Why arboreal snakes should not be cylindrical: body shape, incline and surface roughness have interactive effects on locomotion

Jayne, Bruce C.; Newman, Steven; Zentkovich, Michele M.; Berns, H. Matthew

doi:10.1242/jeb.129379

Cited by 23 publications

(34 citation statements)

References 42 publications

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“…We studied brown tree snakes, Boiga irregularis (Merrem 1802), for several reasons. Firstly, the gap-bridging performance, arboreal locomotion and axial anatomy of this species are well known (Byrnes and Jayne, 2012;Hoefer and Jayne, 2013;Jayne et al, 2015;Jayne and Riley, 2007). Secondly, brown tree snakes are relatively slender for a given length (Hoefer and Jayne, 2013;Jayne and Riley, 2007) and the tendons of the SSP are very long ( Fig.…”

Section: Materials and Methods Experimental Subjectsmentioning

confidence: 99%

Three-dimensional trajectories affect the epaxial muscle activity of arboreal snakes crossing gaps

Jorgensen

Jayne

2017

Journal of Experimental Biology

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The need for long-axis support is widespread among non-aquatic vertebrates and may be particularly acute for arboreal snakes when many vertebrae span sizable gaps between branches with diverse orientations. Hence, we used brown tree snakes () bridging gaps to test how three-dimensional trajectories affected muscle activity and whether these motor patterns differed from those for the locomotion of terrestrial snakes and movements of other vertebrates. We used five trajectories: pitch angles of 90, 0 and -90 deg (downward) when yaw=0 deg, and 90 deg yaw angles to the left and right when pitch=0 deg. We recorded movement and electromyograms from the three largest epaxial muscles, which from dorsal to ventral are the semispinalis-spinalis (SSP), longissimus dorsi (LD) and iliocostalis (IL). Overall, the SSP had extensive bilateral activity, which resembled the motor pattern during the dorsiflexion of sidewinding snakes. Unlike any previously described terrestrial snake locomotion, bilateral activity of the LD and IL was also common during gap bridging. The largest amounts of muscle activity usually occurred for horizontal gaps, and muscle activity decreased markedly as soon as the snake's head touched the far edge of the gap. Snakes had the least amount of muscle activity for pitch=-90 deg. While turning sideways, muscles on the convex side had less activity when turning compared with the concave side. Hence, the orientation relative to gravity profoundly affected muscle activity during gap bridging, and these complex three-dimensional movements involved several previously undescribed variants of axial motor pattern.

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Section: Materials and Methods Experimental Subjectsmentioning

confidence: 99%

Three-dimensional trajectories affect the epaxial muscle activity of arboreal snakes crossing gaps

Jorgensen

Jayne

2017

Journal of Experimental Biology

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“…Relation between the location of the anchor point and the fraction coefficients. References (34)(35)(36)(37)(38)…”

Section: Supplementary Materialsmentioning

confidence: 99%

Kirigami skins make a simple soft actuator crawl

et al. 2018

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Bioinspired soft machines made of highly deformable materials are enabling a variety of innovative applications, yet their locomotion typically requires several actuators that are independently activated. We harnessed kirigami principles to significantly enhance the crawling capability of a soft actuator. We designed highly stretchable kirigami surfaces in which mechanical instabilities induce a transformation from flat sheets to 3D-textured surfaces akin to the scaled skin of snakes. First, we showed that this transformation was accompanied by a dramatic change in the frictional properties of the surfaces. Then, we demonstrated that, when wrapped around an extending soft actuator, the buckling-induced directional frictional properties of these surfaces enabled the system to efficiently crawl.

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“…Furthermore, some species of snakes can perform lateral undulation on smooth solid surfaces lacking any macroscopic projections that are large enough to contact the sides of the snake ( Hu et al. 2009 ; Jayne et al. 2015 ).…”

Section: Lateral Undulationmentioning

confidence: 99%

“…2009 ), but some arboreal species can also make a keel ( Fig. 4A ) that may reduce slipping on surfaces that superficially seem smooth and ill-suited for lateral undulation ( Jayne et al. 2015 ).…”

Section: Lateral Undulationmentioning

confidence: 99%

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What Defines Different Modes of Snake Locomotion?

Jayne

2020

Integrative and Comparative Biology

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Synopsis Animals move in diverse ways, as indicated in part by the wide variety of gaits and modes that have been described for vertebrate locomotion. Much variation in the gaits of limbed animals is associated with changing speed, whereas different modes of snake locomotion are often associated with moving on different surfaces. For several decades different types of snake locomotion have been categorized as one of four major modes: rectilinear, lateral undulation, sidewinding, and concertina. Recent empirical work shows that the scheme of four modes of snake locomotion is overly conservative. For example, during aquatic lateral undulation, the timing between muscle activity and lateral bending changes along the length of the snake, which is unlike terrestrial lateral undulation. The motor pattern used to prevent sagging while bridging gaps also suggests that arboreal lateral undulation on narrow surfaces or with a few discrete points of support has a different motor pattern than terrestrial lateral undulation when the entire length of the snake is supported. In all types of concertina locomotion, the distance from the head to the tail changes substantially as snakes alternately flex and then extend different portions of their body. However, snakes climbing cylinders with concertina exert forces medially to attain a purchase on the branch, whereas tunnels require pushing laterally to form an anchoring region. Furthermore, different motor patterns are used for these two types of concertina movement. Some snakes climb vertical cylinders with helical wrapping completely around the cylinder, whereas all other forms of concertina bend regions of the body alternately to the left and right. Current data support rectilinear locomotion and sidewinding as being distinct modes, whereas lateral undulation and concertina are best used for defining categories of gaits with some unifying similarities. Partly as a result of different motor patterns, I propose recognizing five and four distinct types of lateral undulation and concertina, respectively, resulting in a total of 11 distinct gaits previously recognized as only four.

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Why arboreal snakes should not be cylindrical: body shape, incline and surface roughness have interactive effects on locomotion

Cited by 23 publications

References 42 publications

Three-dimensional trajectories affect the epaxial muscle activity of arboreal snakes crossing gaps

Three-dimensional trajectories affect the epaxial muscle activity of arboreal snakes crossing gaps

Kirigami skins make a simple soft actuator crawl

What Defines Different Modes of Snake Locomotion?

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