Elastic energy storage in the hopping of kangaroo rats (Dipodomys spectabilis)

It is widely believed that elastic energy storage is more important in the locomotion of larger mammals. This is based on: (a) comparison of kangaroos with the smaller kangaroo rat; and (b) calculations that predict that the capacity for elastic energy storage relative to body mass increases with size. Here we argue that: (i) data from kangaroos and kangaroo rats cannot be generalized to other mammals; (ii) the elastic energy storage capacity relative to body mass is not indicative of the importance of elastic energy to an animal; and (iii) the contribution of elastic energy to the mechanical work of locomotion will not increase as rapidly with size as the mass-specific energy storage capacity, because larger mammals must do relatively more mechanical work per stride. We predict how the ratio of elastic energy storage to mechanical work will change with size in quadrupedal mammals by combining empirical scaling relationships from the literature. The results suggest that the percentage contribution of elastic energy to the mechanical work of locomotion decreases with size, so that elastic energy is more important in the locomotion of smaller mammals. This now needs to be tested experimentally.

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Elastic energy storage across speeds during steady-state hopping of desert kangaroo rats (Dipodomys deserti)

Journal of Experimental Biology ◽

10.1242/jeb.242954 ◽

2022 ◽

Author(s):

Brooke A. Christensen ◽

David C. Lin ◽

M. Janneke Schwaner ◽

Craig P. McGowan

Keyword(s):

Energy Storage ◽

Elastic Energy ◽

Kangaroo Rats ◽

Storage Mechanism ◽

Extensor Tendons ◽

Tendon Thickness ◽

Recent Species ◽

Specific Material ◽

Species Specific

Small bipedal hoppers, including kangaroo rats, are thought to not benefit from substantial elastic energy storage and return during hopping. However, recent species-specific material properties research suggests that, despite relative thickness, the ankle extensor tendons of these small hoppers are considerably more compliant than had been assumed. With faster locomotor speeds demanding higher forces, a lower tendon stiffness suggests greater tendon deformation and thus a greater potential for elastic energy storage and return with increasing speed. Using the elastic modulus values specific to kangaroo rat tendons, we sought to determine how much elastic energy is stored and returned during hopping across a range of speeds. In vivo techniques were used to record tendon force in the ankle extensors during steady-speed hopping. Our data support the hypothesis that the ankle extensor tendons of kangaroo rats store and return elastic energy in relation to hopping speed, storing more at faster speeds. Despite storing comparatively less elastic energy than larger hoppers, this relationship between speed and energy storage offer novel evidence of a functionally similar energy storage mechanism, operating irrespective of body size or tendon thickness, across the distal muscle-tendon units of both small and large bipedal hoppers.

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Jumping, Climbing and Suspensory Locomotion

10.1093/oso/9780198743156.003.0007 ◽

2018 ◽

Keyword(s):

Energy Storage ◽

Elastic Energy ◽

The Core ◽

Power Amplification ◽

Core Concepts

Jumping, climbing and suspensory locomotion are specialized locomotor mechanisms used on land and in the air. Jumping is used for rapid launches from substrates. Climbing and suspensory movements enable locomotion up, under and through vertically-structured habitats, such as forests. Elastic energy storage is particularly important for jumping and catapult systems and we address the core concepts of power amplification that are exemplified in nature’s extreme jumpers. We examine the diverse mechanisms of attachment that characterize animals that can grasp and adhere to a diversity of structures. We conclude the chapter by examining the integration of biological capabilities with engineering innovations in these systems.

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Evidence for a vertebrate catapult: elastic energy storage in the plantaris tendon during frog jumping

Biology Letters ◽

10.1098/rsbl.2011.0982 ◽

2011 ◽

Vol 8 (3) ◽

pp. 386-389 ◽

Cited By ~ 85

Author(s):

Henry C. Astley ◽

Thomas J. Roberts

Keyword(s):

Energy Storage ◽

Elastic Energy ◽

High Speed ◽

Angular Acceleration ◽

Whole Body ◽

Joint Motion ◽

Joint Movement ◽

Fascicle Length ◽

Muscle Fascicle ◽

Muscle Shortening

Anuran jumping is one of the most powerful accelerations in vertebrate locomotion. Several species are hypothesized to use a catapult-like mechanism to store and rapidly release elastic energy, producing power outputs far beyond the capability of muscle. Most evidence for this mechanism comes from measurements of whole-body power output; the decoupling of joint motion and muscle shortening expected in a catapult-like mechanism has not been demonstrated. We used high-speed marker-based biplanar X-ray cinefluoroscopy to quantify plantaris muscle fascicle strain and ankle joint motion in frogs in order to test for two hallmarks of a catapult mechanism: (i) shortening of fascicles prior to joint movement (during tendon stretch), and (ii) rapid joint movement during the jump without rapid muscle-shortening (during tendon recoil). During all jumps, muscle fascicles shortened by an average of 7.8 per cent (54% of total strain) prior to joint movement, stretching the tendon. The subsequent period of initial joint movement and high joint angular acceleration occurred with minimal muscle fascicle length change, consistent with the recoil of the elastic tendon. These data support the plantaris longus tendon as a site of elastic energy storage during frog jumping, and demonstrate that catapult mechanisms may be employed even in sub-maximal jumps.

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Microsatellite analyses across three diverse vertebrate transcriptomes (Acipenser fulvescens, Ambystoma tigrinum, and Dipodomys spectabilis)

Genome ◽

10.1139/gen-2013-0056 ◽

2013 ◽

Vol 56 (7) ◽

pp. 407-414 ◽

Cited By ~ 8

Author(s):

Jacqueline M. Doyle ◽

Gregor Siegmund ◽

Joseph D. Ruhl ◽

Soo Hyung Eo ◽

Matthew C. Hale ◽

...

Keyword(s):

Lake Sturgeon ◽

Untranslated Regions ◽

Ambystoma Tigrinum ◽

Acipenser Fulvescens ◽

Data Sets ◽

Noncoding Dna ◽

Kangaroo Rats ◽

Tiger Salamanders ◽

Dipodomys Spectabilis ◽

In Silico Polymorphism

Historically, many population genetics studies have utilized microsatellite markers sampled at random from the genome and presumed to be selectively neutral. Recent studies, however, have shown that microsatellites can occur in transcribed regions, where they are more likely to be under selection. In this study, we mined microsatellites from transcriptomes generated by 454-pyrosequencing for three vertebrate species: lake sturgeon (Acipenser fulvescens), tiger salamander (Ambystoma tigrinum), and kangaroo rat (Dipodomys spectabilis). We evaluated (i) the occurrence of microsatellites across species; (ii) whether particular gene ontology terms were over-represented in genes that contained microsatellites; (iii) whether repeat motifs were located in untranslated regions or coding sequences of genes; and (iv) in silico polymorphism. Microsatellites were less common in tiger salamanders than in either lake sturgeon or kangaroo rats. Across libraries, trinucleotides were found more frequently than any other motif type, presumably because they do not cause frameshift mutations. By evaluating variation across reads assembled to a given contig, we were able to identify repeat motifs likely to be polymorphic. Our study represents one of the first comparative data sets on the distribution of vertebrate microsatellites within expressed genes. Our results reinforce the idea that microsatellites do not always occur in noncoding DNA, but commonly occur in expressed genes.

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