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For over a century, thousands of poisonous centipedes have invaded the railroad tracks in the thick, forested mountains of Japan, forcing trains to stop. These “train centipedes,” supposedly for their famous obstructions, would appear every now and then – then disappear again for years at a time. Now scientists have figured out why.
It turns out that these centipede (Parafontaria laminata armigera), endemic to Japan, have an unusually long and synchronous eight-year life cycle. These long “periodic” life cycles – in which a population of animals move through the phases of life at the same time – have only been previously confirmed in some species of cicadas with life cycles of 13 and 17 years, as well as in bamboo and some other plants.
“This centipede is the first non-insect arthropod among all periodic organisms,” said lead author Jin Yoshimura, professor emeritus in the Department of Mathematics and Systems Engineering at Shizuoka University in Japan, who has been researching periodic cicadas in the past two. decades.
Related: Gallery: Dazzling photos of insects covered in dew
Train operators in Japan first observed an epidemic of train centipedes in 1920; they had to stop their train briefly while waiting for the creepy crawlers to pass on the tracks. According to various accounts, the centipedes returned about every eight years thereafter, each time forming a dense blanket impossible to pass through. In 1977, the first author Keiko Niijima, a researcher at the Forestry and Forest Products Research Institute, proposed for the first time that they could have a periodic cycle of eight years.
Now Niijima, Momoka Nii, also a professor in the Department of Mathematics and Systems Engineering at Shizuoka University, and Yoshimura have confirmed the life cycle using historical outbreak reports and detailed investigations. For many years, the authors have collected centipedes in the mountains of Honshu, Japan, and researched the creatures; they determined their life stages by counting the number of legs and body segments, as these are particular to the age of a centipede.
The researchers found that several broods of this population each have their own timing; in other words, one brood may be in the egg phase while another may be adult adults. Each population goes through its entire life cycle in eight years.
The brood of centipedes that periodically appears on the tracks has no affinity for the tracks or does not mean to be disruptive; on the contrary, the insects are simply trying to get to feeding areas that are sometimes on the other side of the tracks. It turns out that the railroad is an “obstacle” in their journey to new feeding grounds, Yoshimura told Live Science. To survive, these centipedes nibble on dead or decaying leaves sandwiched between the soil and fresh leaves on the surface, Yoshimura said.
Because they live in such large numbers, adults and seventh nymphs – the stage before they become adults – quickly munch on all the food available where they were born; and so they start a trek to move to a new feeding site, he said. At this second site, they eat the decaying leaves, mate, lay a batch of new eggs, and later die.
The researchers hypothesize that their extended life cycles may be synchronized with winter hibernation. Unlike periodic cicadas which emerge in large numbers and thus make each individual less likely to succumb to predators, these train centipedes do not need this extra protection from predators. They already have a fairly good defense mechanism: when attacked, they release poison cyanide, the researchers said.
The results were published on January 13 in the journal Royal Society Open Science.
Originally posted on Live Science.
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