Individual recognition in a jumping spider (Phidippus regius)

Individual recognition is conceptually complex and computationally intense, leading to the general assumption that this social knowledge is solely present in vertebrates with larger brains, while miniature-brained animals in differentiating societies eschew the evolutionary pressure for individual recognition by evolving computationally less demanding class-level recognition, such as kin, social rank, or mate recognition. Arguably, this social knowledge is restricted to species with a degree of sociality (sensu Wilson, 2000, for a review Gherardi et al., 2012). Here, we show the exception to this rule in a non-social arthropod species, the jumping spider Phidippus regius. Using a habituation-dishabituation paradigm, we visually confronted pairs of spatially separated spiders with each other and measured the 'interest' of one spider towards the other. The spiders exhibited high interest upon initial encounter of an individual, reflected in mutual approach behaviour, but adapted towards that individual when it reoccurred in the subsequent trial, indicated by their preference of staying farther apart. In contrast, spiders exhibited a rebound from habituation, reflected in mutual approach behaviour, when a different individual occurred in the subsequent trial, indicating the ability to tell apart spiders' identities. These results suggest that P. regius is capable of individual recognition based on long-term memory.