Thursday, January 15, 2015

The Eel's in Charge

By: Paul Carvalho

Before Jack Cover of NASA developed the Taser stun gun, evolution and natural selection whipped up these bad boys.



The electric eel (Electrophorus electricus) is capable of discharging electricity for navigation, defense, and attack purposes.  They shock their prey into a stupor until the helpless fish twitches uncontrollably. Once the eel feels a slight movement in the water from the twitch, they attack and the fish is a goner. Recently, researchers at Vanderbilt University in Nashville, Tennessee have discovered that eels can also use their shocking ability to remotely control prey items. 



Electric eels (endemic to South America), and many other electrogenic fish in the order Gymnotiformes have evolved an insane cell known as the electrocyte. They are derived from muscle cells and have lost the ability to contract, however, these cells have developed into natural batteries within the eels.  Most electrogenic fish have one electric organ made up of these cells, but this gangster fish contains THREE electric organs (Sachs, Main, and Hunter’s) running along the whole body. All three add up to 6,000 electrocytes allowing this beast to generate 600 volts- that is five times that of a U.S. wall outlet!



Electric eels have three forms of emitting electricity from their organs. The first is used for navigation and consists of low-voltage pulses.  The second is a high-voltage pulse, released in pairs or triplets for hunting, typically used in a complex environment with a lot of hiding places for tasty snacks. The third is a series of high-voltage pulses used for freezing free-swimming prey animals in their tracks. The third form can also be used as a defense mechanism against haters, like the caiman featured in the video below. 

Be aware of the creepy clown laugh in the beginning and end of this video!



Although these forms of electrical discharge have been known for quite some time, little was known about the impact of the discharge on prey. Kenneth Catania from Vanderbilt University designed an experiment to explore how the electrical charge affects prey during an attack. To examine the effects of high-voltage discharge on prey, Catania set up a tank with a gel barrier permeable to electrical current. A scramble-brained fish fixed to a device that measured muscle tension was lowered into one side of the tank with a hungry eel on the other side. Worms were dropped into the eel’s side of the tank in order to initiate an attack response. The fish’s muscles contracted during this test, indicating that the muscles of the prey are FORCED to contract during an attack (A and B in the following figure).



Catania suspected that muscle contractions in the fish may be directly caused by the electrical charge stimulating muscle cells or by stimulating motor neurons in the prey. To explore these options, two fish were placed side by side in the gel-divided tank. One fish was injected with an acetylcholine antagonist (basically a shot disrupting the interaction between the motor neurons and muscle cells) and the other fish was injected with a control. The results seen in the above figure (C and D), show that the tension in the acetylcholine antagonist-treated fish declines to nothing after injection. This reveals that fish motor neuron activity is necessary for the eel’s electrical discharge to affect muscle contraction in prey.

Now let’s talk about that second form of electrical discharge mentioned above. Eels will sometimes use high-voltage pulses in doublets or triplets while hunting. Catania noticed that eels would release an isolated doublet and wait for prey to tweak out. Once the eel detected the prey’s movement in the water, the eel releases the attack response, much like we were just talking about. This attack stuns the prey so it can move in for the kill. To test his theory, Catania put a fish in a plastic bag inside some gel and hooked it up to a machine that the experimenter can use to stimulate a twitch in the fish. The fish was also protected from the electrical doublet sent out from the eel, so unless the researcher induces the twitch, the eel has no clue anything is there.

When the eel released its doublet, the researcher stimulated the fish to twitch. In response, the eel used a high voltage pulse and tried to attack the fish. This happened every time the experimenter simulated a twitch in the fish. When a doublet was released and the researcher did not simulate a twitch, the eels did not gear into attack mode- it was just business as usual.



Now this is truly amazing! At least I think so. These eels can swim around cracks and holes and not detect a prey item but with this “doublet hunting” method they can remotely control the muscle contraction of some poor unfortunate soul giving away their position and leading to their demise.

Now if you ever go to South America looking for some electric eels, learn a thing or two from the following video before you embark on that journey.


References:
Catania, K. 2014. The shocking predatory strike of the electric eel. Science 346:1231-1234.

de Santana, C.D., R.P. Vari, and W.B. Wosiacki. 2013. The untold story of the caudal skeleton in the electric eel (Ostariophysi: Gymnotiformes: Electrophus). PLoS ONE 10:1371.

Keynes, R.D. and H. Martins-Ferreira. 1953. Membrane potentials in the electroplates of the electric eel. The Journal of Physiology 119:315-351.

