Maybe you know the name, but do you know the fascinating story of George Washington Carver?
by Ana Wang, Graduate Student at The Scripps Research Institute
It’s that time of year when we can’t walk into a store without seeing displays of chocolate bunnies, marshmallow chicks, and vibrant bouquets of flowers. Along with all these springtime treats, perhaps the most memorable and engaging tradition (and my personal favorite) is the dyeing of Easter eggs.
Decorating eggs is a deeply rooted, international tradition. The oldest examples of this activity are the engraved ostrich eggs found in Africa 60,000 years ago. Eggs across many countries and cultures are celebrated, and whether these activities are based on religion or the coming of spring, eggs represent rebirth and life.
For those who have participated in egg dyeing, you may have wondered: Why is vinegar added to the dye solution? This can be explained through simple chemistry. You've probably heard of acids and bases - it turns out that all solutions have a degree of acidity or basicity. Acids chemically react with bases to create solutions that are more neutral – that is, closer to pure water.
So, back to the initial question – why is vinegar needed to dye an egg? The answer is that most egg dyes need acid to bind the dye to the eggshell.* Vinegar is an acid, and eggshells are bound together by a basic molecule called calcium carbonate. The eggshells base molecules assure that neutral and basic solutions will not change the eggshell. However, vinegar will react with the calcium carbonate shell to dissolve it slightly, allowing the dye molecules to stick to the eggshell, giving you vibrantly colored eggs.* Without adding vinegar to your dye solution, you will likely get very faint coloring.
Have you ever tried changing the amount of vinegar added to your dye solution? Because acid is needed for the dye molecule to stick to the egg, you might predict that adding more vinegar to the solution will give you more colorful eggs. This may be true to an extent, but be careful! The acid reacts with calcium carbonate to produce carbon dioxide gas, which will float out of the solution, like carbonation in soda. This gas forming on the surface of the eggshell can leave behind streaks, causing a blotchy dye job. That is why there is an optimal amount of vinegar recommended for the dye solution. Too much vinegar or leaving the egg in the solution too long will eventually dissolve the eggshell. For a neat science experiment exploring this, click here ; you can also find this experiment in Dr. Olivia Mullins' book here!
Have you ever seen someone dye eggs with a silk tie? (If not, watch this clip from Martha Stewart!) The patterns on a silk tie can be transferred from the tie onto the egg by wrapping the egg in the tie and submerging it in water with vinegar. Eventually, some of the dye from the tie will be transferred to the eggshell. This is because silk ties are usually dyed using dyes that require an acid to bind – the same reason that dyeing eggs requires vinegar. By adding vinegar to the water, the tie’s dye molecules can be transferred over to the eggshell.
Now that you know the chemical principles behind this tradition in addition to some tips and tricks for optimal coloring, there is no reason for not making this Easter your most colorful yet.
*Going further: Egg dye molecules are typically sodium salts of a negatively charged molecule called a phenolic acid. In an acidic solution, it gains a H+, allowing it to interact with the surface of the eggshell. In particular, dye molecules interact with slightly negative parts of the eggshell, including the calcium carbonate and some parts of proteins.
Other fun egg experiments
· “Silky Science: Tie-Dyeing Eggs.” Scientific American. 21 March 2013. https://www.scientificamerican.com/article/bring-science-home-silk-egg-dyeing/. 26 March 2017.
· Stewart, Brian. “Egg Cetera #6: Hunting for the world’s oldest decorated eggs.” University of Cambridge. 10 April 2010. http://www.cam.ac.uk/research/news/egg-cetera-6-hunting-for-the-worlds-oldest-decorated-eggs . 26 March 2017.
