WEBVTT - Jellyfish Are Brainless, But Still Sleepy

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<v Speaker 1>Welcome to brain stuff from how stuff works. Hey, brain stuff,

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<v Speaker 1>it's Christian saga. You probably don't think you have much

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<v Speaker 1>in common with a jellyfish, After all, their species don't

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<v Speaker 1>share elemental properties with you, like you know, a spine

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<v Speaker 1>or a brain, or even the same interests. The primitive

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<v Speaker 1>jellyfish in the genus Cassiopeia spends its time resting upside

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<v Speaker 1>down on the ocean floor rather than you know, waiting

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<v Speaker 1>for the next season of Game Thrones. Researchers, though, have

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<v Speaker 1>now discovered that you and old Cassiopeia are more alike

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<v Speaker 1>than anyone might have suspected. You both begin and end

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<v Speaker 1>your days with a little shut I yes, jellyfish sleep.

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<v Speaker 1>The study was published online in the September edition of

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<v Speaker 1>the journal Current Biology. Unlike most jellyfish, Cassiopeia jellyfish often

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<v Speaker 1>rest on the floor of mangrove swamps and seagrass beds

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<v Speaker 1>and rarely move from their under water spots. By lying

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<v Speaker 1>upside down, the jellyfish exposes the algae on its underside

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<v Speaker 1>to the sun, allowing it to photosynthesize and live off

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<v Speaker 1>the food the algae produces. Ravi Nath, the papers co

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<v Speaker 1>first author and a graduate student in cal texts Sternberg Laboratory,

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<v Speaker 1>says that it may not seem surprising that jellyfish sleep,

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<v Speaker 1>after all, mammals sleep, and other invertebrates such as worms

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<v Speaker 1>and fruit flies sleep, but Nath points out that jellyfish

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<v Speaker 1>are the most evolutionary ancient animals known to sleep. This

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<v Speaker 1>finding opens up many more questions, is sleep the property

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<v Speaker 1>of neurons, and perhaps a more far fetched question, do

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<v Speaker 1>plants sleep? To test whether the jellyfish were actually sleeping,

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<v Speaker 1>researchers set up cameras and found the jellyfish were largely

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<v Speaker 1>inactive at night, and they pulsed less during the day,

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<v Speaker 1>about thirty nine times compared to fifty eight times during

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<v Speaker 1>sunlight hours. Then the team discovered it was harder to

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<v Speaker 1>rouse the jellyfish at night too. They set up a

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<v Speaker 1>false bottom within the jellyfish tank and pulled the platform

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<v Speaker 1>out from under the jellyfish. When alert during the day,

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<v Speaker 1>the jellyfish immediately swam to the bottom of the tank.

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<v Speaker 1>At night, however, it took several seconds for the jellyfish

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<v Speaker 1>to awake before heading to the tank floor. The researchers

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<v Speaker 1>also demonstrated that sleep is essential to jellyfish, just like

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<v Speaker 1>it is to people. After keeping the jellyfish awake during

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<v Speaker 1>the night with pulses of water, the jellyfish were sluggish

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<v Speaker 1>and sleepy the next day, when they otherwise would have

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<v Speaker 1>been active. Mondays am I right. The discovery that jellyfish

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<v Speaker 1>sleep could be an important next step in sleep research

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<v Speaker 1>for all types of species. While the basis and function

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<v Speaker 1>of sleep is still a mystery to scientists, it's often

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<v Speaker 1>associated with the brain because sleep has a profound impact

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<v Speaker 1>on memory and learning. Jellyfish don't need a brain to sleep,

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<v Speaker 1>which could be a revolutionary concept for sleep science. Today's

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<v Speaker 1>episode was written by Laurie L. Dove, produced by Tristan McNeil,

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<v Speaker 1>and For more on this and other topics, please visit

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<v Speaker 1>us at how stuff works dot com.