Fig. 4
From: Octopus arm flexibility facilitates complex behaviors in diverse natural environments
Frequency and distribution of arm actions in naturally behaving octopuses. (a) Mean number of occurrences of all arm actions. Percentages above each bar indicate the overall percent occurrence of each action (rounded to the nearest %). Reach, raise, lower, and curl together accounted for 78% of all actions. (b) Mean number of occurrences of arm actions performed by the left versus right arms; arm actions were used with equal frequency on the left (49%) and right (51%) sides of the body (reach: U4 = 302.0, P = 0.844; raise: U4 = 306.5, P = 0.912; lower: U4 = 297.0, P = 0.769; tuck: U4 = 305.0, P = 0.889; curl: U4 = 292.5, P = 0.703). (c) Anterior arms (64%) were used more frequently than posterior arms (36%) for reach (U4 = 172.0, P = 0.006), raise (U4 = 182.5, P = 0.010), lower (U4 = 175.0, P = 0.007), and curl (U4 = 140.5, P < 0.001). (d) Arm pairs 1 and 2 were used more frequently than arm pair 4 for reach (1 vs 4: U4 = 144.0, P < 0.001; 2 vs 4: U4 = 166.5, P = 0.004), raise (1 vs 4: U4 = 171.5, P = 0.005; 2 vs 4: U4 = 130.0, P < 0.001), lower (1 vs 4: U4 = 174.0, P = 0.006; 2 vs 4: U4 = 133.5, P < 0.001), and curl (1 vs 4: U4 = 98.5, P < 0.001; 2 vs 4: U4 = 114.5, P < 0.001), and arm pair 2 was also used more frequently than arm pair 4 for tuck (U4 = 210.0, P = 0.044). Mann-Whitney U tests were used for all comparisons of the occurrences of the top 5 arm actions between: left versus right arms, anterior versus posterior arms, and individual arm pairs (n = 25 octopuses). Error bars indicate standard error of the mean. Asterisks depict statistically significant differences in frequency of actions.
