No one else has commented so i will for you matey.
What can i say?...........
I feel there is a bit too much sharpening which has cause haloing around the edges, just a little, not much. May also be JPEG artifacts adding to it, so if it is then ignore my comment about sharpening
The image seems a little lacking in colour depth. partly because of the grey/brown tortiose and partly because of the green/brown background. They are not a good colour mix, which is a pity really.
I think cutting the tortoise in half is not only cruel, but should be avoided unless you are considering a closer crop or a nice soup.
I can see where you were heading to with the pic and i congratulate you and even encourage you to experiment in this area in the future.
To improve. A closer crop of the tortoises head and less background would make it much better. Remember to focus on what it is you are photographing, remove things unnecessary.
Keep it up and keep sharing.