Cuttlefish help develop submarine defences

The common cuttlefish hides from sharks by shutting down its own electrical field, US scientists have discovered.

Combined with its almost legendary ability to camouflage itself, the animal can virtually disappear.

And those skills may have ramifications for the defence industry, inspiring new ways to mask submarines and communications equipment.

The discovery was reported reported in the journal Proceedings of the Royal Society B. The study was co-funded by the US Office of Naval Research­.

They include instantly changing its colour and skin patterns — an extraordinary skill, given that the creature is completely colourblind. The newly identified ability is equally surprising, as cuttlefish cannot detect electric fields.

If cuttlefish are formidable at camouflage, sharks are equally skilled hunters. Part of their armoury is to use “electroreception” to detect the bioelectric field sea creatures exude as they extract oxygen from the water.

But the study found that cuttlefish have worked out how to reduce bioelectric cues by freezing, and blocking the holes that draw water into their bodies with their tentacles.

“The reduction of bioelectric fields created by the freeze-simulating stimulus resulted in a possible decrease in shark predation risk by reducing detectability,” the study says.

The biologists found that the response reduced the cuttlefish’s electric fields from around 26 microvolts to about six microvolts.

The researchers at Duke University in North Carolina said the findings could lead to defence strategies where the Navy insulates electrical devices to make them less detectable.

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