Krogan are a Race in Mass Effect Andromeda. This page will cover the characteristics of this race.
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 homeworld, but actually thrived in the extreme conditions. Unfortunately, as krogan society became more technologically advanced, so did their weaponry. The end result is that they destroyed their homeworld in a nuclear war that reduced their race into primitive warring tribes.
With the help of the salarians, the krogan were "uplifted" into galactic society, and lent their numbers and military prowess to bring an end to the Rachni Wars. Ironically, after the rachni were eradicated, the rapidly-expanding krogan became a threat to the galaxy in turn, starting the Krogan Rebellions and forcing the turians to unleash the genophage. This genetic "infection" dramatically reduced fertility in krogan females, causing a severe drop in births secondary to prenatal and postnatal death and, ultimately eliminating the krogan's numerical advantage.
Due to the brutality of their surroundings, natural selection has played a significant role in the evolution of the krogan. Unlike most sentient species, krogan eyes are wide-set - on Earth, this is common among prey animals, and in this case it gives the krogan 240-degree vision, giving them greater visual acuity and awareness of approaching predators. Krogan eyes have narrow pupils. Their irises may be red, green, amber, or blue in color.Prior to the genophage, krogan could reproduce and mature at an astonishing rate. Females are known to produce clutches of up to 1,000 fertilized eggs over the course of a year. In present conditions, according to EDI, the odds of a krogan successfully giving birth to two females stand at 1 in 2,000.
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 is said to "hit 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. Younger krogan tend to have looser plates on their head with soft spots in between. When they grow older the plates grow together to form one whole.
Krogan typically stand over 7 feet. Heavy creatures, krogan have been known to weigh at least 150 kilos, upwards of nearly 200 kilos for above-average specimens. Some particularly large krogan weigh in at about 800 pounds (~362 kilos), estimated independently by themselves and by non-krogan observers. 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 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.
Aside from redundant systems, the legendary krogan "blood rage" adds to the race's reputation for being notoriously difficult to kill or incapacitate in normal combat scenarios. In this state, krogan become totally unresponsive to pain and will fight to the death regardless of injury level, with the side effect of reducing their capacity for logic and self-control.
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.
Despite their natural propensity for toughness, krogan do have physical weaknesses. According to Zaeed Massani, if one lodges a knife at a certain spot near the frontal plate on a krogan's head, the plate can be ripped off. It is apparently the one thing krogan do fear.