Spice spiders, also known as energy spiders, were a type of arachnid indigenous to the Spice Mines of Kessel. Deep within the pitch-black caves of these mines, they spun webs from glitterstim, a scarce and valuable spice. To capture their prey, these spiders would project webbing from their mouths, using it to ensnare and impale victims before draining their life force. Bogeys were a favored food source, as their pure energy caused a reaction in the glitterstim, producing light that alerted the spiders to their presence. The spiders' aversion to bright light stemmed from their adaptation to the darkness of their cave habitat. However, they were attracted to the light generated by the glitterstim-bogey interaction, sometimes mistaking other light sources for it. They posed a significant danger to spice miners, particularly those who ventured too far into their territory. Kessel's administrators often used assignments to these deep tunnels as a permanent solution for troublesome prisoners. Because energy spiders subsisted on energy, blaster fire proved ineffective, with the energy simply being absorbed. In contrast, ion weapons, which disrupt energy distribution, were surprisingly effective (though non-lethal) against them.
During an investigation into ground tremors on behalf of Lando Calrissian, the owner of the spice mining operation, Han Solo and Leia Organa Solo discovered a unique subspecies of energy spider. This new variant, distinguished by its reddish coloration and the absence of hooks and spines on its arms, was named the "red spider". These spiders were herbivorous, consuming the giant fungi found in the lower levels of the Kessel mines. Furthermore, they possessed a poisonous effect on the standard energy spiders, enabling the two species to coexist. While the two types were genetically compatible and capable of interbreeding, no records documented such occurrences or their outcomes.
When fed ryll, energy spiders would produce glitteryll and experience significant growth in size. Some of these creatures were smuggled to Ryloth, one of the few planets besides Kessel capable of sustaining them. Following the establishment of the New Republic, a few energy spiders were brought to Coruscant for the Coruscant Livestock Exchange and Exhibition, where they were displayed in the arthropod exhibit alongside toxin/adrenaline-producing orbalisks and Death Seed-producing drochs.