Species 8472 is undoubtedly one of the most bizarre organic lifeforms ever encountered by the Federation. Their origins lie in ‘fluidic space’ – a higher dimension which is apparently composed liquid rather than the empty space of our own universe.
Their dense body structure is highly resistant to many forms of energy such as transporters and weapons. They are also telepathic which they use to great effect in scanning the minds of other races and using it as a form of tracking mechanism when hunting enemy starships.
The species are different from others using highly advanced organic technology. Their bio-ships are composed of the same biological material as themselves, and thus shared both their resistance to technology and their vulnerability to modified nanoprobes. Their bio-lasers have absolutely no problems in penetrating Borg shields and completely destroying each cube.
The Borg encountered Species 8472 in 2373, after finding their way into fluidic space to search for more species worthy of assimilation. The species proved immune to assimilation and the invasion of their realm provoked a war; according to Seven of Nine, Species 8472 was the first species to offer “true resistance to the Borg” in their long history.
“The weak will perish.”
– Species 8472, 2373 (“Scorpion”)
With their superior biological technology, Species 8472 drove the Borg back and launched a counter-invasion of the galaxy, annihilating large numbers of Borg drones, ships, and even planets.