Dung Beetles Orient By Taking Snapshots Of Celestial Scenery
While performing a dance on top of its ball, a dung beetle will store a single snapshot of the celestial scenery in its brain. By gathering information about how the Sun and other cues are positioned, the beetle can then roll its ball of dung in a straight line for a few minutes across the savannah, according to findings published in Current Biology this week.
To protect their nutritious balls of food from would-be rivals, dung beetles detach a piece of poop from the dung pile, fashion it into a ball, and then roll it away along a straight-line path. Previous work revealed that they rely on celestial compass cues to maintain their bearing. But how they read and use this information for orientation remains a bit of a mystery.
The team measured the change in direction between two consecutive rolls made by the same beetle. This allowed them to determine whether its bearing was impacted by changes made to the simulated scenery before the second roll.
They found that dung beetles dont rely on some innate prediction of how celestial cues are supposed to relate to each other position-wise (as other navigating insects seem to do). Instead, they form an internal representation of the celestial scene regardless of how unnaturally aligned or unrealistically distributed the objects are. The researchers call this a “celestial snapshot,” and the beetles take the snapshot during whats known as their dance: The beetle climbs on top of its ball and rotates about its vertical axis shortly before ball-rolling. You can watch cool little videos of dung beetles performing the dance here and here. Then, as they roll their ball, the beetles attempt to match the stored image it has of whatever was in the sky.
“Other animals and insects also use the position of celestial bodies to navigate, but the dung beetles are unique they are the only ones to take a snapshot where they gather information about how various celestial bodies, such as the Sun, Moon and stars, are positioned,” el Jundi said in a statement. Ants, for example, have been known to take snapshots, but of their surroundings, not the sky.
Image in the text: Close-up of a dung beetle. Lund University
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