Krogan

The krogan are a species of large reptilian bipeds native to the planet Tuchanka, a world known for its harsh environments, scarce resources, and overabundance of vicious predators. The krogan managed to not only survive on their unforgiving home world, but actually thrived in the extreme conditions. Due to the brutality of their surroundings, natural selection has played a significant role in the evolution of the krogan. Unlike most species on the Citadel, krogan eyes are wide-set - on Earth this is distinctive of prey animals, but in this case it gives the krogan 240-degree vision, giving them greater visual acuity and awareness of approaching predators. Prior to the genophage, krogan could reproduce and mature at an astonishing rate. Their large shoulder humps store fluids and nutrients, enabling them to survive extended periods without food or water. A bigger shoulder hump is seen as a sign of high status, showing how successful an individual krogan is at hunting. Their thick hides are virtually impervious to cuts, scrapes or contusions, and they are highly resistant to environmental hazards, including toxins, radiation, and extreme heat and cold. Consequently their diets can include food and drink which would prove very dangerous to other species—a fact reflected in the krogan liquor of choice, ryncol, which "hits aliens like ground glass". Younger krogan have yellow or green markings on their hides. These markings darken to brown or tan over time, showing their age. Krogan typically stand over 7 feet and weigh roughly one ton in armor. Biotic individuals are rare, though those who do possess the talent typically have strong abilities. The most amazing physiological feature of krogan biology is the multiple instances of major organs. These secondary (and where applicable, tertiary) systems are capable of serving as back-ups in the event of damage to the primary biological structures. They have, for example, two hearts, four lungs, and most notably four testicles. This reflects in their slang, where they often speak about a "quad" where a human would use the words "balls" or "pair". Krogan also have a secondary nervous system using a neuroconductive fluid, meaning they are almost impossible to paralyze. Krogan bleed a yellow or orange fluid when shot, which may be this fluid or actual blood. Having redundant systems makes krogan difficult to kill or incapacitate in normal combat scenarios. Sheer physical hardiness means an individual krogan can expect to live for centuries. Krogan can live for well over a thousand years, as evidenced by Warlord Okeer, a veteran of the Krogan Rebellions who died (of decidedly unnatural causes) well over a thousand years after the Rebellions ended.