At first coup d’oeil , the cuttlefish looks like a pretty easy meal . It ’s squishy , stubby , and seemingly defenceless . But the cuttlefish does n’t give up so well .
Like its cousins the devilfish and the squid , the cuttlefish has no external racing shell , and has therefore been forced to get creative in its defenses . Biologists and textile scientist alike are captivated by the cuttlefish’stalent for subterfuge . By compressing , stretch , or relaxing pigment and light - excogitate cells , the cuttlefish can alter color and even make patterns on its peel . As if that ’s not enough , they ’ve become shape - shifter , too . Any cuttlefish with a half - second ’s head start canvanish into its surroundings .
But all this razzle-dazzle - dazzle will only scotch predators who hunt by passel . Those that rely on olfactory property or touching wo n’t be fool , nor will those hunter who locate prey via electrosensing .
It ’s more usual than you ’d think . Every living affair gives off at least some electrical energy . Some , like the electric eel , carry a substantial direction . But most of us just trundle along , emit a swooning electric aura as we go about our daily business sector .
Scientists ’ list of creature that can sense other animals ’ electrical field is develop all the time , and a lot of those animals are aquatic . At the top of the listing are sharks , with electrosensing skills10,000 times more powerfulthan those of any other brute .
And what do sharks like to eat ? A lot of thing , including — you think it — the cuttlefish . Once again , it appear like the cuttlefish does n’t stomach a chance — and once again , calculate are lead astray . researcher recently discovered that cuttlefish can actually muffle their electrical fields , rendering themselves nearly invisible .
This insight comes good manners of Duke University life scientist Christine Bedore , who has made it her clientele to study electrosensing in ocean critter . Bedore found that the electric flying field devote off by the coarse cuttle ( Sepia officinalis)is quite weak , about75,000 times weakerthan a exclusive AAA battery . But even a watery field is still recognisable to a hungry shark .
To come up out how a cuttlefish responds to the batch of a shark , Bedore place an iPad sieve against the paries of a cuttlefish tank . She then played the cuttlefish videos of what take care like the silhouette of approaching crabs , sharks , and groupers ( another cuttlefish predator ) .
The crab silhouette , which presented no threat , did n’t urge any changes in the cuttlefish ’s behavior . But each time the silhouette of a shark or grouper come on , the cuttlefish in the tank froze . Its breathing slowed , and it seemed to be covering section of its torso with its little arms .
Throughout the experimentation , Bedore was tracking the cuttlefish ’s electric yield . Watch for yourself :
The cuttlefish ’s maneuver had a immense effect on the strength of its electrical field . By covering its siphons with its coat of arms , the cuttlefish cloak its electric output signal by as much as 89 percent .
For the second stage of the study , Bedore and her workfellow offered real shark access to a fake cuttle in two position : relaxed and frozen . The “ cuttlefish ” at rest was not only visible , but it was irresistible ; the sharks start out bite the equipment . The muted electric field of a frozen cuttle , on the other hand , attracted only one-half as many shark bite .
Bedore and her colleagues published their findings in the December 2 issue of theProceedings of the Royal Society B.
