Locomotion of Worms

Yapp, W. B.; Roots, Betty I.

doi:10.1038/177614a0

Cited by 16 publications

(7 citation statements)

References 4 publications

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“…Because the peristaltic wave often dissipates as it travels down the length of the body, segments closer to the tail are likely of less importance in burrowing than those near the head (Yapp and Roots, 1956). Our data are consistent with this proposal as longitudinal force production of the anterior segments increased at a greater rate (F l α M 0.724 ) than expected from isometry, while the middle and posterior segments scaled close to isometry.…”

Section: Intersegmental Differencessupporting

confidence: 81%

Scaling of the hydrostatic skeleton in the earthwormLumbricus terrestris

Kurth

Kier

2014

Journal of Experimental Biology

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The structural and functional consequences of changes in size or scale have been well studied in animals with rigid skeletons, but relatively little is known about scale effects in animals with hydrostatic skeletons. We used glycol methacrylate histology and microscopy to examine the scaling of mechanically important morphological features of the earthworm Lumbricus terrestris over an ontogenetic size range from 0.03 to 12.89 g. We found that L. terrestris becomes disproportionately longer and thinner as it grows. This increase in the length to diameter ratio with size means that, when normalized for mass, adult worms gain ~117% mechanical advantage during radial expansion, compared with hatchling worms. We also found that the cross-sectional area of the longitudinal musculature scales as body mass to the ~0.6 power across segments, which is significantly lower than the 0.66 power predicted by isometry. The cross-sectional area of the circular musculature, however, scales as body mass to thẽ 0.8 power across segments, which is significantly higher than predicted by isometry. By modeling the interaction of muscle crosssectional area and mechanical advantage, we calculate that the force output generated during both circular and longitudinal muscle contraction scales near isometry. We hypothesize that the allometric scaling of earthworms may reflect changes in soil properties and burrowing mechanics with size. KEY WORDS: Scaling, Allometry, Ontogeny, Annelid, Burrowing INTRODUCTIONBody size plays a pivotal role in the structure and function of all organisms. Size affects how an organism interacts with its environment as well as the processes needed for survival (Vogel, 1988). Size also imposes physical constraints on organisms, with fundamental effects on organismal design (Schmidt-Nielsen, 1997). A range of important traits change as a function of body size, including: geometry, metabolic rate, kinematics, mechanics and even lifespan. As a consequence, almost every facet of an organism's life may be influenced by its size, including its physiology, morphology, ecology and biomechanics (Schmidt-Nielsen, 1984;Quillin, 1999;Vogel, 2013;Biewener, 2005;Hill et al., 2012). Scaling, the changes in form and function due body size, has been studied primarily in the vertebrates and in some arthropods (e.g. Schmidt-Nielsen, 1997;Biewener, 2005;Nudds, 2007;Chi and Roth, 2010). The effects of scaling on soft-bodied animals have, however, received relatively little attention. The aim of this study was to use histological and microscopic techniques to examine the effects of size and scale on components of the hydrostatic skeleton of an iconic soft-bodied animal, the earthworm.

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Section: Intersegmental Differencessupporting

confidence: 81%

Scaling of the hydrostatic skeleton in the earthwormLumbricus terrestris

Kurth

Kier

2014

Journal of Experimental Biology

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“…Earthworms crawling by peristalsis slip on smooth surfaces such as glass [32]. Gastropods slip less with their muscular foot because of adhesion from mucus, and they, as well as crawlers such as leeches and caterpillars that grasp or adhere to surfaces, are able to move on inclined surfaces much more effectively.…”

Section: Crawling On a Surfacementioning

confidence: 99%

“…Even more extreme are leeches, which use two-anchor crawling and adhere with one end using suckers while moving the rest of the body forward either with the body close to the substratum in vermiform crawling or by taking long strides with the body raised higher above the substratum in inch-worm crawling [37]. Earthworms can use their peristomium to create suction and adhere to smooth surfaces to reduce slipping [32], but whether this behavior occurs in the natural environment and its importance to locomotion are unclear.…”

Section: Crawling On a Surfacementioning

confidence: 99%

“…Contraction of circular muscles in the advancing segments of crawling earthworms decreases the diameter of moving segments [31], which likely results in a greater proportion of body mass being supported by the stationary segments. The moving segments are also often raised off of smooth surfaces [32], reducing kinetic friction. Gastropods may also reduce forward friction by focusing the body weight on the stationary parts of the foot.…”

Section: Crawling On a Surfacementioning

confidence: 99%

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Environmental Constraints on the Mechanics of Crawling and Burrowing Using Hydrostatic Skeletons

Dorgan

2010

Exp Mech

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Mechanics, kinematics, and energetics of crawling and burrowing by limbless organisms using hydrostatic skeletons depend on the medium and mode in which the organism is moving. Whether the animal is moving over or through a solid has long been considered important enough to distinguish crawling and burrowing as different terms, and in fact the mechanics are very different. Crawlers use mechanisms to increase friction to generate thrust while reducing resistive friction. Burrowers in elastic muds extend their burrows by fracture, whereas sands are fluidized by burrowers much larger than grain sizes and smaller burrowers displace individual grains. Gravitational forces depend on how closely the density of the organism matches that of its fluid surroundings, therefore frictional forces depend on whether the organism is moving through air or water and fluidization on whether sands are saturated or unsaturated.

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“…The worm was then killed and three blocks of tissue containing 20 segments each were removed (segments 1-20, 21-40 and 41-60, numbering from anterior) to account for morphological differences across segments. We focused on segments in the anterior half of the worm since it is of greatest importance in locomotion (Yapp, 1956).…”

Section: Histology and Morphometricsmentioning

confidence: 99%

Differences in scaling and morphology between lumbricid earthworm ecotypes

Kurth¹,

Kier

2015

Journal of Experimental Biology

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Many soft-bodied invertebrates use a flexible, fluid-filled hydrostatic skeleton for burrowing. The aim of our study was to compare the scaling and morphology between surface-dwelling and burrowing earthworm ecotypes to explore the specializations of non-rigid musculoskeletal systems for burrowing locomotion. We compared the scaling of adult lumbricid earthworms across species and ecotypes to determine whether linear dimensions were significantly associated with ecotype. We also compared the ontogenetic scaling of a burrowing species, Lumbricus terrestris, and a surface-dwelling species, Eisenia fetida, using glycol methacrylate histology. We show that burrowing species are longer, thinner and have higher length-todiameter ratios than non-burrowers, and that L. terrestris is thinner for any given body mass compared with E. fetida. We also found differences in the size of the musculature between the two species that may correlate with surface crawling or burrowing. Our results suggest that adaptations to burrowing for soft-bodied animals include a disproportionately thin body and strong longitudinal muscles.

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Locomotion of Worms

Cited by 16 publications

References 4 publications

Scaling of the hydrostatic skeleton in the earthwormLumbricus terrestris

Scaling of the hydrostatic skeleton in the earthwormLumbricus terrestris

Environmental Constraints on the Mechanics of Crawling and Burrowing Using Hydrostatic Skeletons

Differences in scaling and morphology between lumbricid earthworm ecotypes

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