To snap up fish, bottlenosed dolphins may rely on more than just sharp sight and sonar detection. The creatures might also pick up on the weak electric pulses prey produce each time their hearts beat or air filters through their gills.
The ability to detect the electrical signals living things give off is called electroreception. It has been previously documented in fish, amphibians and sharks (SN: 6/27/16). But it was only in 2011 that the Guiana dolphin made the list, as researchers discovered telltale sensory receptors hidden in an organ on the animals’ snouts (SN: 7/27/11).
In 2022, Hüttner and his colleagues identified the same structure in bottlenosed dolphins and confirmed that the creatures could detect electric fields on the scale of 0.5 millivolts per centimeter (or 500 microvolts), similar to those that some large fish and crustaceans emit. The new finding suggests that common bottlenosed dolphins (Tursiops truncatus) can likely make out the much subtler signals emanating off the majority of fish, the team reports November 30 in the Journal of Experimental Biology.
For the new study, the researchers trained Dolly and Donna to position their snouts in a metal apparatus and to swim away if they could sense an electrical impulse delivered to their sensory organs. The dolphins proved sensitive to both direct current and alternating current, two forms of electricity that living things generate. The dolphins excelled, however, at detecting direct current, which produces a steady signal. Donna picked up on fields as low as 5.5 microvolts and Dolly on those of 2.4 microvolts.
2023-11-30 18:00:00
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