When you and I have no idea where we’re going, we just hop in the car, fire up the GPS system, and tell it where we want to go. It does all the legwork and then we just do what it says to arrive at our destination safely, no matter how far away it might be.
According to a study published in the journal Current Biology, European eels might have a similar dependence on navigation systems. While they don’t have computerized GPS units like we do, they may actually rely on the Earth’s magnetic field to stay on track for their destination.
Image Credit: Nathan F. Putman et al.
When migrating, eels in our oceans will often travel thousands of miles to get to and from Europe from their breeding grounds in the Sargasso Sea. It was long thought that eels hitch a ride in the gulf stream, allowing the current to take them where they need to go, but new evidence suggests that they might be more self-driven than that.
By utilizing the Earth’s magnetic field to determine where they are on the planet, they can make adjustments to get on track for their destination during the long journey. After all, the influence of the magnetic field gets stronger as you move closer to the Earth’s poles, so feeling that difference can indicate where you are on the planet in terms of proximity to the equator.
While humans aren’t particularly sensitive to the Earth’s magnetic field, science has shown that various animals have a sixth sense for detecting magnetic fields, and eels just happen to be joining that list.
To help prove the point, NOAA researcher Nathan Putman and his team studied the effects of magnetic fields on juvenile eels and found that magnetic fields do influence the way that the eels swim.
They did this by subjecting the creatures inside of man-made enclosures to man-made magnetic fields that mimicked what they would expect to sense on their journey to Europe, and as they tweaked the magnetic field, they noticed the eels started to swim in a slightly different direction that matched the amount of give applied to the magnetic field, which began to show a trend in their actions. You might call these eels organic compasses, changing direction to match the magnetic pull.
The results indicate that eels have the innate ability to sense magnetic fields and may use it to guide themselves to their migratory destination, much like we would use GPS to get to our destination. Moreover, as the magnetic field changes, eels adjust their route accordingly, just as a GPS would re-route our route as we passed streets, roads became closed, etc…
The study isn’t without its fair share of nay-sayers however, as the use of juvenile eels is reportedly kicking up some debate. Their argument is that older eels should have been used in the experiments, as older eels have a more experienced sense of direction. The other side of the argument is how this is an innate ability and age really shouldn’t matter all that much.
Regardless of age, it would seem that magnetic fields do influence eels’ sense of direction, but perhaps further study into how magnetic fields impact eels of different ages could help quell some of the disagreement.
Source: Science News, Popular Science