Movie S2.

Proprioceptive swimmers characterized by a dimensionless feedback strength χ = 0.12, Reb = 105, ρ = 10, and ma = 0. The quantities u, δ, and λ represent, respectively, dimensionless velocity, feedback delay, and tail amplitude. Midline motions in the vertical direction are rescaled between 0.02 L and –0.02 L.