The Sra'xa'diin  (Species 8472)
Species 8472 is the Borg designation for the Sra’xa’diin (“A Link to the Past” [TFF]), an immensely
powerful alien species native to an extra-dimensional realm known as fluidic space.  They were first
encountered in the Milky Way by the Borg in the year 2373.  (“Scorpion, parts I and II” [VGR]).
The Sra’xa’diin are a highly advanced, biologically unique species.  Their DNA is arranged in a triple helix
formation and is the most densely coded DNA known to the Federation.  This level of complexity gives the
Sra’xa’diin considerable strength, both physically and mentally.  The average individual is telepathic,
tripedal, and stands nearly three meters tall.  They boast an impressive immune system that is able to
destroy any foreign substance that enters the body—and is completely impervious to Borg nanoprobes.  
The immune system can also be used offensively.  Because of their considerable strength and relative
invincibility, the Sra’xa’diin use their claws to overpower any aggressor—and, should they pierce flesh,
the claws infect the aggressor with Sra’xa’diin DNA; the infection spreads quickly, devouring internal
organs from within.  The Sra’xa’diin also emit a bio-electric field that renders them invisible to sensors
and can survive in the vacuum of space.  (“Scorpion, parts I and II” [VGR], “Prey” [VGR]).  There are five
distinct Sra’xa’diin genders.  (“Someone to Watch Over Me” [VGR]).
Physiology
Upon the destruction of the Phobian Republic, the Iconians at long last took action.  Using their advanced inter-dimensional technology, the Iconians sealed the Sra’xa’diin into
fluidic space.  (“A Link to the Past” [TFF]).  It is not known if fluidic space was created specifically for the Sra’xa’diin by the Iconians, or if it was merely a convenient place to
isolate the aliens from the rest of the universe—but the Sra’xa’diin remained within its confines for more than 200,000 years, until the year 2373, when the realm was discovered
by the Borg.

Using a quantum singularity to gain entry into fluidic space from the Delta Quadrant, the Borg considered the newly discovered Species 8472 the apex of biological evolution.  
However, the aliens were impervious to Borg technology, and the invasion of fluidic space provoked a war that provided the Borg with the first true threat they ever face.  After
driving the Borg from fluidic space, Species 8472 followed them into the Delta Quadrant and began the systematic destruction of Borg space.  Billions of drones, hundreds of Borg
ships, and dozens of planets were completely obliterated while Species 8472 lost only a few bioships.  However, Species 8472 soon retreated to fluidic when the crew of the USS
Voyager devised a weapon capable of defeating their bioships.  (“Scorpion, parts I and II” [VGR]).

Amidst the chaos of the retreat, one Sra’xa’diin was left behind in the Delta Quadrant.  It survived, alone, for several months before being discovered by the Hirogen—who
relentlessly hunted the alien, believing it the ultimate trophy.  In mid-2374, the alien was briefly rescued by the crew of the USS Voyager, but ultimately fell back into the hands
of the Hirogen.  (“Prey” [VGR]).

Upon their defeat, the Sra’xa’diin became convinced that humanity would soon invade fluidic space.  In preparation for the attack, they established several terraspheres in the
Delta Quadrant to serve as training grounds for potential infiltration/invasion of the Federation.  Using advanced genetic manipulation techniques, the Sra’xa’diin were able to
modify themselves to appear human, and were in the initial planning stages of their venture when one of the terraspheres was discovered by the USS Voyager in 2375.  The
Voyager crew was ultimately able to convince the Sra’xa’diin that the Federation wished them no harm, going so far as the provide the Sra’xa’diin with the specifications to the
weapon used to defeat them.  Satisfied with the outcome, the Sra’xa’diin again returned to fluidic space.  (“In the Flesh” [VGR]).

After that encounter, the Sra’xa’diin remained unseen 2395, when the crew of the USS Starlight discovered the bioships that crashed on Aurillac VII during the culling of the
Phobian Republic.  Much to their surprise, one of the pilots was still alive—and eager to rejoin its people.  Aware of the truce between the Sra’xa’diin and the Federation, the
alien used the fleet of bioships beneath the surface of Aurillac VII to fend off a Romulan invasion before finally retreating to fluidic space.  (“When the Shadows Steal the Light”
[TFF], “Aftermath” [TFF]). The Sra’xa’diin have not been seen since.

In 2397, another derelict bioship was discovered in the M’Kieru Sector near the intersection of Federation, Romulan, and Klingon territory.  While the Klingons worked with the
Federation to capture the ship, the vessel was hotly contested by the Velora and the Garidians, who traveled from afar to stake a claim to the bioship.  After much political
maneuvering, the bioship was ultimately destroyed amidst a three-way fight between the Klingons, the Garidians, and the Velora.  (“Ring of Fire, parts I and II” [TFF]).  
A highly xenophobic race, virtually nothing is known about the Sra’xa’diin culture—or if they even have a
culture.  They consider themselves superior to all other life forms, and believe that lesser species must
be purged.  (“Scorpion, parts I and II” [VGR]).  Federation scientists have also learned a next to nothing
about the Sra’xa’diin language.  The most complex language known to exist, it is believed that no
humanoid species has the mental capacity to comprehend it.  (“Ring of Fire, part I” [TFF]).
Culture
History
The Sra’xa’diin were genetically engineered by the Phobian Republic approximately 201,000 years ago to
serve as warriors in an ongoing war with the Al-Bhed.  They were engineered from a mysterious space-
dwelling organism—a bioship—the Phobians discovered in the Sra’xa’diin Nebula several years prior, and
successfully eliminated the Al-Bhed after only a few months in service.  The Phobians subsequently
enjoyed a few months of peace, but soon discovered they had not the ability to control their creation.  
With the Al-Bhed no longer a viable threat, the aliens—now called the Sra’xa’diin—began to target the
Phobians.   (“Reconciliation” [TFF], “A Link to the Past” [TFF], “Words Better Left Unspoken” [TFF]).  

Hoping to quell the Sra’xa’diin uprising, Phobian Ambassador Phannah contacted the Iconian
Confederacy for assistance.  The Iconians dispatched Professor Eridor to the Phobian Republic, who was
initially receptive to the Phobians’ plight.  However, upon learning the Sra’xa’diin problem was
engineered by the Phobians themselves, Eridor officially withdrew Iconian support.  Without Iconian
intervention, the Sra’xa’diin were able to annihilate the Phobian Republic in a few short months.  
Desperate to gain some sort of advantage, the Phobians set a trap for the Sra’xa’diin in the Veriius Belt.  
This resulted in the destruction of several bioships, and forced several more to crash on Aurillac VII—but
these efforts were insufficient and the slaughter continued—culminating in the Massacre of Xantoran VII,
where all but a handful of the Phobian people were slaughtered by the Sra’xa’diin.  (“When the Shadows
Steal the Light” [TFF]), “Reconciliation” [TFF], “A Link to the Past” [TFF]).
Species 8472 bioships attack (click images for higher resolution images)