I believe that the one on the left works better as a base. The one on the right makes him look like he's got a beer-belly.

Just one problem with that base that I found. You might want to remove the line that separates his body and his backfin. It causes the backfin to look more like a side-fin.

Edit: I made an example of how I might handle it.

Here's a particularly cool-looking seahorse I found while doing a quick search.



Blue and green. I know you're not going to use the picture for anatomical purposes, since this is obviously a more stylistic picture, but you could use the picture to help you figure out how to position your shades. A coloring guide.

In case it matters, a real starfish turning its tail like that would be the equivalent of me twisting my torso around 720 degrees. 

That looks much better. 

Again, you might want to add a little blue to the dark green.

Nah. That's just me being silly as usual

By the perspective thing, I mean that because the "camera" is above the person, the person's lower extremities ought to be smaller. This is also called foreshortening.



look at this image. Notice how the feet are smaller than the hands. This is a product of foreshortening. Because the feet are farther away from the camera than the hands, they appear smaller on the screen.


As for the shading, That isn't so hard to fix. Give your darker shade a blue tint first of all. As things receive less light, they become more blue. Then, try using an even darker color for the underside of the left and right legs. That will help bring you closer to a 3-d effect.