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Sleeping Jellyfish

September 27, 2017

Snoozing jellyfish help scientists understand the origins of sleep.


Multiple Cassiopea jellyfish on the bottom of a tank. LGoentoro

BOB HIRSHON (host): Multiple Cassiopea jellyfish on the bottom of a tank. (L. Goentoro)

Snoozing jellyfish. I’m Bob Hirshon and this is Science Update.

A typical day for the Cassiopea jellyfish consists of sitting upside down on the seafloor, trailing its tentacles in the currents.

RAGI NATH (California Institute of Technology):

It sits in place, and it pulses, and that’s pretty much its behavioral repertoire.


That’s Caltech biologist Ravi Nath. He and his colleagues report in the journal Current Biology that despite its low-key lifestyle and lack of a brain, Cassiopea sleeps each night, pulsing more gently, ignoring stimuli and, if deprived of sleep, acts groggy and impaired. The discovery raises questions about the nature of sleep.


Is sleep a property of neurons? Or is sleep a property of complex circuits? How complex of a system do you need before you start seeing something sleep?


He says discovering sleep’s evolutionary origins will help scientists better understand the phenomenon in us. I’m Bob Hirshon, for AAAS, the science society.

Story by Bob Hirshon