Young jumping spiders have transparent bodies, so the retinas moving inside their eyes can be filmed at night. It is a rare chance to see what happens during rest. What showed up?
Bouts, at . The retinas moved fast, the legs twitched and sometimes curled in toward the body. That regularity is what separates noise from a defined state, and the combination recalls , the stage in which a mammal’s eyes move quickly. It is a hint at a similar sleep state in arthropods, and there is no way to know whether any experience of a dream came with it.
A young jumping spider has , so the retinas moving inside its eyes can be filmed at night. It is a window of opportunity: the transparency disappears with maturity.
Its front eyes are fixed, and it moves the retina inside to scan, so there is a functional parallel here to eye movement.
The researchers saw bouts recurring at regular intervals in which the retinas moved fast, the legs twitched and sometimes curled in toward the body. The regularity is what separates noise from a defined state.
The combination recalls the stage of sleep in which a mammal’s eyes move quickly, which makes this a hint at a similar state in arthropods. It is observational work in one species, movement like that is no proof of dreams, and it was not measured alongside electrical activity in the brain.
wat. In 34 young spiders, fast retinal movements, twitches and curling legs turned up together in nightly cycles.
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A complex sleep state may be far older and more widespread than supposed, in tiny brains very unlike ours.
How do we know?
The researchers filmed 34 young spiders at night, hanging on silk threads, and tracked the movement of the retina, the legs and the abdomen across cycles.
What is still unknown
This is observational work in one species. REM-like movement is no proof of dreams, and it was not measured alongside electrical activity in the brain.
Learn something?
Where to next
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