Dung Beetles Use Milky Way for Night Navigation

Among the greatest findings in the expansive field of animal intelligence are those of the tiniest beings. Recent studies point to a revolutionary biological discovery: dung beetle (Scarabaeus satyrus) has been found as the first animal to guide itself according to the Milky Way at night.

The discovery has important implications on the role played by celestial bodies in shaping life on earth as well as highlighting the advanced evolutionary mechanisms that insects have employed to survive.

Significance of Direct Course

In the case of a dung beetle, straight movement is not only a preference but a necessity to survive. Dung beetles feed and reproduce on animal feces. When a beetle finds a new pile of dung, it soon breaks off a piece of it and rolls it away into a ball.

The most dangerous threat is other beetles, which tend to steal an already made ball instead of making their own. This competition requires the beetle to leave the dung pile as fast as possible to prevent this competition. The most effective method to make sure that they do not go back into the danger zone accidentally or even use valuable energy is to use a straight path.

Daytime vs. Night-time Strategies

Dung beetles are proficient in celestial orientation: at various times of the day, they use various light sources:

• Daytime Navigation: Beetles use the Sun in the day. Humans perceive only bright light, but dung beetles are able to perceive polarized light patterns in the sky that are used as a compass to ensure they stay in the same direction.

• Night Disinhibitions: During the night, there is no polarized sunlight. Although there are species that utilize the Moon, it is frequently missing or covered by clouds. Scientists discovered that during moonless nights nocturnal beetles such as Scarabaeus satyrus were still able to keep straight courses.

Milky Way Role

To learn the mechanism of the movement of these insects in the dark, the researchers did the experiments in an open field and in a controlled planetarium. The findings were shocking: the beetles did not see the separate stars, but the smear of light produced by the Milky Way galaxy.

The beetles still moved precisely when scientists restricted the visual field to the bright streak of our galaxy. To further affirm this, scientists put a small cap on the heads of the beetles to cover their eyes to the sky. 

The beetles had no way to know where to go, not seeing the stars or the Milky Way, and wandered around in random circles, which proved that their inner compass is directly related to the night sky.

Implication on Science and Conservation

The finding puts the dung beetle in an elite group of navigators. Although numerous birds and humans rely on certain stars to navigate, it is a special biological feature to have a complete galaxy as a regulatory signal.

In addition to pure biology, this study highlights the increasing menace of light pollution. With the Milky Way being obscured by artificial light in the cities, nocturnal navigators such as the dung beetle might not be able to survive, thus throwing the ecological balance that they are capable of creating due to fertilizing the soil and clearing the waste.