Energetics and mechanics of terrestrial locomotion. III. Energy changes of the centre of mass as a function of speed and body size in birds and mammals

1982 ◽  
Vol 97 (1) ◽  
pp. 41-56 ◽  
Author(s):  
N. C. Heglund ◽  
G. A. Cavagna ◽  
C. R. Taylor
Keyword(s):  
Body Size ◽  
Total Power ◽  
Small Animals ◽  
Similar Data ◽  
Centre Of Mass ◽  
Average Speed ◽  
Terrestrial Locomotion ◽  
The Third ◽  
Large Animals ◽  
Level Constant

This is the third in a series of four papers examining the link between the energetics and mechanics of terrestrial locomotion. It reports measurements of the mechanical work required (ECM, tot) to lift and reaccelerate an animal's centre of mass within each step as a function of speed and body size during level, constant average speed locomotion. A force platform was used in this study to measure ECM, tot for small bipeds, quadrupeds and hoppers. We have already published similar data from large animals. The total power required to lift and reaccelerate the centre of mass (ECM, tot) increased nearly linearly with speed for all the animals. Expressed in mass-specific terms, it was independent of body size and could be expressed by a simple equation: ECM, tot/Mb = 0.685 vg + 0.072 where ECM, tot/Mb has the units of W kg-1 and vg is speed in m s-1. Walking involves the same pendulum-like mechanism in small animals as has been described in humans and large animals. Also, running, trotting and hopping produce similar curves of ECM, tot as a function of time during a stride for both the small and large animals. Galloping, however, appears to be different in small and large animals. In small animals the front legs are used mainly for braking, while the back legs are used to reaccelerate the centre of mass within a stride. In large animals the front and hind legs serve to both brake and reaccelerate the animal; this difference in mechanics is significant in that it does not allow the utilization of elastic energy in the legs of small animals, but does in the legs of large animals.

Energetics and mechanics of terrestrial locomotion. IV. Total mechanical energy changes as a function of speed and body size in birds and mammals

1982 ◽  
Vol 97 (1) ◽  
pp. 57-66 ◽  
Author(s):  
N. C. Heglund ◽  
M. A. Fedak ◽  
C. R. Taylor ◽  
G. A. Cavagna
Keyword(s):  
Body Size ◽  
Kinetic Energy ◽  
Elastic Energy ◽  
Mechanical Energy ◽  
Motor Units ◽  
Metabolic Energy ◽  
Small Animals ◽  
Centre Of Mass ◽  
Terrestrial Locomotion ◽  
Total Mechanical Energy

This is the final paper in or series examining the link between the energetics and mechanics of terrestrial locomotion. In this paper the kinetic energy of the limbs and body relative to the centre of mass (EKE, tot of paper two) is combined with the potential plus kinetic energy of the centre of mass (ECM, tot of paper three) to obtain the total mechanical energy (excluding elastic energy) of an animal during constant average-speed locomotion. The minimum mass-specific power required of the muscles and tendons to maintain the observed oscillations in total energy, Etot/Mb, can be described by one equation: Etot/Mb = 0.478. vg 1.53 + 0.685. vg + 0.072 where Etot/Mb is in W kg-1 and vg is in m s-1. This equation is independent of body size, applying equally as well to a chipmunk or a quail as to a horse or an ostrich. In marked contrast, the metabolic energy consumed by each gram of an animal as it moves along the ground at a constant speed increases linearly with speed and is proportional to Mb-0.3. Thus, we have found that each gram of tissue of a 30 g quail or chipmunk running at 3 m s-1 consumes metabolic energy at a rate about 15 times that of a 100 kg ostrich, horse or human running at the same speed while their muscles are performing work at the same rate. Our measurements demonstrate the importance of storage and recovery of elastic energy in larger animals, but they cannot confirm or exclude the possibility of elastic storage of energy in small animals. It seems clear that the rate at which animals consume energy during locomotion cannot be explained by assuming a constant efficiency between the energy consumed and the mechanical work performed by the muscles. It is suggested that the intrinsic velocity of shortening of the active muscle motor units (which is related to the rate of cycling of the cross bridges between actin and myosin) and the rate at which the muscles are turned on and off are the most important factors in determining the metabolic cost of constant-speed locomotion. Faster motor units are recruited as animals increase speed, and equivalent muscles of small animals have faster fibres than those of larger animals. Also, the muscles are turned on and off more quickly as an animal increases speed, and at the same speed a small animal will be turning muscles on and off at a much higher rate. These suggestions are testable, and future studies should determine if they are correct.

Theoretical and empirical scaling patterns and topological homology in bone trabeculae.