Bunny and eggs: Superbass, CC BY-SA 4.0, via wikimedia commons
Basket of Bulgarian Orthodox Easter Eggs: lkonact via wikimedia commons
Egg in Vinegar: Yat-Long Poon, in Experimenting with Science, Wiley Publishing
by Ana Wang, Graduate Student at The Scripps Research Institute
With St. Patrick’s Day around the corner and a tumultuous start to 2017, most of us probably hope for a little of that fabled Luck o’ the Irish, and what’s more hopeful this time of year than finding a four-leaf clover? The myth of the four-leaf clover bringing good fortune has cultural origins that may be as simple as the fact that these clovers are rare, so finding one can make you feel special – or lucky. And they are pretty uncommon – on average, you’d have to search through 10,000 clovers to find one four-leaf clover! More rare still are clovers with five, six, seven, or more leaves – but they do exist. Currently, the world record is at 56 leaves on a clover found in Japan!
Have you ever wondered why some clovers have four (or more) leaves? Or maybe you’ve wondered why more clovers don’t have four leaves. Well, look no further as we are going to delve into the science behind this lucky charm.
Whether or not a clover has the fortuitous fourth leaf – (or, more accurately leaflet) – is largely based on the code in the clover’s genetic material. That being said, the exact cause of the fourth leaflet is hard to study and largely unknown, due to some quirks of the clover’s DNA. The common clover in North America is the white clover* which has four copies of each gene.** For reference, humans and most other organisms only have two copies of each gene. To add to the white clover’s genetic complexity, each chromosome (which contains the genes) in an individual clover often comes from a different species. You can imagine how hard it is to study lineage and inheritance with essentially four different parents!
It is hypothesized that many genes, rather than a single gene, contribute to the determination of whether a clover is a trifoliate (three leaflets) or multifoliate (more than three leaflets). The Parrott Lab at the University of Georgia shed some light on this issue by studying three-leaf and four-or-more-leaf clovers in separate, but identical, surroundings. This set-up allowed the researchers to zero in on differences that stemmed from only genetics, as it kept the environmental influences of the two groups the same. Studying the DNA from the clovers showed that the multifoliate trait is recessive to the trifoliate trait. This means that even when a clover contains genes for both traits, it will have a trifoliate morphology. This is predominantly why the multifoliate variants are much more rare than the traditional three-leaf shamrock.
Genes are not the end of the four-leaf-clover story, however. The Parrott Lab also did some work on environmental influences. They ran their studies in both summer and winter and found more four-leaf clovers grew in the summertime, showing that genes AND the environment influence the number of leaves on a clover. Many suspect that chemicals and radiation may also increase the occurrence of four-or-more leaf clovers – but that has yet to be proven.
The four-leaf clover has become an international symbol of good luck. It is said that St. Patrick used the shamrock – the clover symbol of Ireland - to explain the Holy Trinity, with each leaflet representing one hypostasis . It is also said that the three leaflets represent hope, faith, and love. To many today, the fourth leaflet on a four-leaf-clover represents luck. To many in the Middle Ages, it was believed to bestow the carrier with the magical power to see fairies. To plant biologists, though, it can represent the amazing complexity and infinite possibilities that lie within even a seemingly simple and common weed.
*The scientific name for the white clover is Trifolium repens, where trifolium refers to three leaves.
**Organisms with four copies of each gene are called allotetrapoloids.
· “Most Leaves on a clover.” Guinness World Records. Web. 15 March, 2017.
· Tashiro, Rebecca M., et al. Leaf Trait Coloration in White Clover and Molecular Mapping of the Red Midrib and Leaflet Number Traits. Crop Science 50, 1260-1268 (2010).
Many clovers: By JPS68via Wikimedia Commons
Four-leaf clover: By Calignano via Wikimedia Commons
Five-leaf clover: By 本人 - 本人, via Wikimedia Commons
Three-leaf Shamrock: via Wikimedia Commons
Did you know Marie Curie had a daughter, Irene Joliot-Curie who won a Noble Prize in Chemistry? Get a run down of some of the early women pioneers in STEM in this Esoterica podcast! We are happy to say that Science Delivered gets a shout-out at the end. It's a short program so we highly recommend listening to the whole thing, but if you MUST skip ahead our piece starts around 2:47.
