question:  How were Jig and Bucky attacked by the Vapor snakes?
context: The Blue Behemoth By LEIGH BRACKETT Shannon's Imperial Circus was a jinxed space-carny leased for a mysterious tour of the inner worlds. It made a one-night pitch on a Venusian swamp-town—to find that death stalked it from the jungle in a tiny ball of flame. [Transcriber's Note: This etext was produced from Planet Stories May 1943. With Shannon's Imperial Circus, the Greatest Show in Space, plastered so thick with attachments...." I've wet-nursed Shannon's Imperial Circus around the Triangle for eleven years, and I know. Nobody insults Buckhalter Shannon's Imperial Circus to Buckhalter Shannon's face unless he's tired and wants a long rest in a comfy fracture-frame. Bucky Shannon sighed, and let his fist start traveling, a long, deceptive arc. It knocked him sideways and down, and the little dark men jumped up, quivering and showing their teeth. Mistaken identity." It was the most complete dead-pan I ever met, and you couldn't see into those innocent blue eyes any more than you could see through sheet metal. It has always been my desire to lighten the burden of life for those less fortunate...." "There are many towns along the Venusian frontiers where no entertainment of the— proper sort has been available. It was Gow, our zoo-man—a big, ugly son-of-a-gun from a Terran colony on Mercury. His hands, holding the curtains apart, had thick black hair on them and were not much larger than the hams of a Venusian swamp-rhino. "Gertrude be blowed," growled Bucky. The only other one on the Triangle belongs to Savitt Brothers, and she's much smaller than Gertrude." The mystery surrounding the origin and species of the cansin is a fascinating subject. I said tactfully, "We'd have to have at least a hundred U.C.'s." He dragged out a roll as big as my two fists, peeled off half a dozen credit slips, and laid them on the table.
output:  They had been released by someone on purpose
options:  They had been released by someone on purpose  Bucky had released them while inebriated  They had gone into the wrong enclosure.  They had escaped their tanks in search of food.