Electric eels have captured the attention of scientists — and the public — for centuries. These aquatic animals can deliver a jolt of electricity to track and tucker out their prey. They also can use that shock as a defense mechanism. When an eel feels threatened, it leaps out of the water and zaps a perceived predator. Now a scientist has deliberately subjected himself to such an attack. His goal: to get a better picture of the fish’s shocking prowess.
Kenneth Catania is a biologist at Vanderbilt University in Nashville, Tenn. He wanted to know how strong of a shock an electric eel could deliver. So he stuck his arm in a tank and let a small eel zap him. At its strongest, the fish delivered a 40- to 50-milliampere current into his arm. It takes only 5 to 10 milliamperes of electricity for humans to lose control of their muscles and let go of the object that is shocking them. So it’s no wonder Catania involuntarily pulled his arm away with each electrical jolt this eel delivered. He presented his findings September 14 in Current Biology.
His test subject was just 40 centimeters (16 inches) long. Based on his tests with this fish, Catania has now estimated how much electricity someone might receive from a run in with an eel 1.8 meters (5 feet 10 inches) long. That’s the average length of an adult one of these eels living in the Amazon of South America. A human could receive a zap of 0.25 ampere, or 63 watts, he now calculates. That’s some 8.5 times more than a police-issued TASER gun. Enough to make a heart beat uncontrollably, this could kill a human.
- Roughly how many milliseconds worth of data are displayed on the x-axis in this graph?
- According to the graph, what is the approximate electric current measured at 125 milliseconds into the recording? Be sure to use appropriate units in your response.
- How many milliamperes are in one ampere? How many centiamperes are in one ampere? Convert your answer from question 2 to amperes, centiamperes and kiloamperes (write your answer in scientific notation).
- If you had to change the units used on the y-axis to either centiamperes or kiloamperes, which would you choose and why?
- Critique the graph. What would you do differently? What information do you feel could be added to the graph to make it more useful or easier to understand?
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