The Voloczin are an octopoidal species of large arachnids, slightly resembling crabs, with a single large eye and eight tentacles. The species evolved in a methane atmosphere of a gas giant, and are comfortable in low-g environments. Possibly due to this, they are apparently rarely seen in the outside galaxy, as some have shown alarm at first sight of them and have no knowledge of them. In addition, Voloczin are capable of seeing thermal images in the visible spectrum, all the better to see through the methane clouds of their homeworld. The Voloczin language involves subtle non-verbal cues (changes in coloration) that a Human would not be able to register, along with sounds beyond the range of typical humanoid hearing. In fact, the syllables Vol, O, and Czin are the only ones humanoids tend to be able to hear or pronounce, with the rest of their names made up of awkward noises and color tones. The difficulty this causes translating Voloczin names for non-Voloczin has led many members of the species to simply identify by the species' name. (TNG novel: Indistinguishable from Magic)
Their insides were mostly gaseous, and when hit by a lethal beam from a phaser they can explode like a burst balloon. (DS9 - Seven Deadly Sins novella: Reservoir Ferengi)
During the 24th century, the chief engineer of the USS Challenger was a Voloczin who went by the abbreviated name Vol, and was the only Voloczin serving in Starfleet at the time. (TNG novel: Indistinguishable from Magic)
A Voloczin worked with Brunt and Gaila in 2377. Gaila wasn't sure if "Voloczin" was its personal name or the name of its species. (DS9 - Seven Deadly Sins novella: Reservoir Ferengi)