I like the colour scheme and the tortoise stands out from the background. I didn't see this fellow when I was there last year.

The comment about sharpness is because a small portion at the front is not in focus.

I am describing the technique to be adopted in these situations:

1) first stop down,
2) then press and hold the Depth of field Preview button
3) then move the focussing ring to bring the front portion into focus and see if the eye potion is in focus or not. If the eye portion is not in focus then stop down the aperture i.e make the aperture narrow from f5.6 to f8 to f11 etc till you find both the front portion and the eye in focus.

After this you know the aperture to get the right depth of field. Now we have to see if the shutter speed is high enough to give us a shake free picture. If not, then you have to decide on increasing the ISO, using mirror lock up etc.

Cheers,
Sabyasachi