark or predatory grouper fish they reacted by lowering the electric field dramatically. Being shown the shadow of a harmless crab produced no reaction.

When the animal feels threatened it freezes and drops the current down from 10-30 microvolts to about six microvolts by covering body openings, the main source of the electric field, with its arms and breathing more slowly.

Cover up

It does this by covering body openings, the main source of the electric field, with its arms and breathing more slowly. Just the cuttlefish's arms over the siphons reduced the bioelectric field by as much as 89 percent.

Should the freezing trick fail, the cuttlefish's last-ditch defense is to squirt a cloud of ink and jet away with a powerful blast from its mantle and siphons. But those actions create an electrical signal about four times greater than the resting field.

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