Cuttlefish Can Elude Sharks With Crafty Arm-Tossing [WATCH]
Apparently, cuttlefish -- squid-like creatures -- are a tasty morsel to many other fish, and they spend much of their time evading those who would nibble on their appendages.
But they have a technique, which is good. The cuttlefish, Sepia officinalis, has a type of visual camouflage, and it also hides its electrical fields, a new study by Duke University found, according to a release.
The latter skill is handy in eluding its major predator, the shark. While sharks cannot see well in front of and near their mouths because their eyes are on either side of their heads, they can sense all kinds of faint electrical fields emanating from other fish and creatures.
Normally, sharks can pick up the faint current from the cuttlefish's tube-like siphons that are on either side of its head. They also can sense the vent where the fish excretes and the opening around its mantle, said the release. (Scroll down to read further...)
A cuttlefish has a current that is something like 75,000 times less strong than an AAA battery. However, the fish can slow its ventilation, toss its arms around to conceal siphons and clamp down on its mantle to cause the current to decrease to about 6 microvolts, the release confirmed.
"There's a myth that sharks detect the electrical signals of your heartbeat," Bedore said in the release. But skin and other tissues effectively mask those signals. Bedore found that the cuttlefish's arms over the siphons reduced the bioelectric field by as much as 89 percent.
The study recently was published in the journal Proceedings of the Royal Society B.
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