Rutan

The Rutan Host were a race of amorphous green blobs who waged a war with the Sontarans which has lasted for 50,000 years (DW: The Poison Sky).

Physical characteristics
Rutan host are amphibious and native to the cold planet Ruta III. They have trouble dealing with warm environments. (DW: Horror of Fang Rock)

In their natural forms, the Rutans (singular Rutan) are shaped somewhat like jellyfish, with a green, glowing body and many light-green tendrils. They are amphibious and can cling to sheer vertical surfaces, with considerable mobility out of the water despite their shape. Rutans can also generate lethal biolelectrical shocks able to kill Humans (and probably Sontarans), and seem to be able to absorb electrical energy directly for sustenance. They reproduce by a process similar to binary fission, with each daughter Rutan carrying the memories of the parent. (DW: Horror of Fang Rock).

Rutans can see, even without visible eyes, but their vision is limited and monochromatic. (DW: Horror of Fang Rock)

Rutans can speak by forming vocal apparatus (PDA: The Infinity Doctors), The Rutan observed in Horror of Fang Rock spoke with a harsh, tinny male voice. (DW: Horror of Fang Rock).

Culture
The Doctor described the Rutans as "infinitely adaptable" (DWM: Pureblood).

Rutans never refer to themselves as individuals, preferring the first person plurals "we", "us" and "our(s)". Its seems they also have no individual names. (DW: Horror of Fang Rock onwards).

The Rutan hive mind is co-ordinated by a Queen who lives on Ruta III. Without her influence the Host would fall apart. (NA: Shakedown)

Military tactics
Rutans are able to operate independently (and like the Sontarans, often dispatch scout units consisting of a single soldier), but they do not see individuals as important and all individual desires are subsumed by the general desire to win the war with the "Sontaran rabble" (as they often unflatteringly call them).

They often use shapeshifting technology to adapt to alien environments and infiltrate alien cultures; Rutans are consummate spies. A Rutan usually kills specific individuals and then impersonates them. (DW: Horror of Fang Rock, DWM: Pureblood)



Technology
The Rutan Host have unknown types of technology, though they are apparently less advanced than the Sontarans. Rutan spaceships are crystalline in structure and have the appearance of glowing balls of fire. These ships can control the weather to a degree. Individual Rutans can also shapeshift into other forms, but they need to know this form very well, usually after careful study and dissection. This skill was discovered and implemented in the early 1900s. (DW: Horror of Fang Rock)

Rutan biotechnology
Circa 1880 in England, Percival Ross managed to obtain Rutan healing salve and experimented with its ability to merge together normally incompatible kinds of animal tissue, creating hybrids. (MA: Evolution)

Rutan biotechnology is sufficiently advanced to "uplift" a species to sentience. By the 26th century, they had done this at least once, on the planet Sentarion, where they are worshipped by the insectoid Sentarii as "the Shining Ones". (NA: Shakedown)

History
The Rutan Host has been engaged in war with the Sontarans for 50,000 years (DW: The Time Warrior onwards).

The two species had a brief alliance during the Millennium War. (PDA: The Quantum Archangel)

As mentioned, in 1880, a human found and experimented with Rutan biotechnology. (MA: Evolution)

Though the Rutans originally controlled most of Mutter's Spiral, by the 1900s, they were starting to lose the war and were forced to retreat to more fortified locations. During this time period, a Rutan scout landed on the coast of England and took over the Fang Rock lighthouse while attempting to assess the planet's usefulness as a base to fight off the Sontarans. All their actions have been to advance the war, such as scouting out new planets to use as bases. (DW: Horror of Fang Rock)

During the Rassilon Era, the Rutan Host and the Sontaran Warburg convened on Gallifrey to make diplomatic overtures. (PDA: The Infinity Doctors).


 * We do not know when the Rassilon Era took place, relative to the history of Earth or other worlds. Also, we do not know when this conference took place relative to events in the known history of the Time Lords, such as the Sontarans' brief invasion of Gallifrey.

The Doctor has stated, perhaps jokingly, that his money is "on the Rutans" when it comes to the Rutan-Sontaran war.