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First published online September 19, 2006
Journal of Experimental Biology 209, 3697-3707 (2006)
Published by The Company of Biologists 2006
doi: 10.1242/jeb.02435

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Locomotion by Abdopus aculeatus (Cephalopoda: Octopodidae): walking the line between primary and secondary defenses

Christine L. Huffard

Department of Integrative Biology, University of California, Berkeley, CA 94720-3415, USA

View larger version (51K): [in a new window]   Fig. 1. Examples of body positions during: (A) jetting, (B-D) swimming, (E) walking and (F-M) crawling by a variety of octopuses, in which all except A show movement from the left to right side of the page. (A) Hapalochlaena lunulata jetting vertically up and down in the water column, drawn from the video Shape of Life: Survival Game Sea Studios, Inc., cameraman Bob Cranston. (B) Thaumoctopus mimicus swimming slightly above the substrate, drawn from a frame of a video taken by Annie Crawley (damaged arm I idealized, but missing arm not created). (C) H. lunulata swimming in the water column, drawn from photograph by R. L. Caldwell. (D) Octopus sp. 18 (Norman, 2000) swimming close to the substrate, drawn from photograph by Roger Steene (Norman, 2000). (E) Amphioctopus marginatus drawn from the video Shape of Life: Survival Game Sea Studios, Inc., cameraman Bob Cranston. (F) H. lunulata drawn from a photograph by R. L. Caldwell. (G) Octopus cf. sp. 18 (Norman, 2000) drawn from photograph by Jeffrey Rosenfeld. (H) Octopus sp. 2 (Hoover, 1998) drawn from photograph. (I) Callistoctopus luteus, drawn from photograph by Roberto Sozzani. (J) Octopus sp. 20 (Norman, 2000) drawn from a photograph by Denise Tackett. (K-M) A. aculeatus (North Sulawesi) drawn from frames of a video and field drawings.

View larger version (116K): [in a new window]   Fig. 2. Locomotion by Abdopus aculeatus (Lizard Island, Australia). (A) Jetting (see also Movie 1 in supplementary material for `medusoid' jetting, which incorporates the arms); (B) swimming; (C) crawling; (D) walking (see Movies 2 and 3 in supplementary material).

View larger version (11K): [in a new window]   Fig. 3. Relationship between mantle length (mm) and mass (g) of adult Abdopus aculeatus, with the trendline mass=2.42ML-46.61; R2=0.95.

View larger version (154K): [in a new window]   Fig. 4. Variety of body positions of A. aculeatus during locomotion. (A) Walking backward, arms coiled close to the body; (B) walking obliquely backward; (C) walking forward, arms raised; (D) conical crawling (any direction), mantle conical, arms tucked under or pulled close to the body; (E) curled arm jetting; (F) walking, arms tucked under the body; (G) crawling forward upright; (H) female (right) crawling dragging mating male (left); (I) crawling (any direction), mantle upright, arms tightly coiled; (J) hopping, arm tips coiled tightly; (K) Individual O-11 hopping on the hectocotylus. Note small regenerating arms, including arm pair IV.

View larger version (14K): [in a new window]   Fig. 5. (A) Swimming speed of A. aculeatus using the head raised (HR, black) vs flat, dorsoventrally compressed (DVC, gray) body forms. DVC swimming was consistently faster per individual than HR swimming (paired t-test P=0.004). (B) Relative speed of modes. Mean speeds of A. aculeatus during modes of locomotion measured in BL s-1 (Freidman test statistic 16.00; P=0.003). Horizontal lines are drawn over groups that are not significantly different from each other, as determined by pairwise Wilcoxon signed rank tests adjusted for multiple comparisons (e=0.005). Maximum speeds are given above these lines. Bars indicate standard error (s.e.m.), N=10 (jet), 9 (swim), 5 (walk), 5 (multi-armed walk), 10 (crawl). (C) Absolute speed of modes. Mean speeds of A. aculeatus during modes of locomotion measured in cm s-1 (Freidman test statistic 11.80; P=0.019). Horizontal lines are drawn over groups that are not significantly different from each other, as determined by pairwise Wilcoxon signed rank tests adjusted for multiple comparisons (e=0.005). Maximum speeds are given above these lines. Bars indicate s.e.m., N=8 (jet), 9 (swim), 5 (walk), 5 (multi-armed walk), 10 (crawl).