Thanks to Chris Kenna and Esoterica for this great piece!
*Esoterica is weekly radio program in Maine.
Science Delivered founder "Dr. Olivia" has authored her first book! "Experimenting with Science" is published by Wiley and the For Dummies people. It's part of a new Dummies series for kids, aimed at ages 7-11, but we think grown-ups can enjoy it too.
Inside you'll find some of our favorite experiments! All experiments are done with simple and mostly household materials. We take on: Forces, Air Pressure, Sound, Chemistry, Plants and Animals, Perception and Art and Science. Check out the bonus material too!
Time for Credits! Our models were Teke Helms and Annika and Avery Pitts. Sam Poon did much of the photography work. Cynthia Mullins did several of the art and science experiments and inspiration for using recycled materials for Magnet Monsters can from Erin Pennell from ArtFORM. Paul Bonthius and Charles Toth did the technical editing, and Oliver Mullins helped with some Chemistry. Stephanie Mullins helped edit some of the "layman" pictures we had. Thanks everybody for your great efforts!
Here at Science Delivered an important part of our mission is promoting confidence and critical thinking. Kids and adults possessing these attributes are well prepared to pursue their goals and navigate life’s obstacles. But while the words ‘critical thinking” gets thrown around quite a bit, we rarely see a critical analysis of the term itself. So what does 'critical thinking' really mean?
The dictionary definition is:
"The objective analysis and evaluation of an issue in order to form a judgment.”
But this definition isn’t overly helpful. So, in order to define this skill that we aim to cultivate, we’ve come up with 14 of our own definitions. Here it goes!
What does 'critical thinking' really mean?
Critical thinking means being willing to change your position or beliefs as you collect more data.
Critical thinking means being open to (quality) data that contradicts your previous beliefs.
Critical thinking can mean ignoring an emotional or “gut” reaction to new information; our guts can make mistakes!
Critical thinking means taking into account the source of the information.
BUT critical thinking also means never (or rarely) dismissing information out of hand simply because of the source.
Critical thinking means understanding that presented facts can be technically true but the manner in which they are presented can be skewed or misleading.
Critical thinking means understanding that people, companies, ads and politicians often rely on authoritative sounding “science” and “statistics” to change your beliefs or behavior. Sometimes the facts they present are legitimate, but often they are not. Learning how to tell the difference makes navigating the world easier.
Critical thinking means viscerally understanding that you don’t know everything.
Critical thinking means resisting believing things solely because they fit in with your worldview.
Critical thinking means understanding that others have had truly different experiences than you and may have different values and expectations of the world. This doesn’t (usually) mean one person’s values are right and another’s are wrong.
We can’t be experts on everything, so we have to trust experts to inform our beliefs and ideas. But experts are not infallible – they can be wrong! In our opinion critical thinking means trusting the experts around 80-85% of the time.
Critical thinking means being skeptical, especially when things seem somewhat unbelievable, but not being dismissive out of hand of new ideas.
Critical thinking is often described as removing emotion from your ideas and decisions, but we only partially agree with that. Sometimes emotions and empathy are needed for sound critical thinking.
Critical thinking means knowing that just because you have believed something all your life, doesn’t necessarily mean it’s true! Sometimes beliefs and ideas need to be reevaluated as we grow.
Teaching and engaging in critical thinking is helpful for the individual student and helpful for society. Critical thinking helps counteract bias and lets us evaluate what our biggest needs are and where our energy is best spent. We hope we can help our students obtain these lofty goals!
We’d love to hear from you – is there a definition of critical thinking that you'd like to add to our list?
Move like crazy - or sink!
Recently at Science Delivered, we created an Oobleck Pool. Never heard of this before? Watch the video below and see if you see anything unexpected.
wHAT'S GOING ON?
