Fig. 5.
Wild-type animals rotate to align their direction of motion downward when suspended in a solution denser than the animals. A (a–j) 10 images collected at 1 image per second of a young adult, wild-type worm. The red dot indicates the position of the worm’s head. The polar angle varied from 49° in frame (a) to 138.9° in frame (j). (k) The skeletons of the worms in a–j were shifted to align their geometric centers. B The kernel (probability) density estimates of the orientation angle of animals suspended in LUDOX HS-40 suspension (density 1.1 g/mL and viscosity about 7 times that of water) beginning < 2 s after the animals were introduced into the suspension, 5 s later, and 10s later. N0 = 31, N5s = 30, and N10s = 36. In depicting the KDE curves, we used MatlabTM default values. The cartoons depict the average orientation of the animals at the color-coded time