Undulation sucks eel-like swimmers through water

Video by John O. Dabiri

Video of a lamprey (black outline) swimming in a water tank. Colors indicate low-pressure suction forces (blue) and high-pressure pushing forces (red) generated by the animal as it swims. Colorbar indicates pressure in units of Pascals (Newtons per square meter). Playback is approximately 1/60 of real time.