The evolution of electric eels
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23-02-2013, 11:19 AM
The evolution of electric eels
Do we have any evolutionary biologists visiting this site? With expertise in marine biology and freshwater zoology? If so, do you know anything about the evolution of this guy?

[Image: electric-eeld.jpg]

This is an electric eel (E. Electicus). This swimming stun gun isn't a real eel but from a family of knifefishes which .are closely related to catfish. They are native to the Amazon and Orinoco river basins of South America and one of the most dangerous fish that you can encounter. It has a number of very unique biological features, not the least of which is the ability to generate and deliver electric shocks of over 650 volts! The fish also utilizes a sort of active bioelectric radar system both to navigate in the murky waters as well as to search for prey. Electric eels are also airbreathing fish; their mouth functions like a lung, requiring the fish to surface for a gulp of air every now and then. The electric weapon the eel has makes it an apex predator like bengal tigers or humans; anyone foolish enough to attempt to make a meal out of E. Electricus quickly learns never to do so again.





Strangely enough only about 15-20% of the eel's length contains they head, body and all of its major organs. The remaining 80-85% of the animal is a giant biological battery. It's made up of three organs, the main electric organ, the Hunter's organ and the Organ of Sachs. The main organ and Hunter's organ are responsible for generating the electric charge the eel uses to shock it's prey. They are are giant mosaics of cells called electrocytes which are believed to have evolved from muscle cells. The individual electrocytes are connected together into stacks about 5000-6000 cells long, effectively becoming a string of batteries wired in series. Each electrocyte produces a potential of 0.1 volts so a stack can produce about 600V. The stacks are then connected in a manner parallel to each other building up a current. The end result is that a provoked adult eel can deliver 1 ampere of current at over 600 volts. This is quite capable of electrocuting an adult human being.

The eel's myoelectric locating system facilitated by the Organ of Sachs is fascinating as well. It appears to have both passive and active modes whereby the fish can generate a weak electric field then detect disturbances in it (sort of like a RADAR set). It can also receive and track the weak electric fields generated by the nervous systems and muscle contractions of nearby animals. As this guy demonstrates feeding hapless goldfish to his pet electric eel (they're predators so they have to eat live food, PETA), the electric fields of the tank are connected into an amplifier and through speakers. You can hear the small taps from the Organ of Sachs followed by the massive electric discharges as the eel stuns its prey.





Creationists would argue that E. Electricus is another example of irreducible complexity; no animal that complicated or dangerous could have just evolved. Obviously this is wrong on many levels. First off, the electric organs bear a strong resemblance to muscle cells and even muscles produce a small amount of electricity when contracting. Second, the animal need not have instantly changed into its current state; rather environmental pressures slowly favored this transfomation in the population, over time resulting in the fish we see today. Third, E. Electricus isn't a perfect system. The animal has sacrificed a great deal of mobility for these attributes as well has the electric discharges have terrible health consequences for the eel. Most eels become blind from cataracts on their eyes, a result of damage done from the discharges. They rely totally on their electrolocation system to find their way. The main organ systems of the body suffer as well from the high voltage jolts; the eel has evolved some defense for this in the form of a layer of fat around the vital organs and the brain but it's not fool proof. Hardly a perfect design.

So does anyone out there have more knowledge on the evolution of electric fishes?

"IN THRUST WE TRUST"

"We were conservative Jews and that meant we obeyed God's Commandments until His rules became a royal pain in the ass."

- Joel Chastnoff, The 188th Crybaby Brigade
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23-02-2013, 11:40 AM
RE: The evolution of electric eels
(23-02-2013 11:19 AM)Carlo_The_Bugsmasher_Driver Wrote:  Do we have any evolutionary biologists visiting this site? With expertise in marine biology and freshwater zoology? If so, do you know anything about the evolution of this guy?

