Speaker 1: Welcome to brain stuff from how stuff works. Hey, brain stuff,
Speaker 1: it's Christian saga. You probably don't think you have much
Speaker 1: in common with a jellyfish, After all, their species don't
Speaker 1: share elemental properties with you, like you know, a spine
Speaker 1: or a brain, or even the same interests. The primitive
Speaker 1: jellyfish in the genus Cassiopeia spends its time resting upside
Speaker 1: down on the ocean floor rather than you know, waiting
Speaker 1: for the next season of Game Thrones. Researchers, though, have
Speaker 1: now discovered that you and old Cassiopeia are more alike
Speaker 1: than anyone might have suspected. You both begin and end
Speaker 1: your days with a little shut I yes, jellyfish sleep.
Speaker 1: The study was published online in the September edition of
Speaker 1: the journal Current Biology. Unlike most jellyfish, Cassiopeia jellyfish often
Speaker 1: rest on the floor of mangrove swamps and seagrass beds
Speaker 1: and rarely move from their under water spots. By lying
Speaker 1: upside down, the jellyfish exposes the algae on its underside
Speaker 1: to the sun, allowing it to photosynthesize and live off
Speaker 1: the food the algae produces. Ravi Nath, the papers co
Speaker 1: first author and a graduate student in cal texts Sternberg Laboratory,
Speaker 1: says that it may not seem surprising that jellyfish sleep,
Speaker 1: after all, mammals sleep, and other invertebrates such as worms
Speaker 1: and fruit flies sleep, but Nath points out that jellyfish
Speaker 1: are the most evolutionary ancient animals known to sleep. This
Speaker 1: finding opens up many more questions, is sleep the property
Speaker 1: of neurons, and perhaps a more far fetched question, do
Speaker 1: plants sleep? To test whether the jellyfish were actually sleeping,
Speaker 1: researchers set up cameras and found the jellyfish were largely
Speaker 1: inactive at night, and they pulsed less during the day,
Speaker 1: about thirty nine times compared to fifty eight times during
Speaker 1: sunlight hours. Then the team discovered it was harder to
Speaker 1: rouse the jellyfish at night too. They set up a
Speaker 1: false bottom within the jellyfish tank and pulled the platform
Speaker 1: out from under the jellyfish. When alert during the day,
Speaker 1: the jellyfish immediately swam to the bottom of the tank.
Speaker 1: At night, however, it took several seconds for the jellyfish
Speaker 1: to awake before heading to the tank floor. The researchers
Speaker 1: also demonstrated that sleep is essential to jellyfish, just like
Speaker 1: it is to people. After keeping the jellyfish awake during
Speaker 1: the night with pulses of water, the jellyfish were sluggish
Speaker 1: and sleepy the next day, when they otherwise would have
Speaker 1: been active. Mondays am I right. The discovery that jellyfish
Speaker 1: sleep could be an important next step in sleep research
Speaker 1: for all types of species. While the basis and function
Speaker 1: of sleep is still a mystery to scientists, it's often
Speaker 1: associated with the brain because sleep has a profound impact
Speaker 1: on memory and learning. Jellyfish don't need a brain to sleep,
Speaker 1: which could be a revolutionary concept for sleep science. Today's
Speaker 1: episode was written by Laurie L. Dove, produced by Tristan McNeil,
Speaker 1: and For more on this and other topics, please visit
Speaker 1: us at how stuff works dot com.