Buzz
Ants are often territorial and highly aggressive. While this might not be problematic if ants lived alone, they typically form massive colonies, sometimes comprising tens of thousands of individuals. For larger predators that feed on ants, creatures that mimic ants for protection, or organisms that parasitize them, these large numbers are advantageous. They provide ample opportunities for predation or seamless integration into the group.
The jumping spider Phintella piatensis doesn’t consume ants, imitate them, or act as a parasite. Yet, it frequently associates with ants. In a field study, 90% of observed Phintella spiders were found near ants, including the aggressive Asian weaver ant Oecophylla smaragdina. This behavior baffles researchers, as Oecophylla is a known predator of spiders. Surprisingly, Phintella thrives in their presence, with survival rates significantly higher than other jumping spiders and comparable to those that mimic or prey on ants.
Scientists are intrigued by why Phintella would associate with ants it should logically avoid, especially when no clear benefit is apparent. Additionally, they question why the ants don’t prey on these spiders despite their predatory nature.
The solution to the first question lies in “something more terrifying than an ant.” For jumping spiders in the Philippines, this threat comes from spitting spiders of the genus Scytodes. Unlike most spiders that use venomous bites and silk webs, these spiders combine silk and venom into a sticky projectile, which they “spit” to immobilize and poison their prey. Once trapped, the spider delivers an additional venomous bite to liquefy the prey’s tissues. Phintella often falls victim to this method, as Scytodes spiders construct their webs above Phintella nests, ambushing them as they move in and out.
Scytodes avoids weaver ants, prompting New Zealand biologists Ximena Nelson and Robert Jackson to hypothesize that Phintella associates with ants for safety. In lab experiments, they observed that jumping spiders were more inclined to build nests when ants were present, either visibly or through scent, compared to other insects or no ants. Conversely, spitting spiders avoided building webs near ants and faced higher mortality rates in their presence, while Phintella largely escaped predation.
Nelson and Jackson concluded that the contrasting behaviors and survival rates of the two spiders indicate Phintella stays near ants to deter or eliminate spitting spiders. Although ants might prey on Phintella, the jumping spider employs unique strategies to transform this risky environment into a protective refuge.
First, Phintella nests differ from typical spider webs, resembling silken cocoons that deter intruders. The spider enhances nest security with a tightly woven silk layer, making it difficult for ants to penetrate. Additionally, the nest features hinged flaps at both ends, functioning as doors. This allows Phintella to enter and exit freely while keeping ants at bay.