[Image: electric-eeld.jpg]

This is an electric eel (E. Electicus). This swimming stun gun isn't a real eel but from a family of knifefishes which .are closely related to catfish. They are native to the Amazon and Orinoco river basins of South America and one of the most dangerous fish that you can encounter. It has a number of very unique biological features, not the least of which is the ability to generate and deliver electric shocks of over 650 volts! The fish also utilizes a sort of active bioelectric radar system both to navigate in the murky waters as well as to search for prey. Electric eels are also airbreathing fish; their mouth functions like a lung, requiring the fish to surface for a gulp of air every now and then. The electric weapon the eel has makes it an apex predator like bengal tigers or humans; anyone foolish enough to attempt to make a meal out of E. Electricus quickly learns never to do so again.





Strangely enough only about 15-20% of the eel's length contains they head, body and all of its major organs. The remaining 80-85% of the animal is a giant biological battery. It's made up of three organs, the main electric organ, the Hunter's organ and the Organ of Sachs. The main organ and Hunter's organ are responsible for generating the electric charge the eel uses to shock it's prey. They are are giant mosaics of cells called electrocytes which are believed to have evolved from muscle cells. The individual electrocytes are connected together into stacks about 5000-6000 cells long, effectively becoming a string of batteries wired in series. Each electrocyte produces a potential of 0.1 volts so a stack can produce about 600V. The stacks are then connected in a manner parallel to each other building up a current. The end result is that a provoked adult eel can deliver 1 ampere of current at over 600 volts. This is quite capable of electrocuting an adult human being.

The eel's myoelectric locating system facilitated by the Organ of Sachs is fascinating as well. It appears to have both passive and active modes whereby the fish can generate a weak electric field then detect disturbances in it (sort of like a RADAR set). It can also receive and track the weak electric fields generated by the nervous systems and muscle contractions of nearby animals. As this guy demonstrates feeding hapless goldfish to his pet electric eel (they're predators so they have to eat live food, PETA), the electric fields of the tank are connected into an amplifier and through speakers. You can hear the small taps from the Organ of Sachs followed by the massive electric discharges as the eel stuns its prey.





Creationists would argue that E. Electricus is another example of irreducible complexity; no animal that complicated or dangerous could have just evolved. Obviously this is wrong on many levels. First off, the electric organs bear a strong resemblance to muscle cells and even muscles produce a small amount of electricity when contracting. Second, the animal need not have instantly changed into its current state; rather environmental pressures slowly favored this transfomation in the population, over time resulting in the fish we see today. Third, E. Electricus isn't a perfect system. The animal has sacrificed a great deal of mobility for these attributes as well has the electric discharges have terrible health consequences for the eel. Most eels become blind from cataracts on their eyes, a result of damage done from the discharges. They rely totally on their electrolocation system to find their way. The main organ systems of the body suffer as well from the high voltage jolts; the eel has evolved some defense for this in the form of a layer of fat around the vital organs and the brain but it's not fool proof. Hardly a perfect design.

So does anyone out there have more knowledge on the evolution of electric fishes?


And fourth, electric generation and sensing has evolved separately several times.

Skepticism is not a position; it is an approach to claims.
Science is not a subject, but a method.
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23-02-2013, 11:42 AM
RE: The evolution of electric eels
(23-02-2013 11:40 AM)Chas Wrote:  And fourth, electric generation and sensing has evolved separately several times.
Indeed.

http://blogs.discovermagazine.com/notroc...Sj-n8qyIXE
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23-02-2013, 01:02 PM
RE: The evolution of electric eels
(23-02-2013 11:42 AM)Vosur Wrote:  
(23-02-2013 11:40 AM)Chas Wrote:  And fourth, electric generation and sensing has evolved separately several times.
Indeed.

http://blogs.discovermagazine.com/notroc...Sj-n8qyIXE

Interesting read. I guessed that fish gained the electric sensing ability first. And it may also explain why each species of electric fish had so few relatives with electric abilities.

"IN THRUST WE TRUST"

"We were conservative Jews and that meant we obeyed God's Commandments until His rules became a royal pain in the ass."

- Joel Chastnoff, The 188th Crybaby Brigade
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