Coral Reef Color

National Geographic's Web site has a terrific feature with multi-media presentations on the colors of the reef:

Gaze at the vivid yellows, blues, and psychedelic swirls of a single emperor angelfish and you'll sense the whimsy of evolution. Go on to explore its home in lush coral reefs and you'll soon hit sensory overload, assaulted by colors and patterns that range from sublime to garish. Coral reefs are unquestionably the world's most colorful places. But why?

Go to the site to find the answer(s).