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Author Topic:   The Electric Eel - more evidence against evolution
Coyote
Member (Idle past 2106 days)
Posts: 6117
Joined: 01-12-2008


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Message 4 of 101 (665590)
06-14-2012 11:49 PM
Reply to: Message 1 by fred2353
06-14-2012 10:37 PM


Electric organ discharges are common
Sorry to rain on your parade, but there are quite a few species which exhibit what are called "electric organ discharges."
From a recent article:
The electric organs specialized for generating either low or high voltage or high current pulses are modified from muscle cells or from branched nerve endings. Electric organ cells (electrocytes) maintain a standing emf between inside and outside by ion pumps, like ordinary cells. They can be discharged by brief signals from the synchronized electromotor nerve cells in the spinal cord, under brain control. Nerve endings by one of several arrangements first discharge one face of the electrocytes and then the other, while the faces are anatomically patterned to add their pulses either in series (electric eel) or in parallel (Torpedo).
Diversity is conspicuous in the temporal pattern of electric organ discharges (EOD). Some species are called pulse fish because the EODs iterate at a low and irregular repetition rate (intervals several to many times the duration of the single pulse). Others are wave fish because the intervals are brief and regular (equal to or little longer than discharge duration) — reaching regularities higher than any other known biological rhythms. Each discharge is commanded by a special brain nucleus that receives and integrates multiple inputs and is usually relayed through one or more synapses in the brain stem and again in the spinal cord, besides the last junction between efferent axon and electrocyte. The regularity of the EODs can be controlled by the brain and routinely shows a very small variation. It is not yet clear what situations or states of the brain are associated with higher or lower regularity or what selective advantage such extremely low variation confers. Presumably this advantage lies in the domain of detecting or assessing objects that distort the instantaneous electric field of the EOD — the signal analyzed by the electroreceptive system. Source
From this article, it appears that there is quite a range of electric organ discharges among different species.
Electric organs are known in some species of skates (rajoid elasmobranchs) and electric rays (torpinoids), without clear indication whether there was only one or more than one independent invention. The EOD of skates is weak and probably mainly functions in communication between members of the same species, for example in reproductive behavior. The EOD of Torpedo is high in current but low in voltage and, whatever else it does, certainly contributes to catching prey fish by disorienting their swimming. Electric organs are known in a number of bony fish, including several species and maybe whole families of catfishes (Siluriformes) including one with a strong EOD (Malapterurus), the others being weak, presumably social communicating systems; probably all of the New World knife fishes (Gymnotiformes) which includes the classical, high voltage, low current electric eel (Electrophorus), all species of the African order of Mormyriformes (elephant nose and many others); one family of stargazers (Astroscopidae) with EODs of very moderate strength and quite unknown function. It seems likely that evolution has discovered how to make and make use of electric organs at least five times, independently and possibly more — an outstanding case of parallel evolution, possibly exceeded however by the number of plesiomorphic features independently invented for electroreception. Diversity on the motor side includes a variety of forms of innervation of the electrocytes in mormyrids, where these cells have stalks that in some species penetrate the flat disk-like electrocyte and receive motor nerve endings at a circumscribed part of the stalk. Studies of the mitochondrial DNA sequencing of many species permit conclusions about which form of innervation was primitive and which was derived and agree very well with phylogeny based on anatomical characters (Alves-Gomes and Hopkins, 1996).
From this one article alone, found during a brief google search, it appears that all of your points are refuted.
Unless you have more information than you posted in your initial post, the evidence that is easily found on the web suggests the opposite of what you are claiming: it suggests an evolution of electric organ discharges among a variety of species, along with the kind of diversity that would be expected from natural origins.

Religious belief does not constitute scientific evidence, nor does it convey scientific knowledge.

This message is a reply to:
 Message 1 by fred2353, posted 06-14-2012 10:37 PM fred2353 has not replied

  
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