Jellyfish Cassiopea, first animal without a brain or central nervous system but still it sleeps

Jellyfish Cassiopea, first animal without a brain or central nervous system but still it sleeps. Photo: Pixabay

New Delhi, September 25: We tend to think that during sleep we restore our brains and a time to process memories to prepare for a new day. But even animals that do not have brains need to sleep. According to reliable sources, Scientists have found that jellyfish go into a sleep-like state, making them the first animal without a brain or central nervous system to do like that.

Howard Hughes from California Institute of Technology in the US. Researchers  studied Cassiopea that is a  stationary jellyfish native to mudflats, mangrove swamps, and other warm, shallow waters. These were kept in tanks with artificial seawater in labs. Cassiopea do not look like a typical jellyfish but they are silver dollar-sized, splotched with black pigment, and rest upside-down on the sea floor.

The tentacles of Cassiopea are curled above bell-shaped bodies and they resemble miniature heads of cauliflower. However, they pulse like other jellyfish, contracting and relaxing in a steady rhythm, and researchers wondered if the behavior was continuous. According to official sources, Ravi Nath who is a graduate student at Caltech said that “We went in at night and videotaped them with an iPhone. After recording the jellies, the team got their first clue that Cassiopea might be sleeping: They pulsed less frequently at night. Researchers then created an image processing programme to count the pulses of 23 jellies over six consecutive days and nights.”
As previously observed, the pulsing activity diminished at night but a little food dropped in the tanks could quickly wake the jellies up again. A second sign of sleep was observed by the researchers after dropping the floor out from dozing jellies. Cassiopea was placed inside a pipe with a mesh bottom and later on dipped the pipe into the tank so that the submerged jellies could rest on the mesh instead of the tank floor.Then they lowered the pipe deeper into the tank, forcing the jellies to lift off the mesh and float in open water. However, at night, it takes them about three times longer to start pulsing. It is like the jellyfish are a little groggy.