Energy spiders or spice spiders were arachnids that inhabited the spice mines of Kessel. They lived in complete darkness inside the mine's caves spinning webs made of Glitterstim, a rare kind of spice. The spiders would shoot webbing from their mouths to capture prey, impale them and then quickly suck the life energy from them. The spiders were known to feed on bogeys, as they were sources of pure energy that caused the glitterstim to react and produce light, alerting the spiders to their presence. The spiders also disliked bright light, since they lived in pitch black caves. Energy spiders were, however, drawn to the light produced by the glitterstim-bogey interaction, and there are even cases of mistaking other lighting sources for this interaction. They were one of the many threats faced by the spice miners, especially those who wandered too deep into the caves where the spiders lived. Often, the administrators and superiors on Kessel would send disruptive prisoners to work in these deep tunnels, ensuring an often permanent solution to a prisoner problem. As energy spiders feed on energy, blaster bolts are ineffective against them and are merely absorbed. Curiously, ion weapons, since they affect energy and its distribution, are highly effective (but not lethal) against them.
A variant sub-species of energy spider was discovered by Han Solo and Leia Organa Solo while investigating a series of ground quakes on behalf of Lando Calrissian, owner of the spice mining operation. The newly discovered subspecies had a reddish hue and lacked the hooks and spines that are present on the arms of typical spiders. These "red spiders" were found to be herbivorous, feeding on the giant fungi found in the lower reaches of Kessel's spice mines. These red spiders had a poisonous effect on baseline energy spiders, allowing the two to coexist. Genetically, the two different types could even mate, though no documentation of the act nor results existed.
When fed ryll, the energy spiders would produce glitteryll and grow to large sizes. A number of the creatures were smuggled onto Ryloth, which proved to be one of the few other worlds capable of supporting them. A few made their way to Coruscant for the Coruscant Livestock Exchange and Exhibition following the establishment of the New Republic in its arthropod exhibit, along with toxin/adrenaline-producing orbalisks and Death Seed-producing drochs.