STATES CHRONICLE – Scientists have determined that the Cassiopea jellyfish rests at night, which came as quite a surprise. It is the first concrete evidence that animals without a brain can enter a sleep-like state.
A team from the California Institute of Technology in Pasadena found that jellyfish responded up to 33 percent slower to stimuli during the night than during the day. They also found that when jellyfish were forced to stay awake at night, they responded up to 17 percent slower the next day. Previously, scientists believed that only animals with a brain were capable or needed to sleep.
More Questions Raised About Sleep because of the Cassiopea jellyfish
The team used the jellyfish’s position to determine if it was awake or asleep. This species sits on the ocean floor with their tentacles pointed up into the air when in a sleep-like state and also during the day. They also move their tentacles at a much slower rate. The student scientists say that this is the first time that the effect was investigated in an animal that did not have a brain or a central nervous system.
Now, the team is hoping to figure out why an animal leaves itself open to predators for a good share of the day because it is asleep. The researchers also want to understand why animals have never devised a way to go without resting in a sleep-like state, or if it was possible.
Thomas Bosch, an evolutionary biologist at Kiel University in Germany, says that: “The simplicity of these organisms is a door opener to understand why sleep evolved and what it does.”
Scientists will reportedly be looking to determine a gene that makes animals, and also humans, need to close their eyes and rest. Researchers point out that the role of resting soundly is very poorly understood.
This study of the Cassiopea jellyfish serves to raise new questions about the evolution of this behavior. Understanding when and why sleep began and isolating the gene that might be causing people to enter a sleep-like state may hold important clues in helping people get a better rest, possibly even more.
Study results are available in the journal Current Biology.
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