Figure 3

Distribution of deformations among arms of O. bimaculoides. (A) Comparisons of anterior and posterior arm deformations. The number of occurrences of each deformation type (bending, torsion, shortening, and elongation) are plotted with paired bars comparing anterior arm pairs (1 and 2) and posterior arm pairs (3 and 4). Bending was the most common arm deformation: more than 11,000 examples were observed, the vast majority occurring in the anterior arms (X² = 252.56, p = 0.006). Elongation was observed 2,723 times and was seen more often in anterior than posterior arm pairs (X² = 112.40, p = 0.003). Shortening was observed 1,340 times; no significant differences were found in anterior versus posterior arm pairs (X² = 0.34, p = 0.55). Torsion was observed 1,426 times; no significant differences were found in anterior versus posterior arm pairs (X² = 0.74, p = 0.39). (B) Distribution of deformations among all eight arms of O. bimaculoides. Stacked bars depicting the distribution of occurrences of all four deformation types (bending, torsion, elongation, and shortening) for each arm. All deformations occurred more frequently on the right than on the left side of the body (X² = 10.49, p = 0.015), with the exception of the hectocotylized arm in males (R3; p = 0.001). Asterisks indicate significant differences in arm use at p < 0.01.