Krogan

"Admiral, you must forgive the Krogan for being so prone to aggression, their primary instinct is fight back or die. It can be to our advantage once we establish a are all use to each other." ~Unknown siren officer.

Krogan are a highly intelligent reptilian race who are from a hostile planet that made them tough. They have twice as many organs as humans and are incredibly strong. In the galaxy they have not been seen often in the main timeframe war except in the most elite assault forces and as mercenaries. They where seen more during post war.

Due to how densely built Krogan are they usually sink in water and rely on walking on the ground when in water without  special gear such as a water jet suit and/or a buoyancy layer in their under armor to help them swim. Although a large number of Krogan have been assigned to work in the elite new amphibious special forces fleet of Swims Like Shark during the time the NGR was promoting him among their ranks to admiral. This was possibly to insure land operations did not remain the fleets point of weakness due to the Siren main crew body being better suited for wet combat then terrestal combat.

During the invasion of the Ptranosaurians even more Krogan where seen in action as a attempt to stand a chance againced the Ptranosaurian ground and boarding forces who where huge strong and nimble insanely well trained death machines. But due to the Ptranosaurians better technology, and their ancient cellular immortal life experience yielding them even better training, and their ability to fly and breath fire being the final nail in the coffin, even the Krogan failed to match them. However after the Ptranosaurian invasion the Ptranosaurians never forgotten them, and had cured the Krogan of their sterilization, believing they could deal with the Krogan birth rates the same as with the even swifter breeding Yush'shy'R who they simply insure always have enough homes and freedom to express their culture and have their own independent military. To them the possibility of Krogan needing to coop with their birth rate is inconsaquncal as they may one day only use it as a means to conquer a 3rd galaxy.