A fleaspider was approximately 26 centimeters long, and its brownish-black light fur allowed it be camouflaged as dirt. Its eyes functioned as heat detectors, giving it infrared vision, and ringed its entire body. With its twelve limbs, it had impressive jumping abilities that enabled it to pounce on its prey. A proboscis that extruded from its rear end had a venomous bite, containing a toxin that acted as a metabolic stimulant and an anti-coagulant. As a hemovore, the fleaspider fed on the blood of its victims; once it had bitten its prey it would bleed heavily, and the proboscis drained the blood.
Fleaspider venom was once used for assassination, though it was later primarily used in medicine, to improve a patient's circulation.
Fleaspiders were once common around the Regalian crystal falls, but became almost extinct due to the accidental introduction of Orion emerald finches into their habitats. (Decipher RPG module: Creatures)
In 2373, Julian Bashir asked Quark to import Regalian fleaspiders to Deep Space 9, planning to use their venom to improve Kira Nerys' blood circulation. Quark did not seek a permit for the import of the fleaspiders and also brought in illegal Regalian liquid crystals, which placed both himself and Bashir in legal difficulties with Odo. (DS9 episode: "The Ship")
In 2409 the Vulcan scientist Dr. Sibak had modified Regalian fleaspiders in his Donatu Prime lunar research station. The modified arachnids were now visually indistinguishable from Talarian hook spiders, being six-legged and more than a meter long. The spiders roamed freely on the station and reacted aggressively to intrusion. (STO mission: "Hearts and Minds")