Despite their soothing purr and natural fluffiness, Tribbles are one of the most dangerous alien lifeforms in the Star Trek universe. At first glance, they are adorable little creatures that seem to have a naturally soothing effect on the human nervous system. A single Tribble is a lovable pet, but bringing one aboard a ship can quickly result in a catastrophic full-scale infestation.
The Tribbles were first introduced in the classic Original Series episode “The Trouble With Tribbles,” in which a single Tribble was brought aboard the Enterprise and, within hours, had multiplied by a factor of hundreds. The resulting horde of Tribbles got into just about every system on the ship. The episode proved one of the most enduringly popular of the original series, and the Tribbles became pop cultural icons, remembered for their cuteness – even though the episode itself culminated with Kirk stood chest-deep in a pile of Tribble corpses.
The reason for their remarkable rate of reproduction is simple – each Tribble is born pregnant. Through asexual reproduction, Tribbles can reproduce with litters of ten every 12 hours… all of whom will then go on to do the same. A single Tribble could therefore have over 1.7 million descendants over the course of three days.
Tribbles are also known for their instinctual dislike of Klingons – and the feeling is very much mutual. As Worf said in Deep Space Nine: “they do nothing but consume food and breed… in a few hours you’ll have ten tribbles, then a hundred – then a thousand!”
Tribbles have popped up now and then after their debut – in Enterprise, Doctor Phlox brings one aboard (albeit in a more controlled manner than the Original Series crew did). In Deep Space Nine’s much-loved “Trials and Tribble-ations,” Sisko and his crew are transported back through time into the events of “The Trouble With Tribbles.” They have even shown up in several recent Star Trek productions, including a cameo by a genetically-modified “attack Tribble” in Star Trek: Picard.