1998 ◽  
Vol 201 (4) ◽  
pp. 573-590
Author(s):  
S M Swartz ◽  
A Parker ◽  
C Huo
Keyword(s):  
Body Size ◽  
Surface Area ◽  
Cancellous Bone ◽  
Structural Design ◽  
Theoretical Models ◽  
Small Animals ◽  
Bone Trabeculae ◽  
Large Animals ◽  
Vertebrate Skeleton ◽  
Area And Volume

Trabecular or cancellous bone is a major element in the structural design of the vertebrate skeleton, but has received little attention from the perspective of the biology of scale. In this study, we investigated scaling patterns in the discrete bony elements of cancellous bone. First, we constructed two theoretical models, representative of the two extremes of realistic patterns of trabecular size changes associated with body size changes. In one, constant trabecular size (CTS), increases in cancellous bone volume with size arise through the addition of new elements of constant size. In the other model, constant trabecular geometry (CTG), the size of trabeculae increases isometrically. These models produce fundamentally different patterns of surface area and volume scaling. We then compared the models with empirical observations of scaling of trabecular dimensions in mammals ranging in mass from 4 to 40x10(6)g. Trabecular size showed little dependence on body size, approaching one of our theoretical models (CTS). This result suggests that some elements of trabecular architecture may be driven by the requirements of maintaining adequate surface area for calcium homeostasis. Additionally, we found two key consequences of this strongly negative allometry. First, the connectivity among trabecular elements is qualitatively different for small versus large animals; trabeculae connect primarily to cortical bone in very small animals and primarily to other trabeculae in larger animals. Second, small animals have very few trabeculae and, as a consequence, we were able to identify particular elements with a consistent position across individuals and, for some elements, across species. Finally, in order to infer the possible influence of gross differences in mechanical loading on trabecular size, we sampled trabecular dimensions extensively within Chiroptera and compared their trabecular dimensions with those of non-volant mammals. We found no systematic differences in trabecular size or scaling patterns related to locomotor mode.

Bone strength in small mammals and bipedal birds: do safety factors change with body size?

1982 ◽  
Vol 98 (1) ◽  
pp. 289-301 ◽  
Author(s):  
A. A. Biewener
Keyword(s):  
Body Size ◽  
Small Mammals ◽  
Bending Strength ◽  
Published Data ◽  
Small Animals ◽  
Safety Factors ◽  
Cross Sectional ◽  
Limb Bones ◽  
Significant Difference ◽  
Large Animals

Measurements of the cross-sectional geometry and length of bones from animals of different sizes suggest that peak locomotory stresses might be as much as nine times greater in the limb bones of a 300 kg horse than those of a 0.10 kg chipmunk. To determine if the bones of larger animals are stronger than those of small animals, the bending strength of whole bone specimens from the limbs of small mammals and bipedal birds was measured and compared with published data for large mammalian cortical bone (horses and bovids). No significant difference (P greater than 0.2) was found in the failure stress of bone over a range in size from 0.05-700 kg (233 +/− 53 MN/m2 for small animals compared to 200 +/− 28 MN/m2 for large animals). This finding suggests that either the limb bones of small animals are much stronger than they need to be, or that other aspects of locomotion (e.g. duty factor and limb orientation relative to the direction of the ground force) act to decrease peak locomotory stresses in larger animals.

Energetics and mechanics of terrestrial locomotion. II. Kinetic energy changes of the limbs and body as a function of speed and body size in birds and mammals

1982 ◽  
Vol 97 (1) ◽  
pp. 23-40
Author(s):  
M. A. Fedak ◽  
N. C. Heglund ◽  
C. R. Taylor
Keyword(s):  
Body Size ◽  
Kinetic Energy ◽  
High Speed ◽  
Specific Power ◽  
Time Interval ◽  
Specific Rate ◽  
Centre Of Mass ◽  
X Ray ◽  
Terrestrial Locomotion ◽  
Integral Number

This is the second paper in a series examining the link between energetics and mechanics of terrestrial locomotion. In this paper, the changes in the kinetic energy of the limbs and body relative to the centre of mass of an animal (EKE, tot) are measured as functions of speed and body size. High-speed films (light or X-ray) of four species of quadrupeds and four species of bipeds running on a treadmill were analysed to determine EKE, tot. A mass-specific power term, EKE, tot/Mb was calculated by adding all of the increments in EKE during an integral number of strides and dividing by the time interval for the strides and body mass. The equations relating EKE, tot/Mb and speed were similar for all bipeds and quadrupeds regardless of size. One general equation for the rate at which muscle and tendons must supply energy to accelerate the limbs and body relative to the centre of mass seems to apply for all of the animals: E'KE, tot/Mb = 0.478 vg1.53 where E'KE, tot/Mb has the units W kg-1 and vg is ground speed in m s-1. Therefore, E'KE, tot/Mb does not change in parallel with the mass-specific rate at which animals consume energy (Emetab/Mb), either as a function of speed or as a function of body size.

