Two distinct sleep stages emerge in jumping spider, including a REM-like state

Humans and other vertebrates go through various stages of sleep, including REM (rapid eye movement) sleep characterized by rapid eye movements and muscle twitches. Can a similar sleep state be observed in spiders? Researchers from the Institute of Organismic Biology at the University of Bonn investigated this in the Australian jumping spider Portia fimbriata. The work is published in the journal Proceedings of the National Academy of Sciences.