Maybe it's intentional, but the tail looks much too heavy. It only looks remotely natural during transitions where it starts to dive. The motive tail is providi

Maybe it's intentional, but the tail looks much too heavy. It only looks remotely natural during transitions where it starts to dive. The motive tail is providing significant lift. As a later commenter (ibnjmn) mentions... it looks like the center of gravity is too far back. Maybe they designed this so that the robo-fish could stop quickly, but it certainly doesn't look efficient for something that is nominally neutrally buoyant.