The sloppecks have detected Signs of the phase of quick sleep, previously thought to be unique to mammals, birds, reptiles, and cephalopods. Behavioral ecologist Daniela Resossler accidentally noticed this phenomenon during the pandemic while observing her pet spiders.
Huntsmen spiders are known for their exceptional hunting abilities and advanced vision system. With eight eyes, including two large forward-facing ones similar to cats, they can accurately track their prey. They closely monitor movement and establish direct visual contact, a behavior uncommon in other species.
Resossler’s spiders displayed characteristics of a quick sleep phase, hanging from silk threads like Christmas tree ornaments, with regular limb twitching every 20-30 minutes. The movement of their eyes’ retinas during twitching resembled the rapid eye movement (REM) phase of sleep seen in mammals, marked by muscle atony and increased brain activity.
To confirm REM-like behavior in spiders, researchers conducted experiments using sound stimuli mimicking the frequency of flying insect wings, their natural prey. Interestingly, the insects needed stronger stimuli to wake them up while motionless at night.
Focusing on Portia spiders known for their cognitive abilities and adaptive hunting strategies, researchers aim to explore the impact of sleep deprivation on their hunting effectiveness compared to well-rested individuals.
While it’s challenging to prove spiders dream without verbal descriptions as humans provide, scientists speculate that any potential dreams in spiders may involve hunting or evading predators.
Following the initial findings, about 15 spiders were studied, all displaying signs of REM-like behavior. This discovery suggests that quick sleep might be more prevalent than previously believed.
Sleep plays a vital role in learning and memory formation across various animal species, including jellyfish with rudimentary brains showing sleep signs. Resossler highlights the importance of nocturnal spider observations, revealing complex processes existing in nature long before humans.