Adorable jumping spiders that aren’t considered to be social critters may be able to remember one another. The curious finding comes from a pre-print into Phidippus regius, a big-eyed spider species that behaved differently towards jumping spiders it had "met" before, compared to those that were total strangers.
Individual recognition is considered to be a trait that's specific to big-brained social animals who have the cognitive capacity for the computationally intense process of remembering faces. After all, it’s more important to remember other individuals if you are going to be interacting with them socially, whereas if you live mostly independently, you really only need to be able to recognize the basics: like if someone is kin or a potential mate.
“Arguably, this social knowledge is restricted to species with a degree of sociality,” write the authors of a pre-print in bioRxiv that hasn’t yet undergone peer review. “Here we show the exception to this rule in an asocial arthropod species, the jumping spider (Phidippus regius).”
The methodology used a habituation–dishabituation paradigm by confronting spiders with other jumping spiders they hadn’t met before. They were then separated and reintroduced, to see if and how differently they reacted towards spiders they had met before versus those they hadn’t.
Where jumping spiders were introduced to spiders they’d never met, they exhibited interest in the form of mutual approach behavior, which basically involves them getting a little closer to each other to get a better look. However, when they were reintroduced, they appeared to show less interest in the spiders they had already seen, demonstrated by the fact that they kept at their preferred distance and didn’t approach the “familiar face”. If another new spider was thrown into the mix, they would go back to showing interest through mutual approach behavior.
“These results suggest that P. regius is capable of individual recognition based on long-term social memory,” write the authors.
It wouldn’t be the first time jumping spiders have exhibited a trait that was previously thought to be associated with sociality. In 2021, researchers discovered that jumping spiders possess biological motion perception, which is the ability to interpret something like a video of moving dots as representing a living thing, and not just dots.
They also display REM-like sleep behavior, suggesting that they might even dream – and if this pre-print makes it through to publication – perhaps they’re dreaming about their spider friends (or foes).
The pre-print is available at bioRxiv.