A JELLICIOUS STORY

 SLEEPING JELLY BEAUTY

                                                          DATE :- 08.07.21

Jellyfish doesn't have the so called brain but still they are able to show the sleeplike state on a particular time of the day which is revealed in a new research findings. 

They don't have brains, or even anything more than a rudimentary nervous system, but jellyfish apparently do have bedtimes.

New research finds that jellyfish enter a sleep-like state. If the study, published in the journal Current Biology, is confirmed by future studies, jellyfish are the first-ever animals with no central nervous system to have been observed sleeping. That finding could bolster the theory that sleep is an emergent property of neurons — in other words, sleep might be something that nerve cells connected in a network just do, even without complex organization. 

ORIGIN OF SLEEP IN THE CONTEXT OF JELLY FISH

One research scholar from CALTECH ; Michael Abrams, happened to be cultivating jellyfish in the lab of biologist Lea Goentoro at the same time for an entirely unrelated project. He noticed that one genus, Cassiopea, or the upside-down jellyfish, seemed to become less active at night. Cassiopea spends the vast majority of its time sitting upside down on the ocean or tank floor, pulsing its bell about once a second, Abrams told Live Science. This sedentary behavior makes the upside-down jellyfish an easy animal to track behaviorally.

SNOOZING JELLIES

Abrams and Nath joined forces with Benbrook to investigate just what the jellies were doing. They knew that to show that the jellyfish were sleeping, they'd have to prove that their behavior met the standard criteria for sleep: decreased activity that is rapidly reversible, unlike a coma or unconsciousness; reduced responsiveness to stimuli compared to a waking state; and homeostatic regulation, meaning there is some sort of innate "drive" toward sleep and that the animal needs sleep to function.

AN EXPERIMENT 

To measure activity, the researchers counted the rate of the bell's pulsation in 23 jellyfish for six straight days and nights. They found that the rate dropped by 32 percent at night, going from about 1,155 pulses per 20 minutes during the day to 781 pulses per 20 minutes at night. When the researchers put a little midnight snack in the water column, the jellies perked up and started pulsing at daytime rates, indicating that this quiescent period was easily reversible.

Cassiopea jellyfish, known as upside-down jellyfish for their preferred position, appear to sleep at night. (Image credit: Caltech)