Fig. 6
From: Octopus arm flexibility facilitates complex behaviors in diverse natural environments
Frequency of arm deformations for each arm region (proximal, medial, distal). (a) The mean number of deformations were unequally distributed within each part of the arm: distal (47%), medial (35%), and proximal (18%) (One-way ANOVA, F2 = 27.79, P < 0.001). Tukey’s post hoc tests showed that the distal part of the arms performed a greater number of arm actions (M = 126.1) than the proximal (M = 49.48, adjusted P < 0.001) and medial parts of the arms (M = 95.28, adjusted P = 0.011) and the medial part of the arms performed a greater number of arm actions than the proximal part of the arm (adjusted P < 0.001). (b) Bending was unequally distributed within each part of the arm (Kruskal-Wallis one-way ANOVA, H2 = 50.88, P < 0.001). Dunn’s multiple comparison tests (two-sided) indicated that bends occurred most frequently in the distal part of the arm (M = 107.0), followed by the medial (M = 63.20, distal vs medial adjusted P = 0.027) and then the proximal (M = 19.28, distal vs proximal adjusted P < 0.001; medial vs proximal adjusted P < 0.001) parts of the arm. Shortening occurred more often in the medial part of the arm (M = 7.60) than in the distal part of the arm (M = 3.4, adjusted P = 0.025); elongate occurred more frequently in the proximal (M = 24.52) and medial (M = 22.16) parts of the arm as compared to the distal (M = 11.48) part of the arm (proximal vs distal adjusted P < 0.001; medial vs distal adjusted P = 0.003); torsion was not observed in the proximal part of the arm and occurred significantly more often in the distal (M = 4.28, adjusted P < 0.001) and medial parts of the arm (M = 2.32, adjusted P < 0.001). Different letters indicate statistically significant differences between arm regions (n = 25 octopuses). Asterisks depict statistically significant differences.
