Realistic robotic fish

At the Expo FC 2010 in Japan, Osaka University presented a pretty mind-blowing prototype of a robotic fish. Its movements in particular are so realistic you could easily mistake it for a real fish. It measures 10 cm in length, is powered by a solid polymer fuel cell (Power Tube) and a polymer lithium battery. Its hinged fin allows it to move forward; the fish also has a mobile center of gravity which enables it to dive or swim to the surface. Video demonstration: (you'll swear it's real!) http://www.youtube.com/watch?v=bVTpINHJeaY