The unusual behavior of jellyfish turned out to be a dream
Scientists have shown that animals without nervous systems exhibit signs of sleep. The study was published in the journal Current Biology.
Sleep is a reduction reaction of vertebrates, worms and insects in the world. It is due to the presence of the organisms circadian rhythms — daily fluctuations in biological processes. Until this study, scientists had no evidence that animals without a Central nervous system unable to sleep.
From the point of view of evolution, jellyfish are the oldest animals, and biologists have wondered whether the sleep state of the presence of neurons.
Scientists from the California Institute of technology came to the conclusion that sleep is an ancient process that has not changed in the course of evolution. So, the Cassiopea jellyfish is also able to sleep.
To be considered dormant, the body needs to demonstrate periods of limited activity or calm and respond poorly to stimuli. Also the body must “want to sleep”. So, during sleep people are inactive, ignore the sounds and light, and in the case of lack of sleep can sleep. The dream of jellyfish also meets the criteria.
To monitor marine animals, a team of scientists has established a system of cameras for round the clock observations of jellyfish. They found that jellyfish are inactive at night and pulsate around 39 times per minute, while during the day their surge is 58 times per minute. Then the researchers tried to prove that animals had an increased threshold of excitation during the period of reduced activity. Medusa laid on the platform, and as soon as she fell asleep, a platform from under it removed. Sleepless Medusa would immediately sink to the bottom of the tank, but the sleeping Medusa drifted to five seconds before you Wake up and take a familiar position.