Because these designs of mine are clearly not teenagers nor ninjas. These are my interpretation of the TMNT’s characters, in which I tried to incorporate a lot of elements from different species of real turtles, and Japanese attire, while still maintaining individual personalities of the turtles. I also tried to make the Shredder a bit more Japanese, and Krang a bit more like a modern android. I will continue doing other characters later.

You can see the sketches here https://www.facebook.com/hahuyhoang.art/photos/pb.471650312872103.-2207520000.1404894666./701157753254690/?type=3&theater