1 00:00:02,040 --> 00:00:07,360 Speaker 1: Welcome to brain stuff from how stuff works. Hey, brain stuff, 2 00:00:07,360 --> 00:00:10,039 Speaker 1: it's Christian saga. You probably don't think you have much 3 00:00:10,080 --> 00:00:13,239 Speaker 1: in common with a jellyfish, After all, their species don't 4 00:00:13,280 --> 00:00:16,599 Speaker 1: share elemental properties with you, like you know, a spine 5 00:00:16,680 --> 00:00:19,599 Speaker 1: or a brain, or even the same interests. The primitive 6 00:00:19,720 --> 00:00:24,360 Speaker 1: jellyfish in the genus Cassiopeia spends its time resting upside 7 00:00:24,400 --> 00:00:27,360 Speaker 1: down on the ocean floor rather than you know, waiting 8 00:00:27,360 --> 00:00:30,479 Speaker 1: for the next season of Game Thrones. Researchers, though, have 9 00:00:30,680 --> 00:00:34,760 Speaker 1: now discovered that you and old Cassiopeia are more alike 10 00:00:34,800 --> 00:00:38,559 Speaker 1: than anyone might have suspected. You both begin and end 11 00:00:38,600 --> 00:00:42,640 Speaker 1: your days with a little shut I yes, jellyfish sleep. 12 00:00:43,080 --> 00:00:47,400 Speaker 1: The study was published online in the September edition of 13 00:00:47,440 --> 00:00:53,440 Speaker 1: the journal Current Biology. Unlike most jellyfish, Cassiopeia jellyfish often 14 00:00:53,520 --> 00:00:58,080 Speaker 1: rest on the floor of mangrove swamps and seagrass beds 15 00:00:58,120 --> 00:01:01,640 Speaker 1: and rarely move from their under water spots. By lying 16 00:01:01,760 --> 00:01:06,120 Speaker 1: upside down, the jellyfish exposes the algae on its underside 17 00:01:06,120 --> 00:01:10,240 Speaker 1: to the sun, allowing it to photosynthesize and live off 18 00:01:10,240 --> 00:01:14,520 Speaker 1: the food the algae produces. Ravi Nath, the papers co 19 00:01:14,760 --> 00:01:20,120 Speaker 1: first author and a graduate student in cal texts Sternberg Laboratory, 20 00:01:20,200 --> 00:01:23,560 Speaker 1: says that it may not seem surprising that jellyfish sleep, 21 00:01:23,920 --> 00:01:28,000 Speaker 1: after all, mammals sleep, and other invertebrates such as worms 22 00:01:28,040 --> 00:01:31,559 Speaker 1: and fruit flies sleep, but Nath points out that jellyfish 23 00:01:31,600 --> 00:01:36,080 Speaker 1: are the most evolutionary ancient animals known to sleep. This 24 00:01:36,200 --> 00:01:40,200 Speaker 1: finding opens up many more questions, is sleep the property 25 00:01:40,240 --> 00:01:44,160 Speaker 1: of neurons, and perhaps a more far fetched question, do 26 00:01:44,440 --> 00:01:48,680 Speaker 1: plants sleep? To test whether the jellyfish were actually sleeping, 27 00:01:48,960 --> 00:01:52,320 Speaker 1: researchers set up cameras and found the jellyfish were largely 28 00:01:52,440 --> 00:01:55,960 Speaker 1: inactive at night, and they pulsed less during the day, 29 00:01:56,000 --> 00:01:59,520 Speaker 1: about thirty nine times compared to fifty eight times during 30 00:01:59,560 --> 00:02:03,080 Speaker 1: sunlight hours. Then the team discovered it was harder to 31 00:02:03,280 --> 00:02:06,640 Speaker 1: rouse the jellyfish at night too. They set up a 32 00:02:06,680 --> 00:02:10,720 Speaker 1: false bottom within the jellyfish tank and pulled the platform 33 00:02:10,840 --> 00:02:14,080 Speaker 1: out from under the jellyfish. When alert during the day, 34 00:02:14,320 --> 00:02:17,480 Speaker 1: the jellyfish immediately swam to the bottom of the tank. 35 00:02:17,800 --> 00:02:21,440 Speaker 1: At night, however, it took several seconds for the jellyfish 36 00:02:21,440 --> 00:02:25,560 Speaker 1: to awake before heading to the tank floor. The researchers 37 00:02:25,600 --> 00:02:29,280 Speaker 1: also demonstrated that sleep is essential to jellyfish, just like 38 00:02:29,320 --> 00:02:33,000 Speaker 1: it is to people. After keeping the jellyfish awake during 39 00:02:33,000 --> 00:02:36,440 Speaker 1: the night with pulses of water, the jellyfish were sluggish 40 00:02:36,520 --> 00:02:39,640 Speaker 1: and sleepy the next day, when they otherwise would have 41 00:02:39,720 --> 00:02:44,440 Speaker 1: been active. Mondays am I right. The discovery that jellyfish 42 00:02:44,480 --> 00:02:48,360 Speaker 1: sleep could be an important next step in sleep research 43 00:02:48,440 --> 00:02:52,239 Speaker 1: for all types of species. While the basis and function 44 00:02:52,320 --> 00:02:55,720 Speaker 1: of sleep is still a mystery to scientists, it's often 45 00:02:55,720 --> 00:02:59,880 Speaker 1: associated with the brain because sleep has a profound impact 46 00:03:00,280 --> 00:03:04,959 Speaker 1: on memory and learning. Jellyfish don't need a brain to sleep, 47 00:03:05,080 --> 00:03:15,359 Speaker 1: which could be a revolutionary concept for sleep science. Today's 48 00:03:15,400 --> 00:03:19,240 Speaker 1: episode was written by Laurie L. Dove, produced by Tristan McNeil, 49 00:03:19,360 --> 00:03:22,360 Speaker 1: and For more on this and other topics, please visit 50 00:03:22,440 --> 00:03:34,600 Speaker 1: us at how stuff works dot com.