"Oobleck" is the popular name given to a corn starch and water mixture. This mixture has the fascinating property of being a solid or a liquid depending on the pressure, or shearing force, exerted upon it. More on this down below, but in practical terms, it means that smacking the Oobleck Pool with your feet temporarily turns the surface into solid. But if you place you feet (or hands, or elbow etc) into the Oobleck slowly, you'll get sucked right in.
Where does the name "Oobleck" come from?
The term "Oobleck" comes from an early work of Dr. Seuss, Bartholomew and the Oobleck. Magicians make a green gooey substance come down from the sky; it creates havoc in the land and look quite similar to the cornstarch and water mixture when you play with small amounts of it and let it drip. Our Oobleck can create havoc too - if you get stuck in it!
What is a non-Newtonian Fluid?
This might be best answered by defining a "Newtonian" fluid, which is an ideal liquid. In lay terms, the flow of a Newtonian fluid will not change no matter what you do (assuming constant temperature). If you consider water, you can pour water our slowly, or stir it really fast, or shake it up in a bottle and flows remains the same in all conditions. The viscosity does not change.
In contrast, consider trying to get ketchup out of a glass bottle. The ketchup will sit, clumped, requiring you to bang the bottle to get it out . . . at which point it would all come out at once. The applied force (hitting the bottle) causes the viscosity of the ketchup to change. The Oobleck is a mixture of corn starch and water. When you apply force to this mixture, the mixture hardens, enough so that you can walk on a pool of it. But if the force is too weak, the substance will act as a liquid and you will sink right in.
Are all non-newtonian fluids the same?
No! Non-Newtonian fluids can be classified as shear-thinning or shear-thickening. Meaning, fluids can either decrease or increase their viscosity in response to force. Remember how the ketchup flowed quickly out of the bottle once you hit it? That means it is sheer-thinning, it flows more easily in response to force. Other shear-thinning fluids are paint, blood, whipped cream and lava. The Oobleck corn starch and water mixture, on the other hand, is shear-thickening. This mixture becomes a solid with increased force, and acts as a liquid otherwise, as you can see from the video above and this one here.
It is interesting to note that the Oobleck is often compared to quicksand, however, according to this article, quicksand is shear thinning, and therefore behaves in an opposing manner to the Oobleck. In quicksand, it is the force of walking on it that liquifies the substance, which is why frantic struggling will only get you deeper. See the powerful effects of quicksand, and how to escape here.
So How do you make an oobleck pool?
Oobleck is easy to make in small quantities - just add a cup of water to ~ 3/4 cups of cornstarch and kneading it with your hands until the cornstarch is mixed in and not clumpy. More detailed instructions can be found here or here.
Making a pool is a whole other story. It's messy and expensive, and a difficult clean up, but if you are really hankering to do it we will give you instructions!
You will need:
200 pounds corn starch (can be modified for different size pools)
20 gallons of water
Tarp to protect the ground
~15 heavy duty trashbags for disposal.
We started by using this kiddie pool and finding a wholesale food company who generously allowed us to open an account even though we wouldn't be making regular purchases. 500 pounds of cornstarch delivery later and we were ready to go! You can order large quantities of corn starch off Amazon, although it's not cheap.
We then rented a cement mixer. Do not even attempt to mix this by hand! Ours fit one 50 pound bag of cornstarch at a time. We used roughly 5 gallons of water for every 50 pound bag. Even with the cement mixture we would get clumps of unmixed cornstarch stuck to the sides and have to scrape them off. Test the mixture with your hands, if you move your hand slowly through the material (with the mixer off of course) it should be relatively clump free.
We ended up getting a pretty decent pool with "only" 200 pounds of cornstarch, so it took four cycles in the cement mixture. I'd recommend leaving at least an hour for set up assuming you have several strong adults.
If the pool is left untouched for a few hours the cornstarch will separate from the water and settle at the bottom - this pool is good for one-day use only.
