Movie 1.

Tail beating patterns of unsegmented and segmented larvae. An unsegmented whole larva swims by means of reciprocal tail beatings. An anterior fragment segmented at 13.4% expresses alternating tail beats (MI = 4), whereas the posterior fragment of the complementary pair expresses irregular (non-reciprocal) movements. Another anterior fragment segmented at −3.1% generates well-patterned movements.