Galactic historythe Vorcha are a very violent race who are from a planet that is firstly small and secondly extremely overcrowded. They are given very low regard as an intelligent race among the other organic races of the galaxy and are mainly looked at as slum rats or Vermin rather than an intelligent race, and the only other race willing to interact with them or use them for anything are the Krogans.
This mainly because of the fact that the Vorcha, being a highly adaptable species that can pretty much live on anything while reproducing at pre-Genophage Krogan levels are the perfect soldiers for any Mercenary band, which is pretty much the main trade of the Krogans who cannot reproduce quickly anymore.
Vorcha are very rarely seen outside of the lawless Terminus Systems because that is pretty much the only place where they are accepted anyway. They themselves are not a space-faring race, but were rather introduced to the galactic scene as stowaways on visitor vessels to their homeworld. The Krogans regularly go to the Vorcha homeworld to recruit Vorcha to add to their Arsenal of Mercenaries.
 Culture and Biology
The main reason for many of the problems on the Vorcha homeworld lie with the unfortunate fact that while Vorcha reproduce very quickly, they are also a very primitive and aggressive race. An average Vorcha only lives for around 20 years at the most and spends most of it living in tight clan based life fighting lots of wars with other Vorcha clans or with whichever Mercenary Band they decide to join.
For the Vorcha inflicting and receiving pain is a way of life and they grow stronger for it. Most younger Vorcha are constantly in fights or brawls in order to get stronger and more ferocious for future fights. There are very few Vorcha who ever decided to bend from the norm and become anything other than a fighter or mercenaries. since most of the time they are fighting each other for more resources on their homeplanet
Biologically, the Vorcha have a unique set of cells that are not found in any other intelligent race of the galaxy. Their cells are more akin to Earth's Planarian worms, with their bodies being made of clusters of non-differentiated cells. This presents them with a unique set of abilties that really help with their violent and survival oriented nature. Vorcha can adapt to nearly any enviroment and planet. Their biology adapts at a phenomenal rate on an individual level and not even at a generational level. For example a Vorcha living in an Oxygen based enviroment can change their system to adapt to a Methane based enviroment if the need came. However they are usually limited to one enviromental change in their lifetime. They can also grow thicker skin and heavier skeletal structures from getting inflicted by injuries and can also adapt to differing gravitational forces by growing more stronger muscles. A very interesting adaptation that helps with their combat nature is that when they lose a limb they can actually regrow it over a period of months stronger than before.