Put down a tarp! This is an extremely messy project. The cornstarch billows everywhere and it does not come off the ground easily. The ground protection we used was inadequate and after several sweeping and hitting our patio with a hose there is still cornstarch stuck in cervices.
Disposal is another issue. We let the cornstarch sit for a couple days in an attempt to let it dry out, but it will start to rot so you can't let this go on for too long. We then double bagged heavy duty trash bags and picked it up in clumps into the bag. The trash can was extremely heavy but luckily the city still took it away.
There you have it! Everything you wanted to know about Oobleck Pools. For the unique chance to try this yourself, come to Science Fest 5K. [edit: Science Fest 5K has passed]
We talked to Kaitlin Roig-DeBellis, founder of a like-minded non-profit Classes 4 Classes, about empathy and compassion. We loved what she had to say! (Scroll down for interview). You can read our interview by Classes 4 Classes here.
What is Classes 4 Classes?
The beautiful thing about our world is that there are often infinite ways to tackle a problem. While Science Delivered is, of course, science focused, our ultimate goal is to promote positive outcomes to our students. That’s why many of our programs incorporate lessons about being good citizens. Our psychology and critical-thinking courses especially are designed to help students understand that those different from them also deserve respect and compassion. But children need to hear this message again and again and in multiple ways. A task bigger than any one company!
That’s why we were so excited to learn more about the non-profit organization Classes 4 Classes. Classes 4 Classes (C4C) has an awesome yet simple mission and that is to teach children the power of kindness, and that through compassion they have the power to enact positive change. They also teach about how we are all inter-connected. Should kids be learning this at home? Yes, of course, but recent research suggests that even in many well-meaning households the ideas of fairness and compassion are treated as less important than other qualities. And there is hard science to support the rather intuitive idea that compassion can be taught! While on the face of it C4C's goals are very different Science Delivered's, we found, at the core, there is actually a lot of overlap in our missions.
Kids need more than to be told to “be kind” they need chances to practice kindness and altruism. That’s where C4C comes in. Their free program is based on giving without the expectation of getting something back, a “pay it forward” model. After a classroom, say ‘Classroom A’, signs up to participate, their next step is to choose a recipient class, say ‘Classroom B’. Classroom A now takes the time to learn about ‘Classroom B’ and what this classroom needs. Once they find out what item (within reason) will help ‘Classroom B’ the most, ‘Classroom A’ chooses this as a gift and posts it online. Donors can now help fund the gift and ‘Classroom A’ gets to experience the joy of giving.
The fun part is that once ‘Classroom B’ receives a gift, they now pay it forward by choosing another class to research and pick out a gift for!
Classes 4 Classes started in Connecticut but has spread as far as Arizona and has been nationally recognized. You can read more about the organization at their website as well as news stories and accolades here, here, here and here. We talked to C4C founder Kaitlin Roig-DeBellis to find out more about her thoughts on C4C and its mission!
Q: We know that the mission of Classes 4 Classes is to increase empathy – what does empathy mean to you? Why is it important?
Kaitlin: Empathy to me is the ability to relate to and put yourself in the position of someone else, whether they are similar to or very different from yourself. It’s the ability to understand someone else's feelings and relate to what they are feeling on a personal level.
Teaching children empathy assures that they are aware of what makes us each different, as well as what unites us as one - and being accepting of both. Teaching empathy is crucial because we can't assume that our students come to school already aware of how to be empathetic towards others - they need the chance to have tangible experiences with it.
Q: How did you decide on the structure of C4C?
Kaitlin: When planning the structure of C4C, it was crucial that students would have an active role and actually be engaged in giving the gift to another class and ultimately in being kind, caring, compassionate and empathetic. I knew they had to be active in the process in order to learn these lessons. That's where the format for the individual project pages came from - a place to showcase the students' work [ed note: see here].
I also knew that funding the projects had to be crowd sourced because I didn't want any financial responsibility to fall on schools, teachers or students. I wanted to make sure that all students in all schools would be able to participate.
