Many alien races inhabit the universe of the Mass Effect game series, with some of them being slightly exotic humans, such as the Asari race, while others are totally foreign, including the jellyfish-like Hanar people and certainly the Krogan race. After all, these races evolved on worlds very different from earth, and it shows.
The Krogan evolved on the harsh jungle world of Tuchanka, in the Aralakh system. Although Tuchanka is now a nuclear desert, the Krogan still retained the evolutionary traits of their jungle-born forebears, and the Krogan are famed for their natural strength and endurance. Commander Shepard met a few Krogan, such as their best friend Wrex, and learned exactly how these scaly aliens work.
The Krogan Have Redundant Body Parts, Including Their Nervous System
The Krogan body is geared toward survival and endurance more than anything, and this means having built-in backup parts in case of an emergency. The Krogan body features secondary and sometimes even tertiary organs, including vital ones, in case the main organs are injured or shut down for any reason. If a Krogan is shot in the heart, a second heart will take over to keep the blood pumping, and if a Krogan's liver shuts down, it's time for the backup to shine. This allows Krogan to survive otherwise fatal injuries, whether or not they have access to medi-gel. The redundancy even includes the nervous system itself. As Urdnot Wrex once explained to Shepard, a backup nervous system allows a Krogan to survive serious physical trauma while experiencing minimal pain. Wrex incorrectly thought that Shepard took advantage of a backup nervous system while dying at the hands of the Collectors.
The Krogan Can See All Around Them
The placement of eyes often reflects on whether an animal is a predator or a herbivore; carnivores have forward-facing eyes with overlapping sight to create depth perception, while herbivores have eyes on the sides of their heads, with little to no overlapping vision. The Krogan, meanwhile, compromise between these two models and have their two eyes spaced close enough for depth perception but far apart enough to widen their overall field of vision. Something that would be in a human's peripheral vision would be squarely in a Krogan's main vision, allowing them to find prey more easily and spot incoming enemies. Very little escapes the sight of a Krogan on the hunt.
A Krogan's Forehead Plate Acts Like A Baby's Bones
During the events of Mass Effect 2, Commander Shepard obtained a tank-born Krogan from Warlord Okeer and awakened it. The perfect Krogan inside assumed the name Grunt and served as a player's first insight into what a young Krogan is like. Not only does Grunt lack scars and folded skin from age, but he has a fractured forehead plate. This is not due to injury; instead, Krogan are born with fragmented forehead plates, and as they age, the plates come together and fuse into a single plate, such as the one on Wrex's forehead. That process is similar to how human newborns have fragmented skeletons whose bones fuse as the baby grows up, including the skull itself.
The Krogan Hump Is A Storage Unit
Unlike humans and other bipedal aliens, the Krogan do not have their heads as the tallest point on their bodies. Instead, Krogan are hunched forward somewhat, allowing them to see other aliens eye to eye, and the tallest part of their body is that hump of theirs. All Krogan have humps, and for a similar reason as camels on Earth: storing food and water for emergencies. This is yet another tool in a Krogan's natural survival kit, and it will allow that Krogan to stay nourished and hydrated even if they are lost in the desert or stranded behind enemy lines. Most likely, every time a Krogan eats or drinks, a part of that intake goes directly to the hump, though it is unclear for how long a Krogan can survive on a fully-stocked hump. This body part also acts as a slang term, such as when an Urdnot scout described clan Weyrloc's members as "tough humps."
Mass Effect has always been renowned for its world-building, but the Krogan may exemplify that. Just one look at their weird and unique anatomy tells players they can expect a fully fleshed-out world. With Mass Effect 4 on the horizon, who knows what we'll learn next about this fascinating warrior race.