Animalogy: Magnetite - How Animals Find their Way Around Our Planet using Earth’s Magnetic Field
What is the magnetic field?
Birds. butterflies, bats, turtles and many other animals roam the skies and float across the open waters of the globe, travelling thousands of miles to their destinations. These animals never stray off course, lose their direction, or end up in the wrong location.
The Earth’s magnetic field is what makes compasses point north. The Earth’s magnetic field protects our planet from much of the sun’s dangerous radiation. An English scientist in 1600 named William Gilbert suggested that planet Earth is a giant magnet. Earth became a giant magnet from the molten rock that flows within it. Molten rock is rich in magnetic products such as iron. Earth’s magnetic field reaches into outerspace. When the energy filled particles zoom in from the solar wind of the sun, it causes an interaction with Earth’s magnetic field. This is the explanation for the Northern lights, (Aurora Borealis), and the Southern lights (Aurora Australis) and perhaps the explanation for the strange lights that are seen before an earthquake.
Scientists know the Sun also has a magnetic field many times stronger than Earth’s. The moon is not magnetic, but the other planets are. Some planets have a weaker, and some planets have a stronger magnetic field than Earth.
Many Animals Rely on Earth's Magnetic Field to Get Where They Want to Go
Scientists have studied many species and have determined that these animals have a built in compass that guides them in the direction they need to go.
Monarch butterflies travel approximately 2,500 miles in their autumn migration from the Northern part of the Americas of Eastern United States and Canada to Mexico for their winter retreat. Because of the lifecycle of the butterfly, millions of them are going to a place they have never seen or been to before.
Some studies have shown that the Monarch butterfly orients itself according to the sun. There is growing evidence that Monarchs also get their sense of direction from the magnetic field. Experiments were done where these butterflies were caught and released into a tube upward. The room had no shields from Earth’s magnetic field and most of the butterflies flew in a southwest direction. Another group of butterflies were released in a room that had shielding from Earth’s magnetic field and when released, they flew in various directions randomly. Then researchers designed a room where the magnetic field was going in the opposite direction from Earth’s. When released the butterflies flew in the Northwest direction of Earth’s magnetic field, a southwest direction of the room.
Echolocation and Earth's Magnetic Field
It appears that animals use more thant one way to help orient themselves in the right direction. Night migrating birds have been noted to orient their direction by the sunset and patterns of the stars, in addition ot the magnetic field.
It is believed sea turtles, honeybees, bats, some species of fish and wasps, migratory birds, lobsters ,pidgeons,salamanders,and some moe rats have the ability to navigate via Earth’s magnetic field.
Science knows bats use echolocation for hunting prey in the dark, and know this ultrasound technique is effective for short distances. For long distances, scientists now believe bats may use the earth’s magnetic field also to help them navigate their way. Just like migratory birds experiments, bats tested, showed similar confusion when the magnetic field was changed under controlled circumstances. Scientists already knew bats used the setting sun as a direction marker. A team used the common species of large brown bats (Eptesicus fuscus) released them 12 miles from their home, attached with lightweight radio transmitters. Some bats were exposed to an artificial magnetic field going in the opposite direction at dusk. Some bats were not. All the bats were able to see the sunset. When the bats were released the bats who had the artificial magnetic field tried to fly home, but went in the opposite direction. The bats who were using the natural magnetic field flew in the correct direction and made it home. Later that night, some of the bats who flew the wrong way, found their way home. Scientists aren’t sure if they recalibrated their direction or used some other cues to navigate correctly. There also may be other innate directional systems that science is not yet aware of.
What the heck is Magnetite?
Biologists believe these animals are able to use the magnetic field because of magnetite, a magnetic mineral in their bodies. It is known there are 2 types of magnetic fields built in theses animals. The simple way these animals navigate is with the use of these magnetic particles. There are some birds that can sense changes in intensity in light caused by the Earth’s magnetic field. This second type of sense for direction is more sophisticated, and scientists know birds use this, but are not sure if bats have this type of sensory device. Only 10% of the bats in the world have been studied to date.
Homing Pigeons are known to be able to find their way home, even if they are thousands of miles away. Through testing, scientists now know without a doubt, that these birds use the Earth’s magnetic field. Pigeons have been used to carry messages far away and return home since ancient Egyptian times. Scientists think the pigeon’s magnetic receptor is in their beak. When scientists anesthesized the upper beak area, it cause impairment in their ability to detect magnetic fields. They now know the magnetite is located in the nasal part of the bird’s beak.
Magnetite crystals are made of magnetic properties like iron. Rainbow trout also has magnetite in their noses and these fish also use the magnetic field for direction.
Prior to the discovery of magnetite in these animals, researchers believed pigeons were able to use their homing ability through their sense of smell. Sea turtles are known to have magnetite too. The more scientists study magnetoreception, the more they are beginning to understand that magnetite is not only the factor in an animal’s ability to get where they they want to go. But biologists and scientists have yet to figure out which senses are involved in magnetoreception.
Magnetite was Found in Birds Beaks
What they are starting to understand is the magnetite in a bird’s beak may play a role in the strength of detecting the magnetic field around earth, but it may not be the factor that tells the direction to go. It is believed that even chickens may have this ability like other birds.
Sea turtles are one of the most accomplished navigators on the planet. They have been tracked by scientists, and known to travel thousands of miles across oceans to get to their destinations.
Scientists believe turtles may have a built in compass that gives them an ability to get a reading on their geographic position from subtle changes in the Earth’s magnetic field. It is thought they use a sophisticated built in system that helps them pinpoint the location where they are, in relation to their intended direction. It is the equivalent of of a biological GPS (global positioning system), using their magnetic system. Studies using spiny lobsters show they have a similar mapping sense to sea turtles.
Do Humans Possess Magnetite?
Even cows and deer are thought to have some built in magnetic direction signals. In a study done in Germany, it was found high voltage electrical power lines interfered with the cows and deer and dioriented the animals. When the power lines ran east and west, the cattle who were grazing lined up in an orderly way by themselves. The cows and deer faced in random directions when they were grazing under northeast and southwest power lines. Since power lines produce a magnetic field the study shows this could be causing some interference and confusion among the animals.
Do humans have magnetite?
Scientists from the California Institute of Technology discovered a small crystal of magnetite in bone between our eyes, just behind our nose.
This could have helped early man’s evolution in migration and hunting. But there is not much evidence supporting this.
Magnetite is present on Earth and in many animals. It appears to be one of the factors in enabling many migratory animals to head in the right direction. As far as us humans, it seems so many of us are lost, we may be lacking in magnetite and other directional tools to help head us in the right direction. We have GPS systems on the road, but what about in life? It looks like we don’t have much magnetoreception, so we are on our own.