Butterflies Use Geomagnetic Compass

Butterflies Using Geomagnetic Compass. Scientists say the monarch butterfly, a migratory butterfly species, can navigate thousands of kilometers across North America using an internal magnetic 'compass'.

Monarch butterflies were known to fly using the sun as a compass. But the butterflies manage to fly south, towards Mexico, even on cloudy days.

Scientists trying to figure out how this could happen have revealed in a laboratory experiment that monarch butterflies change direction when the magnetic field around them is changed.

The research, published in the journal Nature Communications, argues that these findings reveal that insects, like turtles and birds, use geomagnetic compass.

The findings of the research have raised concerns that magnetic pollution created by humans may disturb butterflies. It is known that this man-made pollution can disturb robins, which are currently a migratory bird species.

miraculous migration
The North American monarch butterfly Danaus plexippus is known for its epic journey from Canada to Mexico.

Each fall, millions of butterflies that have not flown more than a few hundred meters before depart from Lake Erie and fly south to arrive in the warmer forests of the Mihoacan mountains.

The butterflies that spend the winter by covering the trees in these forests create magnificent images that attract thousands of tourists.

The Mayans, an ancient people, believed that these butterflies were the spirit of death. Butterflies have become symbols of trade and cooperation in North America.

Professor Steven Reppert of the University of Massachusetts Medical School said: “(Butterflies) have amazing biology. “They are inspiring and can teach us a lot about migratory animals.”

For years, Reppert and his team have studied how butterflies navigate along the equator.

They previously discovered that these animals were able to calculate the sun's position using light-sensitive molecules in their antennae.

When insects combine this with their internal biological clock, they have a timed solar compass.

But these insects, which do not lose their way even under thick layers of clouds, suggest the existence of an additional magnetic compass.

To test this, the scientists put the butterflies in a flight simulator and hooked them up, giving them directions as they flew "over the same spot."

Surrounding the simulator with a magnetic coil system, the team made it possible to change the position of the equator and the poles without changing the slope of the field.

The butterflies turned in the direction they perceived as south.

blue wave light
The critical point here is that the magnetic compass can only work when butterflies are exposed to ultraviolet-A/blue wave light. This has not been the case in previous magnetic field experiments with monarch butterflies, which explains why this type of compass has not been discovered in past research, according to the researchers.

"From what we know so far, this is the first time we've seen the use of an inclined magnetic compass by a long-distance migratory insect," Reppert says.

“In conditions where linear daylight beams are not available, this can act as an important navigation mechanism.”

Whether monarch butterflies have a "map sense" that enables them to recognize certain areas, such as where they may overwinter, is the subject of further research.

Researchers are trying to uncover the mechanism of this compass. According to them, the compass can work thanks to molecules known as "cryptochromes" located in the antennae of butterflies, which are sensitive to both light and magnetic fields.

A similar compass may be found in birds and sea turtles. But butterflies are easier to study and can provide clues about their behavior.

Reppert says that as many as half a billion butterflies can be seen in the wintering zone, but twice as few butterflies were observed last year, noting one concern: "The possibility of human-made magnetic pollution disrupting the butterfly compass."

Talking about a new study on robin birds, Reppert says that it has been shown that even weak magnetic fields from electrical devices and AM radios damage the internal compasses of birds.



Source : timeturk

📩 27/06/2014 09:34

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