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Do spiders dream? Recent research indicates that, like humans, jumping spiders are able to dream. Konstanz biologist Dr Daniela Rößler and her team of researchers document jumping spiders (Evarcha arcuata) experiencing a state similar to active REM sleep in humans. This research on terrestrial invertebrates expands our understanding of the evolution of sleep in animals and begs the question: Do jumping spiders experience visual dreams? The findings were published in the scientific journal PNAS on XX.

REM sleep (Rapid Eye Movement) has been studied thoroughly in mammals and birds, and it has been documented in reptiles and cephalopods. Many animals, including the vast majority of arthropods, do not have movable eyes, which makes comprehensive comparisons of active sleep-like states across lineages difficult. Although jumping spiders are unable to move the lenses of their eyes, they can however move their "retinal tubes" to adjust their gaze.

Phases of clear retinal movements

The authors of the study recorded and analyzed nocturnal infrared footage of 34 young jumping spiders. Since the skin of the newly emerged spiders is not yet pigmented, the authors were able to directly observe the spiders' retinas. The spiders exhibited phases of clear retinal movements that took place at very regular intervals. These phases increased in length over the course of the night.

The retinal movements were always accompanied by uncontrolled movements of the body, like curling of the legs or twitching of single limbs or the spinnerets. Here there are surprising similarities to REM sleep seen in other animals. The authors observed similar leg movements at regular intervals in adult jumping spiders as well.

About Daniela Rößler

Daniela Rößler is a behavioural and evolutionary ecologist. Since May of 2021, she has been a postdoctoral fellow in the Zukunftskolleg and the Department of Biology at the University of Konstanz as well as at the Max Planck Institute of Animal Behavior. Her research interests include animal colouration, sensory ecology and animal behaviour with a focus on anti-predator adaptations.

Natural history observations from the field form the basis for most of her research questions. She uses integrative and interdisciplinary approaches in both the field and the lab to experimentally test the function of signals and/or behaviour. Daniela Rößler focuses on visual signals, cognition and anti-predator adaptations in jumping spiders. She is currently studying the ecology of fear and sleep in jumping spiders.

The Zukunftskolleg

The Zukunftskolleg is a University of Konstanz research facility dedicated to the promotion of early career researchers who have completed their doctorate but have not yet been appointed to a professorship. It provides an interdisciplinary working environment with excellent research conditions and the greatest possible freedom. The Zukunftskolleg is funded in the context of the German Excellence Strategy and by the Hector-Stiftung II.

Key facts:

• Original publication: Rößler, D.C., Kim, K., De Agrò, M., Jordan, A., Galizia, C.G., Shamble, P.S.: Regularly occurring bouts of retinal movements suggest an REM sleep-like state in jumping spiders. PNAS Vol. 119, Nr. 33. DOI: https://doi.org/10.1073/pnas.2204754119
• Dr Daniela Rößler from the Zukunftskolleg/Department of Biology at the University of Konstanz and the Max Planck Institute of Animal Behavior discovers jumping spiders experience a state similar to REM sleep.
• More information about Daniela Rößler: http://danielaroessler.weebly.com/
• More information about the Zukunftskolleg: https://www.uni-konstanz.de/zukunftskolleg/