EMPTY BODY WEIGHTS, CARCASS WEIGHTS AND OFFAL PROPORTIONS IN BULLS AND STEERS OF DIFFERENT MATURE SIZE

1984 ◽  
Vol 64 (1) ◽  
pp. 53-57 ◽  
Author(s):  
S. D. M. JONES ◽  
R. E. ROMPALA ◽  
J. W. WILTON ◽  
C. H. WATSON
Keyword(s):  
Body Weight ◽  
Small Animal ◽  
High Energy ◽  
Carcass Weight ◽  
Small Animals ◽  
Beef Steers ◽  
Body Weights ◽  
Breed Crosses ◽  
Large Animals ◽  
Animal Size

Empty body weights, carcass weights and offal proportions were compared in 33 young beef bulls and 33 beef steers of different mature body size (35 small or mainly British breed crosses, 31 large or Continental crosses). All cattle were fed a high energy diet based on corn silage and high moisture corn from weaning to slaughter. Slaughter was carried out once 6 mm of fat had been attained at the 11/12th ribs, determined ultrasonically. Feed was removed 24 h and water 16 h prior to slaughter. The offal components were all weighed fresh and the alimentary components emptied of digesta. Bulls weighed 8.0% heavier (P < 0.05) than steers at slaughter, while large animals were 38.7% heavier (P < 0.0001) than small animals. Bulls and large animals had carcasses that dressed out 1.5% heavier than steers and small animals. To eliminate the effect of gutfill, carcass weights and offal components were expressed as a proportion of empty body weight. Bulls had a higher proportion of warm carcass weight and lower proportions of liver, spleen, heart, lungs, rumen, abomasum, large intestine and front feet relative to empty body weight than steers. Large animals had a greater proportion of warm carcass weight and hind feet, and a lower proportion of head, hide, liver, kidneys, omasum and small intestine relative to empty body weight than small animals. All castration by size interactions for liveweight, carcass weight, empty body weight and offal proportions were not significant. Castration and small animal size both increased the proportion of noncarcass parts relative to empty body weight in animals slaughtered at similar finish. Key words: Body, carcass, offal, bull, steer, maturity

The Role of the ‘Walking Legs’ in Aquatic and Terrestrial Locomotion of the Crayfish Austropotamobius Pallipes (Lereboullet)

1975 ◽  
Vol 62 (2) ◽  
pp. 447-454 ◽  
Author(s):  
CAROLINE M. POND
Keyword(s):  
The Body ◽  
Hydrodynamic Drag ◽  
Terrestrial Locomotion ◽  
Austropotamobius Pallipes ◽  
The Third ◽  
Fourth Pair

1. The hydrodynamic drag acting on the crayfish Austropotamobius pallipes is measured and it is concluded that, in the range of velocities used in walking, the drag is independent of the posture of the limbs and the direction of motion of the body. At swimming velocities the streamlining caused by promotion of the legs reduces the drag losses to half that of a crayfish moving in the forwards walking posture at the same speed. 2. The forwards walking of intact crayfish is compared with that of the same animal after amputation of one or more pairs of legs. It is concluded that the third and fourth pair of legs provide most of the propulsion under water and the second pair is not essential to locomotion under any of the conditions tried.

scholarly journals Evolutionary cascades induced by large frugivores

2017 ◽  
Vol 114 (45) ◽  
pp. 11998-12002 ◽  
Author(s):  
Jedediah F. Brodie
Keyword(s):  
Tropical Forests ◽  
Fruit Size ◽  
Peninsular Malaysia ◽  
Fruit Color ◽  
Small Animals ◽  
Fruit Traits ◽  
Frugivorous Birds ◽  
Large Animals ◽  
Evolutionary Consequences ◽  
Morphologic Changes

Large, fruit-eating vertebrates have been lost from many of the world’s ecosystems. The ecological consequences of this defaunation can be severe, but the evolutionary consequences are nearly unknown because it remains unclear whether frugivores exert strong selection on fruit traits. I assessed the macroevolution of fruit traits in response to variation in the diversity and size of seed-dispersing vertebrates. Across the Indo-Malay Archipelago, many of the same plant lineages have been exposed to very different assemblages of seed-dispersing vertebrates. Phylogenetic analysis of >400 plant species in 41 genera and five families revealed that average fruit size tracks the taxonomic and functional diversity of frugivorous birds and mammals. Fruit size was 40.2–46.5% smaller in the Moluccas and Sulawesi (respectively), with relatively depauperate assemblages of mostly small-bodied animals, than in the Sunda Region (Borneo, Sumatra, and Peninsular Malaysia), with a highly diverse suite of large and small animals. Fruit color, however, was unrelated to vertebrate diversity or to the representation of birds versus mammals in the frugivore assemblage. Overhunting of large animals, nearly ubiquitous in tropical forests, could strongly alter selection pressures on plants, resulting in widespread, although trait-specific, morphologic changes.

