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Do spiders understand revenge?

Spiders are fascinating creatures that inhabit nearly every ecosystem on the planet. With over 47,000 known species, spiders display an incredible diversity of behaviors, hunting strategies, and adaptations. One captivating question that often arises about spiders is whether they are capable of seeking vengeance or retaliation when threatened or harmed. Here we’ll explore what the scientific evidence reveals so far about spiders’ cognitive capacities in relation to feelings of revenge.

What does it mean to “understand revenge”?

When investigating animal cognition and emotion, it’s important first to define what we mean by complex terms like “understanding revenge.” True understanding of revenge would likely involve some capacity for complex emotions like anger or resentment, coupled with intentional planning and forethought to punish someone who has wronged you. It would go beyond simple reflexive aggression or defensive behaviors. At a basic level, a desire for revenge requires an ability to remember specific individuals who have harmed you, as well as cognitive skills to devise plans to return the favor.

Most researchers agree that spiders lack the neural complexity for emotions like anger, holding grudges, or feeling resentment. However, some argue that spiders could display more simple forms of vengeance, stemming from a drive to punish predators or threats. This would require basic learning and memory capacities that some spiders appear to possess.

Spider brains and cognition

To understand spider cognition, we first need to examine their brains and nervous systems. All spiders have central nervous systems, but they are relatively simple compared to vertebrate brains. Their nervous systems contain far fewer neurons. Most spider brains have several clustered nerve cell bodies, connected by nerve fibers extending throughout the body like a decentralized network.

The jumping spider has one of the most complex spider nervous systems studied so far. Research has uncovered surprising learning, problem-solving, and visual processing abilities in jumping spiders. Their principal eyes have high resolution and depth perception for hunting. Their brains appear capable of advanced eyesight and visual processing compared to other spiders. But even jumping spiders have only around 600,000 neurons in their principal eyes’ retina, compared to over 100 million neurons in the human retina.[1]

Overall, most neuroscience experts agree that no spiders have the neural complexity required for emotions like anger or holding grudges against specific individuals who have wronged them.[2] Their brains are simply too decentralized and lack the higher processing power of the human cortex required for such complex thoughts.

Examples of spider behaviors related to retaliation

While spiders may not feel true revenge, some of their documented behaviors suggest forms of retaliation that could appear like vengeance on the surface:

  • Biting predators: Some spiders will bite predators that threaten them, like hedgehogs or shrews. Their venomous bites can even kill small mammal predators, which could select for this behavior evolutionarily. However, their bites likely stem from innate instinct rather than any calculated payback.
  • Increased aggression after losing: One study showed that pairs of jumping spiders became more aggressive towards other jumping spiders after losing contests over prey.[3] They bit winners that subsequently approached them. This shows they can learn from negative experiences, but probably doesn’t reflect complex vengeful planning.
  • Blocking burrow entrances: Trapdoor spiders aggressively block burrow entrances once disturbed by predators. They use webs, soil and debris to barricade burrows, making it harder for predators to access them.[4] This demonstrates adaptive learning, but likely not emotions like spitefulness.

In all these cases, the spiders’ aggressive behaviors appear reactive and instinct-driven. They help deter predators and future threats. But they likely don’t reflect deep-seated desires for payback or retaliation.

Studies testing spider cognition and learning

A handful of controlled studies have tested spider cognition in the lab, shedding light on their capacities for learning, memory and decision making. For example:

  • Jumping spiders can be trained to leap specific distances and directions to receive food rewards, showing adaptable learning.[5]
  • Studies show jumping spiders can mentally retrace complex routes and spatial orientations, indicating impressive spatial recall and mapping.[6]
  • Research found a type of orb-weaver spider could track and retain memories of up to three different prey insects captured in its web, choosing to consume the most nutritious one. This demonstrates they can form memories of multiple stimuli.[7]

Overall though, spider cognition appears limited to basic associative learning, spatial memory, and stimulus discrimination. As far as we know, they lack the neural complexity for emotion processing, holding grudges or anything resembling human-like revenge.


Based on our current scientific understanding, there is no evidence that spiders have the capacity for deep emotions like anger, resentment or desires for payback against things that have threatened or harmed them. Their brains simply don’t have the sophistication required for this complex thought.

Some spiders do show intriguing learning capacities in lab experiments, as well as aggressive behaviors in nature that could deter predators. But these likely stem from simpler forms of conditioning and innate instinct, not advanced cognition. While some spider behaviors may superficially resemble acts of vengeance, they do not reflect a deeper understanding of revenge or emotional motivations like spitefulness.

In the future, more complex neuroscience research could provide deeper insights into spider brains. This could reveal more advanced cognitive capacities than currently documented. But for now, the consensus is that spider brains are simply too rudimentary for emotions involved in true understanding of revenge.


[1] Harland, D.P., and Jackson, R.R. (2000). Eight-legged cats and how they see: a review of recent research on jumping spiders. Cimbebasia, 16, pp.231-240.

[2] Eberhard, W.G. (2019). The Spiders of the New World: An Introduction to the Spiders of North and South America. E. Barrie McGuire, Raleigh, NC.

[3] Harland, D.P. and Jackson, R.R. (2004). Portia Perceptions: The Umwelt of an Araneophagic Jumping Spider. In Complex Worlds from Simpler Nervous Systems (pp. 5-40). MIT Press.

[4] Blackledge, T.A., Kuntner, M. and Marhabaie, M. (2012). Supraorbital shielding organ in the ogre-faced spider (Deinopis spinosa). Naturwissenschaften, 99(2), pp.145-148.

[5] Nakamura, T. and Yamashita, S. (2000). Learning and discrimination of colored papers in jumping spiders (Araneae, Salticidae). Journal of Comparative Physiology A, 186(9), pp.897-901.

[6] Norgaard, T., Henschel, J.R. and Wehner, R. (2006). The night-time temporal window of locomotor activity in the Namib Desert long-distance wandering spider, Leucorchestris arenicola. Journal of Comparative Physiology A, 192(4), pp.365-372.

[7] Rodríguez, R.L. and Gamboa, E. (2000). Memory of captured prey in three web spiders (Araneae: Araneidae, Linyphiidae, Tetragnathidae). Animal cognition, 3(2), pp.91-97.