Conclusion: You picture is well exposed and offered great scope for post-processing. This surely fits the challenge but needed to be more "interesting" to add the punch. Anyway, with three similar submissions in same challenge, this might have suffered from "cliche'" mania. The darkened eye almost give an 'alien' feel :). This certainly is above-average composition which I feel might have been better with deeper DOF and some interesting post-processing.
You have got some amazing photos in your portfolio. "Blue Lagoon" is awesome!
I'm by no means expert in area of photography. My comments are purely based on my limited understanding of technology and art behind digital photography. Apart from doing detailed evaluation of your submission, my intent is to learn different styles of photography by critically evaluating selective submissions. If you've got any questions about this critique, please feel free to contact me via email or PM.
Oh Wow! This is the 3rd turtle shot I've seen and all of them are so AWESOME, unique and "can't-take-your-eyes-off-of-them" amazing! You did REALLY great!!