Looking at the shooting info you posted I have a couple of suggestions. You have a fairly high ISO for your camera which has introduced noise. If your intent was to go for a silhouette (which it appears you were) then the noise takes away from the shot. Its subtle but a nice noise free image works well for silhouettes.
The shutter speed is a little slow too. Your camera metered this based on the amount of black but you could overide it. If your camera has a manual mode you may want to consider using it for a shot like this. You could also use exposure compensation to help a bit by intentionally underexposing the shot. A faster shutter speed would eliminate any blur produced by the subject and camera shake. (1/4 sec is too slow to handhold especially for this type of shot)
A smaller aperture (like f/8) would also give your silhouette good crisp distinction from the background. It would also help bring the whole body into focus.
You've got some excellent advice in the thread you started (and it's a great way to learn!) but I'll add that I really kinda like it the way it is. Losing the noise would make it a better picture, but I do get a kick out of the waving legs. A good catch.
Your spider almost appears to be waving good-bye to the sun. I like the approach you took for this challenge and I like the results. You must have taken a few shot to get this one. The colour contrast looks great and it suits the shot very well.