Fig. 1. In a liquid environment, after a long initial swim, worms alternate between swimming (A) and quiescence (B). (C) Typical swimming–quiescent pattern for an individual worm. 1, swimming; 0.5, slow swimming; and 0, quiescence (see Materials and methods). At time 0 the worm was transferred from the surface of solid media into liquid. (D) Swimming (gray) and quiescent (black) behavior for typical worms of five species and four C. elegans strains. N2 (Bristol) is the wild-type strain used in this study; the N2 data are from C. (E) Coiled posture in liquid (25°C) of a worm lacking ACh [cha-1(y226ts)]. (F) Sinusoidal quiescent posture of egl-4(ks60) mutant worms.