Types of locomotion in ophiurans

Arshavskii, Yu. I.; Kashin, S. M.; Литвинова, Н. М.; Orlovskii, G. N.; Feldman, Anatol G.

doi:10.1007/bf01063602

Cited by 20 publications

(46 citation statements)

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“…Given its infrequency in this study, this may represent a genuine preference for rowing, though further work is needed to confirm this. A previously described 'pulling' mode (Arshavskii et al, 1976b) was not observed, nor was there any evidence of the use of tube feet in locomotion (Arshavskii et al, 1976b). This may be due to errors in prior qualitative assessments or differences in substrate, as in prior studies the brittle stars moved across bare glass of an aquarium rather than natural sand (Arshavskii et al, 1976b).…”

Section: Discussionmentioning

confidence: 84%

“…Two locomotor modes were observed during locomotion of this species, both of which corresponded to previous descriptions. Rowing was previously described in qualitative terms by several authors (Arshavskii et al, 1976b;Glaser, 1907;Maier and Schneirla, 1935;Romanes, 1885), and is the most clearly obvious from visual examination. Reverse rowing was also described previously in the literature (Glaser, 1907;von Uexkull, 1905), though not nearly as commonly.…”

Section: Discussionmentioning

confidence: 99%

“…A previously described 'pulling' mode (Arshavskii et al, 1976b) was not observed, nor was there any evidence of the use of tube feet in locomotion (Arshavskii et al, 1976b). This may be due to errors in prior qualitative assessments or differences in substrate, as in prior studies the brittle stars moved across bare glass of an aquarium rather than natural sand (Arshavskii et al, 1976b). The 'pulling' mode was distinguished solely by movement of the central limb and its hypothesized role in force generation (Arshavskii et al, 1976b), but given the highly variable movement of this appendage and the uncertainty in determining force production from kinematics (see below), this distinction cannot be confirmed without direct force measurements.…”

Section: Discussionmentioning

confidence: 99%

“…Rowing, previously described qualitatively (Arshavskii et al, 1976b;Glaser, 1907;Maier and Schneirla, 1935;Romanes, 1885), was characterized by a forward-directed center limb and large angular movements of the right and left forelimbs during swing and stance phases compared with other limbs (Table2, Fig.2A,B, Fig.4A-C, supplementary material Movie1). Changes in limb length were small for all limbs (Table2, Fig.4A-C).…”

Section: Brittlementioning

confidence: 99%

“…Brittle stars can detect and respond to light as well as to tactile and chemical stimuli (Cowles, 1910;Sloan and Campbell, 1982). Several prior studies qualitatively described the locomotion of brittle stars, often noting the apparent bilateral symmetry and coordination of their locomotion and likening it to tetrapod gaits (Arshavskii et al, 1976a;Arshavskii et al, 1976b;Glaser, 1907;Maier and Schneirla, 1935;Romanes, 1885). However, while qualitative assessment can give insight into locomotion, the high variability in limb movements and the need to simultaneously track multiple identical limbs limits the usefulness of such methods.…”

Section: Introductionmentioning

confidence: 99%

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Getting around when you’re round: quantitative analysis of the locomotion of the blunt-spined brittle star,Ophiocoma echinata

Astley

2012

Journal of Experimental Biology

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SUMMARYBrittle stars (Ophiuroidea, Echinodermata) are pentaradially symmetrical echinoderms that use five multi-jointed limbs to locomote along the seafloor. Prior qualitative descriptions have claimed coordinated movements of the limbs in a manner similar to tetrapod vertebrates, but this has not been evaluated quantitatively. It is uncertain whether the ring-shaped nervous system, which lacks an anatomically defined anterior, is capable of generating rhythmic coordinated movements of multiple limbs. This study tested whether brittle stars possess distinct locomotor modes with strong inter-limb coordination as seen in limbed animals in other phyla (e.g. tetrapods and arthropods), or instead move each limb independently according to local sensory feedback. Limb tips and the body disk were digitized for 56 cycles from 13 individuals moving across sand. Despite their pentaradial anatomy, all individuals were functionally bilateral, moving along the axis of a central limb via synchronous motions of contralateral limbs (±~13% phase lag). Two locomotor modes were observed, distinguishable mainly by whether the central limb was directed forwards or backwards. Turning was accomplished without rotation of the body disk by defining a different limb as the center limb and shifting other limb identities correspondingly, and then continuing locomotion in the direction of the newly defined anterior. These observations support the hypothesis that, in spite of their radial body plan, brittle stars employ coordinated, bilaterally symmetrical locomotion. Supplementary material available online at

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Section: Discussionmentioning

confidence: 84%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Brittlementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Getting around when you’re round: quantitative analysis of the locomotion of the blunt-spined brittle star,Ophiocoma echinata

Astley

2012

Journal of Experimental Biology

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Autonomous Decentralized Control Mechanism in Resilient Ophiuroid Locomotion

Kano

Ishiguro

2012

Lecture Notes in Computer Science

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Arm Coordination in Octopus Crawling Involves Unique Motor Control Strategies

2015

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To cope with the exceptional computational complexity that is involved in the control of its hyper-redundant arms [1], the octopus has adopted unique motor control strategies in which the central brain activates rather autonomous motor programs in the elaborated peripheral nervous system of the arms [2, 3]. How octopuses coordinate their eight long and flexible arms in locomotion is still unknown. Here, we present the first detailed kinematic analysis of octopus arm coordination in crawling. The results are surprising in several respects: (1) despite its bilaterally symmetrical body, the octopus can crawl in any direction relative to its body orientation; (2) body and crawling orientation are monotonically and independently controlled; and (3) contrasting known animal locomotion, octopus crawling lacks any apparent rhythmical patterns in limb coordination, suggesting a unique non-rhythmical output of the octopus central controller. We show that this uncommon maneuverability is derived from the radial symmetry of the arms around the body and the simple pushing-by-elongation mechanism by which the arms create the crawling thrust. These two together enable a mechanism whereby the central controller chooses in a moment-to-moment fashion which arms to recruit for pushing the body in an instantaneous direction. Our findings suggest that the soft molluscan body has affected in an embodied way [4, 5] the emergence of the adaptive motor behavior of the octopus.

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Types of locomotion in ophiurans

Cited by 20 publications

References 0 publications

Getting around when you’re round: quantitative analysis of the locomotion of the blunt-spined brittle star,Ophiocoma echinata

Getting around when you’re round: quantitative analysis of the locomotion of the blunt-spined brittle star,Ophiocoma echinata

Autonomous Decentralized Control Mechanism in Resilient Ophiuroid Locomotion

Arm Coordination in Octopus Crawling Involves Unique Motor Control Strategies

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