Jellyfish have no brain, but they need their sleep, scientists discover

It was well past midnight when Michael Abrams, Claire Bedbrook and Ravi Nath crept into the Caltech lab in Pasadena where they were keeping their jellyfish.

They didn’t bother switching on the lights, opting instead to navigate the maze of desks and equipment by the pale blue glow of their cellphones. The students hadn’t told anyone that they were doing this. It wasn’t forbidden, exactly, but they wanted a chance to conduct their research without their PhD advisers breathing down their necks.

“When you start working on something totally crazy, it’s good to get data before you tell anybody,” Abrams said.

The “totally crazy” undertaking in question: an experiment to determine whether jellyfish sleep.

It had all started when Bedbrook, a graduate student in neurobiology, overheard Nath and Abrams mulling the question over coffee. The topic was weird enough to make her stop at their table and argue.

“Of course not,” she said. Scientists still don’t fully know why animals need to snooze, but research has found that sleep is a complex behaviour associated with memory consolidation and REM cycles in the brain. Jellyfish are so primitive they don’t even have a brain – how could they possibly share this mysterious trait?