Simple but creative concept.

it is a good photo but i would not figure out what it is if i did not see the name of the contest
sorry

looks very much like from a "Science" book, under the microscope type of picture

Add some shading to the body.

where

Add the shading on the opposite side of the light source as it is reflected in the eyes (pretend you are shining a flashlight on the eyes - the shading will go on the other side of where the flashlight lands on your subject.

You can also add some gradual shading to the legs to make them look more rounded. This might help some: http://artswork.asu.edu/arts/students/line/line4.htm

1) select the green body using "magic wand"
2) use "dodge" for highlights (lighter part of the body towards the light source)
3) use "burn" for shadows (darker part of the body)

add simple bumpy texture to body:
1) add "noise" (not too much, need to experiment)
2) add "blur", "gaussian blur"

add depth for water background:
1) select the water area
2) choose a darker blue, use "paintbrush" paint at the bottom portion of the image
3) add alittle "noise" , then a little "motion blur", then add "ripple" or "wave" (under "distort" to taste

Hope this helps, of course there are more methods that can be used... do some exploring online photoshop tutorials

now its better aheman?