Every 8 years something happens on the railway lines in Japan. A school of millipedes suddenly appears from the mountains in western Tokyo (Japan). They disrupt rail traffic and were therefore called “millipedes”. The reason for this behavior was unknown. But the mystery of the millipedes, which appear every 8 years, has already been solved. The investigation lasted 50 years.
Millipedes are about 3 cm. And they swarm over the railroad tracks with surprising regularity. In the end it was confirmed that the species (Parafontaria laminata armígera) has a life cycle of eight years. This discovery is surprising. So far, cicadas were the only known creatures with such a long duration of complete life development. This was confirmed by following their entire life story from eggs to adults in two different locations.
“This millipede takes seven years from egg to adult and another year to mature,” the scientists write. The study was published in The Royal Society Open Science.
Lead author Keiko Niijima began observing these species in 1972. As a result, between then and 2016, two main locations were examined two to five times a year over a long period of time.
«The soil was dug to a depth of 0 to 5 cm. A polyethylene film was spread out and the millipedes on the film were collected with tweezers or a vacuum cleaner, ”explain the scientists. “Then the same process was repeated for different depths,” they add. After collecting, the team found that millipedes have seven stages of growth (they are also called) Growth stages). They stay in the ground and hibernate in winter, but shed their fur in summer. “They grow up on the eighth move after eight years after laying eggs,” they emphasize.
In September and October, adults swarm on the surface, completely covering it. In winter they sometimes go up to 50 meters into hibernation and copulate again in late spring. For the month of August, the females laid 400 to 1000 eggs. Then all adults die and give way to another eight-year-old generation.
«The mystery of the millipedes, which come out every 8 years, has been solved. We have demonstrated the existence of a periodic millipede. It is a new addition for organisms with long periodic life cycles: cicadas, bamboo and some plants of the genus Strobilanthes, ”writes the team.
Parafontaria laminata armígera According to scientists, it is the first record of periodic arthropods other than insects. Arthropods and insects make up a large percentage of all animals on earth. But only a fifth of these species have been identified.