Fig. 5
From: Octopus arm flexibility facilitates complex behaviors in diverse natural environments
Frequency of arm deformations used for each arm action in naturally behaving octopuses. Overall, bend was the most frequently used (70%) followed by elongate (22%), shorten (6%) and torsion (2%). (a) Mean number of bends used for each action; bends were used with equal frequency for all arm actions (Kruskal-Wallis one-way ANOVA, H11 = 9.895, P = 0.540). (b) Mean number of shortenings for each arm action; the shorten deformation was used more frequently for some arm actions than others (Kruskal-Wallis one-way ANOVA, H11 = 147.1, P < 0.001). Dunn’s multiple comparison tests (two-sided) indicated that reach, raise, lower, tuck, and curl used shorten more often than push, parachute, roll, grasp, stilt, and tiptoe (P < 0.05, see Table S1 for specific Z-scores and P-values). (c) Mean number of elongations for each arm action; the elongate deformation was used more frequently for some arm actions than others (Kruskal-Wallis one-way ANOVA, H11 = 129.7, P < 0.001). Dunn’s multiple comparison tests (two-sided) indicated that reach, raise, lower, and curl used elongate more often than push, parachute, roll, grasp, stilt, and tiptoe (P < 0.05, see Table S2 for specific Z scores and P values). (d) Mean number of torsions for each arm action; some actions used torsion more often than others (Kruskal-Wallis one-way ANOVA, H11 = 142.0, P < 0.001). Dunn’s multiple comparison tests (two-sided) indicated that the arm actions reach, raise, lower, and curl used torsion more often than push, parachute, roll, grasp, stilt, and tiptoe (P < 0.05, see Table S3 for specific Z-scores and P-values). Error bars indicate standard error of the mean. Different letters indicate statistically significant differences between arm actions (n = 25 octopuses).
