The metabolic cost of turning right side up in the Mediterranean spur-thighed tortoise (Testudo graeca)

Ewart, Heather; Tickle, Peter G.; Sellers, William I.; Lambertz, Markus; Crossley, Dane A.; Codd, Jonathan R.

doi:10.1038/s41598-021-04273-w

Cited by 4 publications

(4 citation statements)

References 49 publications

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“…During each trial, oxygen consumption and carbon dioxide production were measured using respirometry. A subset of these data for tortoises moving at a single speed were previously reported for comparison with the metabolic cost of self-righting [ 12 ]. These experiments were approved by the University of Manchester Animals Ethics Committee (Permit D.039) in accordance with the Animal (Scientific Procedures) Act 1986.…”

Section: Methodsmentioning

confidence: 99%

“…These adaptations for efficiency in terrestrial locomotion in tortoises, however, do appear to come with a trade-off should their behaviour and movement require rapid limb movements. For example, the relatively high metabolic cost of self-righting, which is up to five-fold higher than that during walking, is thought to be linked in part to the associated rapid movements of the limbs during this behaviour [ 12 ]. A slow rate of muscle contraction may therefore be adaptive for walking but not other behaviours [ 12 ].…”

Section: Introductionmentioning

confidence: 99%

“…For example, the relatively high metabolic cost of self-righting, which is up to five-fold higher than that during walking, is thought to be linked in part to the associated rapid movements of the limbs during this behaviour [ 12 ]. A slow rate of muscle contraction may therefore be adaptive for walking but not other behaviours [ 12 ].…”

Section: Introductionmentioning

confidence: 99%

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Mediterranean Spur-Thighed Tortoises (Testudo graeca) Have Optimal Speeds at Which They Can Minimise the Metabolic Cost of Transport, on a Treadmill

Ewart

Tickle

Nudds

et al. 2022

Biology

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Tortoises are famed for their slow locomotion, which is in part related to their herbivorous diet and the constraints imposed by their protective shells. For most animals, the metabolic cost of transport (CoT) is close to the value predicted for their body mass. Testudines appear to be an exception to this rule, as previous studies indicate that, for their body mass, they are economical walkers. The metabolic efficiency of their terrestrial locomotion is explainable by their walking gait biomechanics and the specialisation of their limb muscle physiology, which embodies a predominance of energy-efficient slow-twitch type I muscle fibres. However, there are only two published experimental reports of the energetics of locomotion in tortoises, and these data show high variability. Here, Mediterranean spur-thighed tortoises (Testudo graeca) were trained to walk on a treadmill. Open-flow respirometry and high-speed filming were simultaneously used to measure the metabolic cost of transport and to quantify limb kinematics, respectively. Our data support the low cost of transport previously reported and demonstrate a novel curvilinear relationship to speed in Testudines, suggesting tortoises have an energetically optimal speed range over which they can move in order to minimise the metabolic cost of transport.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Mediterranean Spur-Thighed Tortoises (Testudo graeca) Have Optimal Speeds at Which They Can Minimise the Metabolic Cost of Transport, on a Treadmill

Ewart

Tickle

Nudds

et al. 2022

Biology

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“…Testudines with highly domed carapaces, generally self-right by rotating the limbs to generate momentum, shifting the centre of mass, and initiating a shell roll. A strategy seen in terrestrial species like the star ( Geochelone ) , leopard ( Stigmochelys ) and Madagascan ( Astrochelys ) tortoises and in some semi-aquatic species like the North American box turtles ( Terrapene ) 1 , 2 , 7 , 8 , 11 . Alternatively, species with flatter and often more streamlined carapaces employ a different tactic.…”

