Natures wonders: electric eels special sense (Introduction)

by David Turell , Thursday, October 22, 2015, 13:43 (3318 days ago) @ dhw

They strike with high voltage and then have an 'electrosense' to capture the prey:-http://www.nature.com/ncomms/2015/151020/ncomms9638/full/ncomms9638.html-"Electric eels (Electrophorus electricus) are legendary for their ability to incapacitate fish, humans, and horses with hundreds of volts of electricity. The function of this output as a weapon has been obvious for centuries but its potential role for electroreception has been overlooked. Here it is shown that electric eels use high-voltage simultaneously as a weapon and for precise and rapid electrolocation of fast-moving prey and conductors. Their speed, accuracy, and high-frequency pulse rate are reminiscent of bats using a ‘terminal feeding buzz' to track insects. Eel's exhibit ‘sensory conflict' when mechanosensory and electrosensory cues are separated, striking first toward mechanosensory cues and later toward conductors. Strikes initiated in the absence of conductors are aborted. In addition to providing new insights into the evolution of strongly electric fish and showing electric eels to be far more sophisticated than previously described, these findings reveal a trait with markedly dichotomous functions.-"High-voltage onset and head translation toward a water disturbance likely allows the eel to ‘acquire' the conductive prey with its longer range, high-temporal resolution electrosensory system. This suggestion is supported by the artificial separation of mechanosensory and conductance cues during experiments (Fig. 2). Eels started towards the water movement, but used active electrosensory feedback to guide the final strike towards the conductor. Although the separation of cues was artificial in the laboratory, a water movement cue in nature could emanate most strongly from the former position of an escaping fish27 making electrolocation the most accurate sensory modality for guiding pursuit. And unlike mechanoreception, active electroreception is presumably unaffected by the eel's own movement through the water. Finally, the ability to simultaneously immobilize and track prey with high voltage is an unusual combination of dichotomous functions. These results cast the electric eel in a new light, as both a formidable predator and unique sensory specialist."-Comment: Like Darwin, I wonder how this evolved.