Researchers from the Hebrew University of Jerusalem have documented for the first time the coordinated circular movement of thousands of terrestrial isopods of the species Armadillo sordidus. According to the study, the phenomenon is caused by artificial lighting at night, and not by breeding or magnetic attraction.
Thousands of land snails, small crustaceans rather than insects, have been observed in Israel in recent years moving together in tight circles around light sources at night. A new study by researchers at the Hebrew University of Jerusalem, published in the journal Ecology and Evolution, describes the phenomenon as the first official scientific record of collective circular movement in terrestrial isopods.
The study was conducted on the species Armadillo sordidus. The study was led by Idan Shizaf and Aviatar Itzkowitz, under the supervision of Prof. Ariel D. Chipman from the Hebrew University. The phenomenon was identified in several sites in northern Israel, including the Golan Heights and the Jezreel Valley. According to the researchers, in one case, image analysis indicated about 5,500 individuals in one group, and in other observations, thousands and even tens of thousands of individuals were seen moving in a circular structure.
Not insects, but terrestrial crustaceans
Mussels are terrestrial relatives of crabs and shrimp. They usually live in moist, sheltered places, under rocks, leaves, or organic debris, to avoid drying out. That's precisely why the observations surprised the researchers: Instead of staying in hiding places, thousands of individuals came out at night and joined in a dense, coordinated, circular movement around a lit area.
The phenomenon was discovered by chance, after Eviatar Itzkowitz, a nature enthusiast from Kibbutz Geshur, noticed masses of mosses moving in circles on summer nights in the Golan Heights. The phenomenon was later examined more systematically, through observations, photography, image analysis, and field experiments. The researchers note that before the study, very little was known about the Armadillo sordidus species, and that the study also expanded knowledge about its distribution in Israel.
White light was the main factor
To understand what triggers the behavior, the researchers tested several possibilities. They examined whether magnetic fields might affect the movement, partly because the Golan Heights is known for its local magnetic properties. They also tested the response to ultraviolet light. However, these effects did not produce the circular motion. In contrast, artificial white light was able to induce the clustering and circular motion.
According to the study, when a beam of white light was projected perpendicular to the ground, the mosses moved to the center of the illuminated area and began to rotate around it. The researchers suggest that the shape of the light spot on the ground creates a circular boundary to which the individuals are attracted. When the density increases beyond a certain threshold, the individual movement of each individual becomes a continuous group movement.
Not a courtship ritual but a light trap
One of the main questions was whether this was a behavior related to reproduction. The researchers collected 102 individuals from the center of one of the clusters and found a ratio of 20 males to 82 females. Among the females, 24 were also found to be carrying eggs. This ratio, together with the nature of the movement, led the researchers to conclude that the phenomenon was probably not a courtship ritual or reproductive clustering, but rather a group response to crowding and artificial lighting.
The finding has broader ecological significance. Artificial lighting at night has been known for years to disrupt the behavior of nocturnal animals, especially flying insects. The new study expands the picture and shows that even small terrestrial creatures, which usually live on the ground and in moist shelters, may be trapped in an unusual behavioral pattern by street lighting. In one case, a raccoon was even recorded preying on individuals from the group, suggesting that the phenomenon may increase the risk of predation and waste vital energy.
The researchers emphasize that this is not just a natural curiosity. The observations show how a simple environmental change, such as installing strong lighting at night, can change ancient behavioral patterns of very small animals. The phenomenon of mosses moving in circles is not only an unusual sight, but a reminder that even a seemingly small, local disturbance can create a chain reaction in ecosystems.
The research article, titled “Light-induced novel collective circular motion in isopods of the species Armadillo sordidus", published inEcology and Evolution. .
Quick FAQ
What are isopods?
Isopods are arthropods related to crabs and shrimp. Some species live in the sea, and some live on land, often in moist, shady environments.
What caused the circular motion?
According to the study, vertical white light created a circular border of illumination on the ground. The isopods were attracted to this border, and as the density increased, a circular group movement was created.
Why might this phenomenon be harmful?
It takes the isopods out of moist, protected hiding places, exposing them to predators and potentially causing them to waste energy while they are caught in repeated movement.
More of the topic in Hayadan:
4 תגובות
I wish it was just a regular street light. The establishment bastards installed 5G receivers and sensors that are melting our brains. Another article with no point like your wounded life. Sit quietly.
A fascinating discovery, now all that remains is to investigate what this does to humans?
It's not just people who lose it and behave in a disgraceful manner.
Good morning Jerusalem
The effect of white light is made up of blue light waves that are harmful only to insects and animals. Understand that it is harmful to humans because after sunset, red and infrared light allows the secretion of melatonin. A powerful hormone that puts us into restorative sleep. Blue light secretes stress hormones and disrupts the secretion of melatonin - cancer, autoimmune diseases, inflammation and premature death. Reminds me of the labels on packs of tobacco and its products. From now on, put a label on every streetlight with white light!
Man is the most malicious pest on earth. Thank you for an enlightening and fascinating article.