Brainless Jellyfish Show Three Signs of Sleep
Like humans, mice, fish and flies, the upside-down jellyfish Cassiopea exhibits the telltale signs of sleep, scientists report September 21, 2017 in the journal Current Biology. But unlike other animals that slumber, jellyfish don’t have a central nervous system.
“It’s the first example of sleep in animals without a brain,” says study coauthor Paul Sternberg, a Howard Hughes Medical Institute investigator at the California Institute of Technology. The findings push the origin of sleep further down the evolutionary tree of life – to before the emergence of a centralized nervous system.’
Scientists have long debated why animals sleep. Theories involve everything from memory, to learning, to cellular recovery. But Sternberg wants to answer something seemingly much more basic. The big question, he says, is “Do all animals sleep?”
It’s a controversial subject. All vertebrates that scientists have studied sleep, but whether the same is true for invertebrates remains a mystery. Researchers have demonstrated that fruit flies sleep, and Sternberg and others have argued that a roundworm called Caenorhabditis elegans does too. But not everyone’s convinced. And sleep in more primitive animals – like sponges and jellyfish – is even more nebulous. “We wanted to figure this out once and for all,” Sternberg says.
Cassiopea jellyfish can swim, but prefer to remain stationary on the sea (or tank) floor, with their bells on the ground, and their tentacles floating above them.
“We went in at night and videotaped them with an iPhone,” he says. After recording the jellies for a minute at night and a minute during the day, the team manually counted individual pulses and got their first clue that Cassiopea might be sleeping: they pulsed less frequently at night. The researchers then created an image processing program to count the pulses of 23 jellies over six consecutive days and nights. Pulsing activity ebbed at night, as the researchers had observed earlier, but a little food dropped in the tanks could quickly wake the jellies up again.
“It’s like the odor of coffee permeating your consciousness in the morning,” Sternberg says. Such an easy wake up is a sign that Cassiopea’s sluggish night-time behavior is due to sleep, not paralysis or coma.
Researchers spotted a second sign of sleep after dropping the floor out from dozing jellies. The team placed Cassiopea inside a PVC pipe with a mesh bottom and then dipped the pipe into the tank – so submerged jellies rested on the mesh instead of the tank floor. Then the researchers lowered the pipe deeper into the tank, forcing the jellies to lift off the mesh and float in open water. They don’t like that, Sternberg explains. During the day, Cassiopea will quickly pulse their bells and swim down to rest on the mesh again. But at night, it takes them about three times longer to start pulsing. It’s like the jellyfish are a little groggy, he says. This delayed response to stimulation is typical for sleeping animals.
Of all the animals that scientists know can sleep, Cassiopea jellyfish (shown) are the only ones that don’t have a centralized nervous system.
Credit: Caltech
And like other animals that sleep, jellyfish that pull an all-nighter pay for it the next morning. Nath and colleagues squirted tiny jets of water at Cassiopea for six or 12 hours at night, and then counted the jellies’ pulses the next day. They’re less active after losing sleep, Nath says, but “after they catch up on their sleep, they return to normal.”
The results suggest that Cassiopea do indeed sleep, but for Sternberg, the work is also sparking more questions. “Do you need neurons to sleep?” he asks. “Do you need more than one cell to sleep?” He’d like to study sponges, or even protozoa, next and perhaps push the origin of sleep back even further.
Source: http://www.ineffableisland.com/2017/09/brainless-jellyfish-show-three-signs-of.html
Anyone can join.
Anyone can contribute.
Anyone can become informed about their world.
"United We Stand" Click Here To Create Your Personal Citizen Journalist Account Today, Be Sure To Invite Your Friends.
Please Help Support BeforeitsNews by trying our Natural Health Products below!
Order by Phone at 888-809-8385 or online at https://mitocopper.com M - F 9am to 5pm EST
Order by Phone at 866-388-7003 or online at https://www.herbanomic.com M - F 9am to 5pm EST
Order by Phone at 866-388-7003 or online at https://www.herbanomics.com M - F 9am to 5pm EST
Humic & Fulvic Trace Minerals Complex - Nature's most important supplement! Vivid Dreams again!
HNEX HydroNano EXtracellular Water - Improve immune system health and reduce inflammation.
Ultimate Clinical Potency Curcumin - Natural pain relief, reduce inflammation and so much more.
MitoCopper - Bioavailable Copper destroys pathogens and gives you more energy. (See Blood Video)
Oxy Powder - Natural Colon Cleanser! Cleans out toxic buildup with oxygen!
Nascent Iodine - Promotes detoxification, mental focus and thyroid health.
Smart Meter Cover - Reduces Smart Meter radiation by 96%! (See Video).