Trill

First appeared:   Stardate 44821.3 / "The Host" [TNG] Type:   Symbiotic humanoids and subterranean invertebrates

Jadzia Dax

The Trill are a joined species comprised of a humanoid host and a small vermiform symbiont that resides in an internal abdominal pocket of the host body. When joined, the Trill incorporates personal traits from both the host and the symbiont, to create a wholly new and unique personality. This personality differs from prior combinations of the symbiont, which is the longest living part of the joined Trill species.

Trill hosts enter voluntarily into their association with the symbiont, and in fact there are is rigorous competition among the potential hosts to determine who will be accorded this honor. Once joined, though, the host and the symbiont becomes biologically interdependent, and after about 93 hours, neither can survive without the other. Also, in the event of danger to the joined Trill, the host will usually be sacrificed in order to save the symbiont.

A Trill symbiont can live for more than 300 years, usually outliving many host bodies. The knowledge and experience of its past hosts, however, is not lost, since the symbiont retains most of it. The body of a Trill host is of a somewhat cooler temperature then that of a normal human, and the brains of the two parts work in combination as one.

The symbionts reproduce in a series of interconnected underground breeding pools that span many kilometers beneath the surface of the Trill home world