Some Spiders Hunt in Packs to Catch Prey

It's a synchronized ballet of stop and go as they converge on dinner.

social spider in a web

Bernard DuPont [CC BY-SA 2.0] / Wikimedia Commons

Most spiders are not very friendly. In fact, they can be territorial and aggressive toward each other.

But there are a few species that are social. They live in huge colonies, building large communal webs, and they raise their offspring and hunt together.

The Anelosimus eximius spiders of French Guyana, for example, are less than one-quarter of an inch long. They live in colonies of several thousand spiders in nests that can be more than 20 feet wide. The spiders work together to build and repair their webs.

But they also work together to catch, subdue, and eat prey. When something falls into their web, they coordinate their movements, working as a pack to capture prey that can be several hundred times the size of one individual spider.

Researchers recently studied this synchronized behavior and published their findings in the journal Proceedings of the National Academy of Sciences.

“I am generally interested in studying social behavior in diverse species of arthropods (spiders, ants, bees, cockroaches, drosophila). The overall aim of my research is to understand how various forms of cooperation and coordination (e.g. aggregation, division of labour) can emerge in social groups from relatively simple behavioral rules,” study author Raphaël Jeanson of the Research Center on Animal Cognition, University of Toulouse, France, tells Treehugger.

“In social spiders, the existence of synchronization during collective hunting was documented 30 years ago, but no study has so far explored the mechanisms underlying this collective phenomenon. I was always impressed by the speed with which the spiders synchronized and the 'quality' of their synchronization.”

Of the 50,000 known species of spiders, only about two dozen work together like this. When they hunt, they move and stop perfectly in unison as they go toward their prey. Then they share in the spoils.

“Many species of social spiders can cooperate to catch prey that would otherwise be inaccessible to single individuals, but cooperation can take different forms,” Jeanson says.

In most spider species, juvenile spiders are friendly for a few days before heading off to live solitary lives. But that’s not the case in these rare social spiders.

“A first form of cooperation is the fact that colony members build a common nest. Females also cooperate in rearing the brood. When hunting, social spiders can also attack the prey simultaneously and feed communally,” Jeanson says.

But in this study, researchers were interested in the pack-like simultaneous movements the spiders made when hunting their prey.

Understanding Synchronization

Anelosimus eximius spiders sharing a meal
Anelosimus eximius spiders sharing a meal.

Raphael Jeanson / CNRS/University of Toulouse

For their work, researchers used both fieldwork and modeling to investigate what caused these synchronized movements. Because they wanted to be able to trigger the collective hunting behavior in the Anelosimus eximius, an engineer working on the project designed a vibratory device that allowed them to stimulate the spiders in a repeatable way.

“This was important because we needed to control the timing of the stimulation to demonstrate that it was not the frequency of the prey vibrations that acted as a pacemaker giving the oscillation rhythms,” Jeanson says.

They were analyzing a spider’s decision to move, based on the intensity of vibrations emitted by the prey and by the other moving spiders.

“When the lure was removed from the web for a few seconds, we observed that the spiders continued to move synchronously and that the oscillations were even more pronounced than when the bait was present,” Jeanson says. “This experimental procedure allowed us to demonstrate that synchronization came from interactions between spiders via the perception of vibrations.”

The researchers concluded that there was no leader to coordinate the movement and activities of the rest of the spiders. Instead, each spider responds to the amount of vibration from the prey relative to the vibration from other spiders in order to decide when to stop and when to move.

“Synchronization occurs through self-organizing principles that allow hunting spiders to adapt quickly to any type of prey (small or large) or the number of spiders involved in the hunt,” Jeanson says.

Synchronization is found in all living systems from cells to ecosystems, the researchers point out. These findings help identify a new method of synchronization.

“Our study also contributes to our understanding of the principles that govern coordination in animal groups,” Jeanson says. “This is particularly important in spiders, which are still poorly studied compared to other more iconic and charismatic social species such as ants or bees.”

View Article Sources
  1. Elwood, Robert W., and John Prenter. “Aggression in Spiders.” Cambridge University Press, 2013, pp. 113–133.

  2. Chiara, Violette, et al. "A Variable Refractory Period Increases Collective Performance in Noisy Environments." Proceedings of the National Academy of Sciences, vol. 119, no. 12, 2022, doi:10.1073/pnas.2115103119

  3. Carrell, Skyler. "Anelosimus eximius." Animal Diversity Web.

  4. study author Raphaël Jeanson of the Research Center on Animal Cognition, University of Toulouse, France

  5. study author Raphaël Jeanson of the Research Center on Animal Cognition, University of Toulouse, France,