ASPCK

I hope all those Koopas were humanely raised before they got their shells thrown around in Mario Kart

You also never see a blue Koopa out in the wild, but the Blue Shell is very common.  What's the deal with that? 

I don't know.  Some important questions are left unanswered in the Mario universe.  

So, everybody knows the Koopas.  They come in largely two forms, red and green, and they occasionally have wings.  Very technically, the ones you see walking on the ground are the Koopa Troopas, and the winged ones are Koopa Paratroopas.  They are turtle-like animals with ostensibly removable shells.  The shells are apparently more useful than the rest of the Koopa, since you often see a shell without a Koopa, but not vice versa.  This fact troubles me.  

See, Koopa shells are thrown around all the time in the Mario Kart series.  Green and Red Koopa shells are sometimes distributed three at a time to be tossed wantonly about the race course as weapons.  This leads me to ask what happened to the Koopas who used to be in the shells?  Also, how were all of these Koopas raised before being stripped of their shells?  

There exists a very real possibility that the Koopas are bred in large Koopa mills, subjected to inhumane treatment and given steroids and hormones to promote shell growth.  Then, they're either forcibly removed from their shells and forced to grow a new one, or the much more likely possibility, they are killed for their shells.  This is wholly depressing, and not something that is ever touched upon in Mario canon.  All the more disturbing is the fact that various Koopas are playable characters in the Mario Kart series, forced to throw around the abandoned shells of their brethren. 

I think somebody (Looking at you, Sarah McLachlan) needs to come out in support of the Koopas until we know what actually happens behind the scenes of these Kart races.