Courtesy of Mother Nature Series: The Blind mole-rat and magnetic navigation

06 Aug 2023

It spends its entire life underground in its tunnels and burrows. Their eyes atrophied during evolution and are covered with skin, which is why the species got the name blind mole-rat.

This interesting creature doesn’t like company and interaction with other individuals and is very good at orienting in complete darkness. It lives much longer than other rodents and its marked resistance to tumors is still being tested.

Magnetic navigation

The survival and reproduction of a species largely depends on spatial orientation and the ability to locate food, a partner, a path to escape from danger, as well as awareness of the locations of neighboring individuals of the same or other species.

Surface-dwelling animals have a complex environment around them that provides plenty of cues for orientation. These can be some well-known landmarks on Earth or the Sun and stars that, for example, are used by some types of birds for orientation.

Compared to them, mammals living in the ground where the number of sensory stimuli is extremely limited had to develop special sensors for orientation and survival. Of all the underground rodents, the blind mole-rat went the farthest and most extreme in this discipline.

This species never leaves the ground unless forced to do so. The tunnel system in which it lives is closed and there are no above-ground exits. The stunted eyes only react to the stimulus of light and allow them to register when the earth they dig up during the construction of the tunnel is brought to the surface. Hearing is also weakly sensitive as in other subterranean mammals.

However, despite these serious limitations when it comes to the senses, the species has an excellent spatial orientation ability both in captivity and in nature.

A paper published by Israeli researchers in Tel Aviv in 2001 confirmed the previous hypothesis that this species uses signals from the Earth’s magnetic field for spatial orientation.

To clarify, the Earth is one giant magnet that has two poles, north and south. The planet’s core, which is in a liquid state, creates a magnetic field during rotation. Man made a needle out of magnetized metal, which was mounted on a shaft in some liquid (usually some kind of mineral oil) so that it could spin freely.

The needle can then detect the Earth’s magnetic field and turn north, and this is how the classic compass works.

Well, although it is not known how, the blind mole rat has this special feature installed by birth, special compliments from Mother Nature herself! 

The experiment

This team of scientists has created a device that will simulate the same strength of the Earth’s magnetic field, but with reversed poles.

As a replica of the blind mole-rat’s place of residence, a labyrinth was created, which has a central space in the middle, from which eight tunnels lead, and at the end of each there is a room.

The width of the tunnel is designed as in nature, in accordance with the width of the animal’s body. Food (carrots and balls for rats), material for making nests was put inside and they were left for two days to “coop up” and organize.

The blind mole-rats are divided into three groups.

The first group moved freely under the influence of the Earth’s natural magnetic field.

The second group included a device for changing the poles of the magnetic field, and the third group was first tested with a natural and then with an artificially induced field.

The first group clearly chose the south side for storing food and building their nest (each animal was in its own separate maze).

The second group predominantly chose the north side due to the change of magnetic poles.

In the first variant (with natural poles), the third group did the same as the first group, and after the polarity change, the same as the second group.

In addition to the layout of the rooms, a test of placing a reward, a piece of apple in one part of the tunnel and tests under normal circumstances and with reversed poles was also done.

The first group performed much better in finding the reward than the second group, which was clearly disoriented.

It was noticed that the blind dog uses only one room for sleeping and staying, that is, the shelter from which it can escape the easiest and fastest in case of danger.

Also, all food is stored in one room and therefore it is very important that an animal, from any part of its territory, knows where these two most important rooms are located.

Stay tuned for the next blog posts to learn more about this phenomenal creature and other unusual animals equipped with supernatural powers!