Section: Introductionmentioning

confidence: 99%

Shell shape does not accurately predict self-righting ability in hatchling freshwater turtles

van Casteren,

Sellers,

Crossley

et al. 2024

Sci Rep

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Flat hydrodynamic shells likely represent an evolutionary trade-off between adaptation to an aquatic lifestyle and the instability of more rounded shells, thought beneficial for self-righting. Trade-offs often result in compromises, this is particularly true when freshwater turtles, with flatter shells, must self-right to avoid the negative effects of inverting. These turtles, theoretically, invest more biomechanical effort to achieve successful and timely self-righting when compared to turtles with rounded carapaces. This increase in effort places these hatchlings in a precarious position; prone to inversion and predation and with shells seemingly maladapted to the act of self-righting. Here, we examine hatchling self-righting performance in three morphologically distinct freshwater turtle species (Apalone spinifera, Chelydra serpentina and Trachemys scripta scripta) that inhabit similar environmental niches. We demonstrate that these hatchlings were capable of rapid self-righting and used considerably less biomechanical effort relative to adult turtles. Despite differences in shell morphology the energetic efficiency of self-righting remained remarkably low and uniform between the three species. Our results confound theoretical predictions of self-righting ability based on shell shape metrics and indicate that other morphological characteristics like neck or tail morphology and shell material properties must be considered to better understand the biomechanical nuances of Testudine self-righting.

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Recent Progress in the Physical Principles of Dynamic Ground Self-Righting

2024

Integrative and Comparative Biology

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Animals and robots must self-right on the ground after overturning. Biology research described various strategies and motor patterns in many species. Robotics research devised many strategies. However, we do not well understand how the physical principles of how the need to generate mechanical energy to overcome the potential energy barrier governs behavioral strategies and 3-D body rotations given the morphology. Here I review progress on this which I led studying cockroaches self-righting on level, flat, solid, low-friction ground, by integrating biology experiments, robotic modeling, and physics modeling. Animal experiments using three species (Madagascar hissing, American, and discoid cockroaches) found that ground self-righting is strenuous and often requires multiple attempts to succeed. Two species (American and discoid cockroaches) often self-right dynamically, using kinetic energy to overcome the barrier. All three species use and often stochastically transition across diverse strategies. In these strategies, propelling motions are often accompanied by perturbing motions. All three species often display complex yet stereotyped body rotation. They all roll more in successful attempts than in failed ones, which lowers the barrier, as revealed by a simplistic 3-D potential energy landscape of a rigid body self-righting. Experiments of an initial robot self-righting via rotation about a fixed axis revealed that, the longer and faster appendages push, the more mechanical energy can be gained to overcome the barrier. However, the cockroaches rarely achieve this. To further understand the physical principles of strenuous ground self-righting, we focused on the discoid cockroach's leg-assisted winged self-righting. In this strategy, wings propel against the ground to pitch the body up but are unable to overcome the highest pitch barrier. Meanwhile, legs flail in the air to perturb the body sideways to self-right via rolling. Experiments using a refined robot and an evolving 3-D potential energy landscape revealed that, although wing propelling cannot generate sufficient kinetic energy to overcome the highest pitch barrier, it reduces the barrier to allow small kinetic energy from the perturbing legs to probabilistically overcome the barrier to self-right via rolling. Thus, only by combining propelling and perturbing can self-righting be achieved, when it is so strenuous; this physical constraint leads to the stereotyped body rotation. Finally, multi-body dynamics simulation and template modeling revealed that the animal's substantial randomness in wing and leg motions help it by chance to find good coordination, which accumulates more mechanical energy to overcome the barrier, thus increasing the likelihood of self-righting.

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The metabolic cost of turning right side up in the Mediterranean spur-thighed tortoise (Testudo graeca)

Cited by 4 publications

References 49 publications

Mediterranean Spur-Thighed Tortoises (Testudo graeca) Have Optimal Speeds at Which They Can Minimise the Metabolic Cost of Transport, on a Treadmill

Mediterranean Spur-Thighed Tortoises (Testudo graeca) Have Optimal Speeds at Which They Can Minimise the Metabolic Cost of Transport, on a Treadmill

Shell shape does not accurately predict self-righting ability in hatchling freshwater turtles

Recent Progress in the Physical Principles of Dynamic Ground Self-Righting

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