Lastly, I knew that it had to be a pay it 4ward model, because if the core of what we teach is giving back and connectedness (which it is) then we need to follow that model and encourage all students to give back!
Q: What’s one favorite story that has come out of a Classes 4 Classes event or classroom?
Kaitlin: There are so many! I think one that truly illustrates what we at C4C aim to inspire in students, is the story of two 4th grade classes who participated in C4C. The students had posted a project for another class to get iPads. Then those students did something truly amazing. They decided it wasn't enough to just wait for outside donors to fund their project. They wanted to do more! They asked their teachers if they could host a tag sale, where students who wanted to participate could bring in an item that they no longer used to sell. This was completely their idea. They spent all day on a Saturday hosting and working at their tag sale. They raised over $700 for their project! To me this illustrates exactly what C4C is working to engage students in-actively caring, being kind, compassionate and empathetic. Those students' actions illustrate all of these! I can't think of a better way to demonstrate empathy for others-than selling your own possessions to give a gift to someone else.
Q: What’s been your favorite part of your C4C journey?
Kaitlin: There have been so many favorite parts! I could never choose just one. It has been the journey, the daily ins and outs, the connections and spreading our mission. It's the teachers and students I've met with and interacted with. It's been watching the growth, how far we've come since February 2013. It's seeing the vision for our mission come to fruition. It's changing the way kindness and empathy are taught to students. It's all of the people and organizations who have supported and continue to support us. It's working with our incredible board on a day to day basis to spread our mission. It's been realizing that if you believe in something, in your vision for it, you can make it a reality.
Q: If someone wants to support C4C how can they get involved?
Kaitlin: Anyone can get involved! Simply visit http://www.classes4classes.org and click on 'Get Involved' there are lots of ideas whether you are a parent, teacher or potential supporter. There are also downloadable documents that you can use to share our mission with others. Our supporters can support our class projects, our mission directly or both! If you have specific questions you can email: email@example.com
On Monday January 26, an asteroid, 2004 BL86, came close enough to earth for us to see. To add to the excitement, this asteroid has its own moon. (NASA reports that they have found 150 asteroids with moons, or even double moons.)
Now, at 745,000 miles away, 3.1 times the distance to the moon, 2004 BL86 is not dangerously close. However, it got us curious about NASA’s Near Earth program, which closely tracks asteroids that enter Earth's "neighborhood" and can predict their path years in advance.
Perhaps some readers remember that in 2004 an asteroid named 99942 Apophis was evaluated as having a 2.7% chance of hitting earth in the year 2029. Refined measurements of it's movements showed that we were in the clear for 2029, but that a very small chance of impact remained for the year 2036. A 1 in 45,000 chance to be precise. Even with a 0.0022% chance of an asteroid hitting the earth, there was serious discussion about how to deal with this risk, which shows us that NASA takes it's job seriously. Then in 2013, it was announced that the chance of the asteroid hitting the earth in 2036 was effectively zero. But what if the risk had remained? What actions could be taken?
There have been several proposals for deflecting asteroids, and in this case the necessary deflection to keep us safe was deemed small. One study found a “130 x 130 ft. patch with a lightweight reflective surface" would change the energy absorption of Apophis by 0.5% which would be enough it influence it's trajectory so it would certainly bypass Earth, IF the procedure was done by the year 2018.
Another report had more extensive suggestions. (A side note: This report also estimated the potential damage of the asteroid hitting earth at 400 billion and the cost of a deflection mission at 400 million. It suggested the course of action be taken based on financial concerns and ignored the loss of human life and suffering (ahem)).
