Jellyfish also take a nap

washington - Also a calf- one of the oldest species in the world- needs sleep. This is shown by a study by the California Institute of Technology, published in Current Biology. Scientists had previously found that invertebrates such as fruitflies and worms that did, now it is also clear that the primitive malignant type of Cassiopea is a pretext.

'The findings indicate that even these animals need to sleep without central nervous system. That means sleep is one of the oldest behaviors, deeply rooted in the lineage of species, 'said team leader Ravi Nath.

Jellyfish have flourished for 600 million years in the world's seas and developed as one of the first nerve cells. Cassiopea, also known as the upside-down calf because he is on his back with the tentacles up, occurs in large numbers in clear, shallow tropical waters. The animals are 2.5 to 5 centimeters tall and plankton live.

Nath's experiments have shown that the culprit meets three key sleep criteria: 'Periods of limited activity, reduced sensitivity to stimuli and louder rest after sleep'.