Quarians

The quarians are a nomadic species of humanoid aliens known for their skills with technology and synthetic intelligence. Since their homeworld Rannoch was conquered, the quarians live aboard the Migrant Fleet, a huge collection of starships that travel as a single fleet.==Biology [1]==

Quarians are generally shorter and of slighter build than humans. Quarians have an endoskeleton, lips, teeth, and two eyes with eyelids and tear ducts. Their ears or ear analogues differ in a noticeable fashion from those of humans, with references made to "what [passes] for the quarian version of an ear". Their eyes can see into the ultraviolet end of the spectrum; their suit HUDs can show information in those wavelengths. Quarian facial structure and hair actually makes them the most similar to humans in physical appearance.They also have three thick fingers on both hands which include a thumb, an index finger, and a long finger, similar to the middle fingers for humans, as well as three toes on each foot. Their lower legs are bowed backwards significantly, compared to humans. Aside from hands and legs, their general body shape and sexual dimorphism is similar to humans. Male quarians, however, appear to lack a third toe. Like humans, quarian blood is red.

The most distinguishing feature of quarian biology is their weak immune system, compounded by centuries of living in sterile environments. As a result, all quarians by necessity dress in highly sophisticated enviro-suits, to protect them from disease or infection if they are injured. Their suits can be compartmentalized in the event of a tear or similar breach to prevent the spread of contaminants (similar to a ship sealing off bulkheads in the event of a hull breach). Along with their suits, quarians also have extensive cybernetic augmentations integrated into their bodies. A quarian's lifespan is roughly equal to a human's, but is prone to be less if infection breaks into the suit.

Quarian immune systems have always been relatively weak, as pathogenic microbes were comparatively rare in their homeworld's biosphere. Furthermore, what few viruses and other microbes were native to their homeworld were often at least partly beneficial to them, giving them a symbiotic relationship with their environment. After living aboard the Migrant Fleet for generations, the quarians' immune systems have atrophied further still due to the years in the sterile environment of the Migrant Fleet. As such, quarians are given various vaccinations and immunizations to help ward off disease. However, they prefer the safety of their suits even in clean environments and are reluctant to remove them without a good reason.

The quarians are a dextro-protein species of reverse chirality from humans. The food of levo-protein races such as humans is at best inedible and at worst poisonous, most likely triggering a dangerous allergic reaction. Quarians who want to taste something (other than the refined edible paste issued to all who leave on their Pilgrimage) can eat specially purified turian cuisine, though the typical quarian diet is vegan, as livestock were found to possess an inefficient resource-to-calorie ratio when stored on the Migrant Fleet.

Other than the oft-mentioned maladjusted immune systems, the quarians have a surprisingly robust physiology.