The first two suggestions of this proposal would need to be accomplished prior to the year 2029. This is because the year 2029 is where the 0.0022% danger comes from. We knew that in this year the asteroid would come relatively close to us and if asteroid came at exactly 18,893 miles from the earth it would fly through a "gravitational keyhole" which would alter its trajectory enough to set it on a course where it would hit the planet. To miss the keyhole, the asteroid would only need to be deflected about a mile. However, if it were to pass through the keyhole, it would be to be deflected 5000 miles. The latter obviously a much harder task, and would perhaps (but probably not) be impossible.
The first proposed method was “kinetic deflection” which would consist of hitting the asteroid with a large spacecraft to knock into a slightly new trajectory. That's it. Oh, of course there are angles, masses and speeds to work out but the basic concept is pretty simple.
The second method promoted in this report for pre-2029 use is the “gravitational tractor” which is much like what it sounds. Remember, all masses in space create a gravitational pull which effects other nearby masses. Here a rocket-propelled vehicle would essentially tow the asteroid onto a safer orbit through it's gravitational pull.
If the asteroid entered the keyhole in 2029, however, and was scheduled to hit earth, neither of the above methods would be powerful enough to keep us safe. In this case a more extreme courses of action would be needed such as "buried bombs" or nuclear weapons detonated near the planet. These are the methods NASA considers most viable for moving asteroids off course. However, bombs (as well as the kinetic deflection method) would send smaller pieces of the asteroid into orbit in an uncontrolled (by us) manner, and some of these could very well end up landing on Earth and still cause substantial destruction.
Other proposals have also floated around such using a laser or giant mirror to "boil" off part of the asteroid.
Luckily, Earth seems safe for quite a while. Jupiter, on the other hand, with its massive size and gravitational pull, has taken the hit from several asteroids and comets. We can be grateful to this large planet as it is thought to be, quite literally, taking hits for us.
Bill Nye has a nice simple video explaining these concepts if you'd like to check it out. If any of our readers have expertise in this area we'd love to hear from you!
Thanks for reading. Check out our facebook page for daily science news from around the web, and check back here for more original content and news about our company.
In a recent Science article, the mechanism electric eels use to incapacitate their prey was found to work via a mechanism surprisingly similar to Tasers.
First, some background. The electric eel is not a true eel, but an electric fish. (Eel themselves are a type of fish, but the electric eel is a different type of fish. Confusing! One difference that true eels have dorsal fins and electric eels do not).
A large portion of the electric eel's body is made of electric organs which contain flat disk-shaped cells called electrocytes. As their name suggest, these cells each produce a small voltage, about one-tenth of a volt. In total however, the electric organs can produce up to 600 V in certain species. The ability to discharge electrical shocks is the basis for their prey-hunting capabilities.
When the electric eel has its prey in range, it discharges a high-frequency volley of electric shocks. Do you imagine a animal jerking around from all the electricity? Don't! Turns out that the discharge frequency completely immobilizes the animal. Basically, the pulses come fast enough that they contract all the muscles in the prey's body, so it remains completely still, and the electric eel can attack. This is how Tasers work! However, the Tasers deliver about 19 pulses per second, while the electric eels discharge around 400 per second.
But how does the electric eel locate its food in the first place? It turns out that the discharge is under fine control. If the eel wants to locate potential near-by but hidden prey, it lets off two pulses, or doublets, that cause the prey animal to "jerk" or "jump". Now the hiding place of the prey animal has been compromised, and the electric eel can employ its high frequency discharge to attack.
To summarize: To locate hiding prey, the electric eel lets off two pulses that make the prey "jump." To immobilize said prey, the electric eel lets off a high frequency volley of electric shocks and then eats the still, floating, fish.
This work comes out of Vanderbilt from a fantastic researcher named Ken Catania (although at the time of this posting his website has not been updated to reflect the electric eel publication). I've had the honor of hearing him speak and his work is truly an original and creative exploration of animal behavior.
If you want to know more, this research has been reported all over the internet. Check out this video from Slate, or these reports from the NYT, BBC or National Geographic. You can find a link to the original research here, (click on the Science link on the right) but you need a Science subscription to access it.