The Reason Behind Why Electric Eels Don’t Shock Themselves
This question amazes us all and is the most widespread question that is asked by everyone “Why don’t electric eels shock themselves?” As they are in the same water as the prey they attack and current is being generated right inside their bodies. But surprisingly they do shock themselves. Electric eels have been caught in the process of shocking something to have curled up a bit and thrash about as itself was also being shocked. But this shock that they experience repeatedly doesn’t injure them. As with the whole world evolving to different environments these electric eels must have also evolved to be resistant to the shocking pain, so they might feel the shock throughout their body but it does not trouble them as much as the effect it has on other animals, or you could also say that eel is insulated from its own shocks.
But if the eel is going to shock the water and the prey the eel has to be electrically open to current going out and returning. As seen from the diagram above you can see that the eels main vital organs are in the head. So this makes it likely that the eel is electrically constructed so that its head and all the internal organs are insulated properly so all the current flows out and back into the rest of the body of the eels.
How Electric Eels Produce Electricity
The answer is, all living things produce electrical charges from their cells. However in an electric eel they have thousands of modified muscle cells called electrocytes inside the thick tail where they are lined up just like batteries in an ordinary flashlight. Each one of the cells tends to generate about 0.15 volts, which is measured in EMF which is basically the rate at which energy is drawn from a source that produces a flow of electricity in a circuit, which is expressed in volts. In a fully grown electric eel sex thousand cells could be stacked to make one large battery that can be competent to generate as much as 600 volts for one short pulse. If you compare this to a normal car battery which generates a mere 12 volts, you can see that an electric eel has 50 times the shocking power of a car battery.
The electric eel, also interestingly has three separate for where it produces charge. The need for having three separate organs around the body is to perform the separate roles and applications of its capability to generate electricity.
The Hunter’s & Main organs are used to generate high voltages of power in order to use for protection , fright reflexes and to stun any prey. The Sach’s organ is only able to generate low pulses of electrical energy as its function is mainly for communication and navigation.
Here are electrocytes stacked in a particular arrangement, each stack being insulated from the next. Every stack of thousands of electrocytes acts as a battery that can make voltages of up to 600V. The separate stacks of cells then combine to give the electric eel the ability to generate a sizeable pulse of electricity. Ordinary pure water is a poor conductor of electricity compared to the waters of where electric eels live which have more salts and other minerals which make them conductors. When an electric eel generates electricity and shocks the water the current flows out the front of the eels body, through the water and then back into the eels tail. Any other living things in the water will feel the stunning and shock effect from the electric eel’s current as it goes through them.
How These Electrocytes Generate Electricity
As I just mentioned briefly, each cell generates small electrical charges. This is done by primarily by moving various positive ions which are molecules or charged atoms of metals like calcium, sodium and potassium out of the cells which makes the outer side of the cell have a positive charge compared to in the inside of the cell. The ions could move back inside all of the cells to equalize all the charges differences, but its known that cells continually pump ions out of the cells which is all part of a cell chemistry. The resting voltage is usually about 0.085 volts, as this isn’t very high but its uniformly spread around the outside of each cell, this makes all the outside of the cells positively charged and the inside negatively charged. By having this arrangement they can generate heaps of amount voltage.
The eels electrocytes cells are different though, as they aren’t symmetrical, they have a smooth side that is connected to all their nerve fibres. All these electrocytes are in a stack and oriented in the same direction with the smooth side towards the tail and the convoluted side towards the head.
Positive ions rush into the cells by nerve fibres sending signals to an electrocyte which are special pores on the smooth side of the cell openings. This momentarily makes additional charge across the cell membrane on that side of the cell usually about 0.065 volts. As an alternative of having a positive outside and a negative inside, the cell momentarily has a volt of 0.085 voltage difference across the convoluted side, and likewise an oriented charge average of 0.065 volts on the smooth side. These charges are all essentially stacked in series so that the end outcome is a brief charge transversely the complete cell of about 0.15 volts (0.085+0.065).
The issue behind all of this though, is that the directed orientation of the charges doesn’t last very long. Basically, the pores on the smooth side close leaving the cell to revert back to its resting state. So if a ordinary, normal nerve signal went out from the brain to each electrocyte of the eels body the signal would reach the primary cells in the stack prior to it reaching the cells at the end of the stack. By the time the cells at the end stack fired the cells at the beginning would have shut off again. Somehow the electric eel has to synchronize all the firing of the thousands of electrocytes in each stack so that they all turn on together and plus together to generate a large voltage needed to shock something. Three factors that are involved are:
- Nerve fibers are closer to the head of the eel and are smaller near to the tail of the eel.
- Slower chemical signals are implemented in nerve fibers closer to the head.
- Nerves that are closer to the head of the eel tend to take more winding path than the nerves that are nearer to the tail.
These factors said basically are to slow the nerve signals that are nearer to the head and speed the ones nearer to the tail. This equalizes arrival of the signal and makes all the electrocytes in each stack fire at the same time.
Compared To A Biological Lemon Cell
We will be investigating the emf of a lemon cell which is similar and can be compared to an electroplaque in other words an electrocytes.
To start the experiment we will insert two different metallic objects which are copper-coin and a zinc coated nail. The copper coin will basically be the positive electrode or cathode and the zinc coated nail would be the electron producing negative electrode or anode. Both of these would act as an electrode causing a reaction to generate a small potential difference.
The energy for the battery doesn’t actually come from inside the biological lemon but comes from the chemical change in the zinc. The zinc is oxidized inside of the lemon which makes it exchange some of its electrons so that it can reach a lower energy state, and the energy that is released provides the power. The lemon is merely the environment in which this can happen. But the reason why a lemon is used is because of its high acidity .
Links
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Salters Horners Advanced Physics For Edexcel AS Physics (Published In 2008) = Page 200 – Date Visited - 7th March 2010 - Pearson
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= Date Visited - 7th March 2010 – Submitted By Leland P
- Date Visited - 7th March 2010