Weber, B. 2009. Jack Cover, 88, physicist who invented the taser stun gun, dies. The New York Times.

Images:
http://knowyourmeme.com/memes/are-you-a-wizard
http://www.robinsonlibrary.com/science/zoology/fishes/actinopterygii/electriceel.htm
http://www.quickmeme.com/meme/gb7


6 comments:

  1. Whether a seasoned hunter or just getting started one of the most important factors is to understand current deer hunting regulations. Deer hunting regulations are created and enforced for a reason. sihunting

    ReplyDelete
  2. Are you a bow hunting beginner looking to master this unique and ancient method of hunting game? The sport of bow hunting has gained a lot of popularity over the last fifty years. Many sportsman like the greater challenge of hunting an animal with a bow, rather then with a high powered hunting rifle. huntingmastery.blogspot.com

    ReplyDelete
  3. Healing from HIV-AIDS, i never though dr.camala who could ever get my HIV-AIDS cured with his healing spell, i have tried almost everything but i couldn't find any solution on my disease, despite all these happening to me, i always spend alot to buy a HIV drugs from hospital and taking some several medications but no relieve, until one day i was just browsing on the internet when i come across a great post of !Michelle! who truly said that she was been diagnose with HIV and was healed that very week through the help of these great powerful healing spell doctor, sometime i really wonder why people called him Papa camala, i never knew it was all because of the great and perfect work that he has been doing that is causing all this. so i quickly contacted him, and he ask me some few questions and he said a thing i will never forget that anyone who contacted him is ! always getting his or her healing in just 6 hours after doing all he ask you, so i was amazed all the time i heard that from him, so i did all things only to see that at the very day which he said i will be healed, all the strength that has left me before rush back and i becomes very strong and healthy, this disease almost kills my life all because of me, so i will to hospital to give the final test to the disease and the doctor said i am HIV negative, i am very amazed and happy about the healing dr.camala gave to me from the ancient part of Africa, you can email him now for your own healing too at: dr.camalahivadscure@yahoo.com or WhatsApp him +2349055637784 thank you sir for healing me from HIV, i am Doris Carter.

    ReplyDelete
  4. I was cured from my herpes Disease. after suffering since 4years ago. but when i contact doc onokun on the internet. he gave me a Natural cure that ended my suffering after using it for two weeks. i went to check myself on the hospital and i was tested negative. I can't more happier but to say thank you sir and i use this medium to say to everyone don't waste any time to contact this powerful herbal Dr,onokun On any Kind of Disease he is Ready to help you. You can reach him through his email: dronokunherbalcure@gmail.com

    ReplyDelete
  5. I Want To Appreciate Dr.OYAGU for his great deeds, I Was Diagnosed With type 2 Herpes Virus Last year,And i Was Looking For Solution To Be Cured Luckily I Saw Testimonies On How Dr.OYAGU Cure Herpes Virus I Decided To Contact Dr.OYAGU I Contacted Him He Prepared A Herbal Medicine Portion And Sent It To Me,I Started The Herbal Medicine For My Health.He Gave Me Step By Step Instructions On How To Apply It, When I Applied It As Instructed, I Was Cured Of This Deadly Herpes Within 2 weeks, I Am Now Herpes Negative.My Brother And Sister I No That There Are So Many People That Have The Same Herpes Virus Please contact Dr OYAGU To Help You Too,And Help Me To Thank Dr.OYAGU For Cure Me, I’m Cured By Dr. OYAGU Herbal Medicine,His Contact Email:oyaguherbalhome@gmail.com

    Or Cell Whatsapp Number +2348101755322 thank you

    ReplyDelete
  6. I has suffered for Human papillomavirus HPV) for 2years, I was given some tablets at the hospital but I refused to take it, They said I have to be on it for life so I don't want take a drugs everyday for life. No point in taking medicine everyday when u won't get cure from it and I was advice to seek for natural herbal cure, after some time I found dr onokun is the most trustful herbalist that have herbs to cure wicked symptom's,I emailed dr onokun, for 2weeks been his patient he cured my (HPV) with his herbal. I only used his natural herbs for two weeks it was 100% cure. I'm not (HPV) patient anymore. I'm happy about it i finally got cured out of this mess been in my body for 2years. I also recommend you if you're living with (HPV) or herpes symptoms i also want you to be free contact dr onokun with the email attach to my post. Dronokunherbalcure@gmail.com

    ReplyDelete