Full Title: A Snapshot-Based Mechanism for Celestial Orientation
Abstract: In order to protect their food from competitors, ball-rolling dung beetles detach a piece of dung from a pile, shape it into a ball, and roll it away along a straight path . They appear to rely exclusively on celestial compass cues to maintain their bearing [2, 3, 4, 5, 6, 7, 8], but the mechanism that enables them to use these cues for orientation remains unknown. Here, we describe the orientation strategy that allows dung beetles to use celestial cues in a dynamic fashion. We tested the underlying orientation mechanism by presenting beetles with a combination of simulated celestial cues (sun, polarized light, and spectral cues). We show that these animals do not rely on an innate prediction of the natural geographical relationship between celestial cues, as other navigating insects seem to [9, 10]. Instead, they appear to form an internal representation of the prevailing celestial scene, a “celestial snapshot,” even if that scene represents a physical impossibility for the real sky. We also find that the beetles are able to maintain their bearing with respect to the presented cues only if the cues are visible when the snapshot is taken. This happens during the “dance,” a behavior in which the beetle climbs on top of its ball and rotates about its vertical axis . This strategy for reading celestial signals is a simple but efficient mechanism for straight-line orientation.
Hat tip to @GeneticJen
“Zoo animals that had met their demise lived on as their bills, horns, and antlers were shipped to Ted’s New York apartment to become exotic beaks and headdresses on his bizarre taxidermy sculptures. The result was an astounding 17 sculptures—created during the 1930s—which remain today as some of the finest examples of his inventive and multidimensional creativity.”
Makes me calm just watching this…
“This stunningly beautiful jellyfish was seen during Dive 4 of the 2016 Deepwater Exploration of the Marianas expedition on April 24, 2016, while exploring the informally named “Enigma Seamount” at a depth of ~3,700 meters.
Scientists identified this hydromedusa as belonging to the genus Crossota. Note the two sets of tentacles — short and long. At the beginning of the video, you’ll see that the long tentacles are even and extended outward and the bell is motionless. This suggests an ambush predation mode. Within the bell, the radial canals in red are connecting points for what looks like the gonads in bright yellow.”
Text and video via the NOAA Office of Ocean Exploration and Research, 2016 Deepwater Exploration of the Marianas.
And definitely worth the wait (for it to upload).
By Rafael B. Varona.
This is really nicely done*
Crash Course Big History episode with John Green, Hank Green, and Emily Graslie (link).
* I caught one small error during the lifting weights bit.