This is definitely an illusion. Tortoises don't move that fast. Well captured. A little more space in front of him/her and a more natural background might help with impact.
Difficult background to do longer exposures. Longer exposure backgrounds should be black or as dark as possible to avoid other exposures from light colored objects
Really a cute idea, I understand your thinking......and I get it!! The background blue is too over powering for me. I know that sometimes you don't have a lot of choice. Good plan-attempt and it almost works. Nice try.