Brainless Jellyfish that Sleeps

The Cassiopea jellyfish spends most of its life resting upside down while underwater
The Cassiopea jellyfish spends most of its life resting upside down while underwater

Historical Context

A group of students at the California Institute of Technology decided to find out one thing: if jellyfish sleep. This may seem innocuous, but jellyfish do not have brains, and scientists think sleep is rooted in a need to consolidate memory, among other things, in the brain.

So after months of late-night research, the students figured out that yes, the Cassiopea jellyfish exhibits sleep like behavior, suggesting that sleep is rooted more deeply in our biology than we realize. This makes the cassiopea the first known brainless animal to sleep - the jellyfish does not have a brain to speak of, just a diffuse set of nerve cells.

The study appears to show that sleep is a function developed very early on in the existence of life, and it has persisted, for reasons not clearly understood by scientists. Perhaps the brainless jellyfish is the answer...

Photo Info


Photographer: Chris Hind
Location taken: Florida Keys, Florida, USA

Source: Wikimedia Commons

Related Events

  • 2017-09-21 Discovery of the first brainless animal that sleeps, the jellyfish Cassiopea, research published in "Current Biology" by Caltech scientists

Related Articles and Photos

Historical Photos