In the fictional universe of Star Trek, "Species 8472" is the name (designated by the Borg) of an advanced alien race that lives in the realm of fluidic space.

Anatomy

They have a dense genetic structure with triple-helix DNA and a powerful immune system. Their anatomy is unique in that they possess three legs and communicate exclusively through telepathy. Their species is composed of five different sexes who own separate sections of the fluidic space realm that they live in. Their technology, including starships and weapons, is mainly biological.

Technology

Species 8472 possesses a biologically-engineered ship known as a bioship. This ship is capable of melting itself through various surfaces, like that of a Borg vessel or a starship. If the weapons of one bioship are linked with that of 6 or 7 others, the bioships have the capability of wiping out an entire planet.

History

Species 8472 were discovered by the Borg—who were unable to assimilate them—in the 2370s. This was because the species had the capability of repelling anything in their bodies that was foreign to their cells. This invasion of their realm provoked a war, the first real threat the Borg faced in thousands of years, wiping out trillions of drones.

The 8472s were forced to retreat when the crew of the starship Voyager armed warheads with modified nanoprobes, capable of killing the 8472s.

When they retreated back to fluidic space, one member was left behind, and was relentlessly hunted by a group of Hirogen for several months.

Concerned about the threat posed by humanity, the 8472s built a space station in normal space and recreated Starfleet Academy within, as a training ground for potential infiltration. The plan was uncovered and stopped by the crew of Voyager who convinced the 8472s that The Federation had no quarrel with them.

It has been speculated that Species 8472 were the creators of the alien parasites featured in the Star Trek: The Next Generation episode, Conspiracy. This unproven theory would explain how the 8472s obtained sufficient intelligence on humanity to recreate Starfleet Academy.