Intermittent exercise alters endurance in an eight-legged ectotherm

1992 ◽  
Vol 262 (5) ◽  
pp. R852-R859 ◽  
Author(s):  
R. B. Weinstein ◽  
R. J. Full
Keyword(s):  
Intermittent Exercise ◽  
Fold Increase ◽  
Muscle Lactate ◽  
Average Speed ◽  
Terrestrial Locomotion ◽  
Continuous Exercise ◽  
Total Distance ◽  
Exercise Period ◽  
Rate Of Oxygen Consumption ◽  
Continuous Running

Most animals move intermittently, yet many proposed performance limitations of terrestrial locomotion are based on steady-state measurements and assumptions. We examined the effect of work-rest transitions by exercising the ghost crab, Ocypode quadrata (28.1 +/- 8.1 g), intermittently on a treadmill at 0.30 m/s, a supramaximal speed [i.e., greater than the speed that elicits the maximal rate of oxygen consumption (VO2)]. Duration of the exercise and pause periods, ratio of exercise to pause, and speed during the exercise period were varied to determine the effect on performance. Crabs fatigued after 7.5 min of continuous running, a distance capacity (i.e., total distance traveled before fatigue) of 135 m. When the task was done intermittently with 2-min exercise and 2-min pause periods, the crabs fatigued after 87 min (a total distance of 787 m), representing an 5.8-fold increase in distance capacity compared with continuous exercise at the same absolute speed (0.30 m/s) and a 2.2-fold increase in distance capacity compared with continuous exercise at the same average speed (0.15 m/s). Pause periods less than 30 s did not result in greater distance capacity compared with continuous exercise at the same average speed. Longer (3-5 min) and shorter exercise periods (less than or equal to 30 s) decreased distance capacity. Leg muscle lactate increased 10-fold to 15 mumol/g leg during intermittent exercise. However, significant amounts of lactate were cleared from the leg during the brief pause periods.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals WHAT IS THE LENGTH OF A SNAKE?

2008 ◽  
pp. 1-3 ◽  
Author(s):  
Jesus A. Rivas ◽  
Rafeal E. Ascanio ◽  
Maria D. C. Munoz
Keyword(s):  
Large Range ◽  
Small Animals ◽  
Live Animal ◽  
Actual Length ◽  
Total Length ◽  
Large Animals ◽  
The Way

The way that herpetologists have traditionally measuredlive snakes is by stretching them on a ruler andrecording the total length (TL). However, due to the thinconstitution of the snake, the large number of intervertebraljoints, and slim muscular mass of most snakes,it is easier to stretch a snake than it is to stretch anyother vertebrate. The result of this is that the length ofa snake recorded is infl uenced by how much the animalis stretched. Stretching it as much as possible is perhapsa precise way to measure the length of the specimenbut it might not correspond to the actual length ofa live animal. Furthermore, it may seriously injure a livesnake. Another method involves placing the snake in aclear plexiglass box and pressing it with a soft materialsuch as rubber foam against a clear surface. Measuringthe length of the snake may be done by outlining itsbody with a string (Fitch 1987; Frye 1991). However, thismethod is restricted to small animals that can be placedin a box, and in addition, no indications of accuracy of thetechnique are given. Measuring the snakes with a fl exibletape has also been reported (Blouin-Demers 2003)but when dealing with a large animals the way the tapeis positioned can produce great variance on the fi nal outcome.In this contribution we revise alternative ways tomeasuring a snake and propose a method that offers repeatableresults. We further analyze the precision of thismethod by using a sample of measurements taken fromwild populations of green anacondas (Eunectes murinus)with a large range of sizes.

Inheritance of geographic variation in body size, and countergradient variation in growth rates, in the southern brown bandicoot Isoodon obesulus.

2000 ◽  
Vol 22 (1) ◽  
pp. 9 ◽  
Author(s):  
ML Hale
Keyword(s):  
Growth Rate ◽  
Body Weight ◽  
Body Size ◽  
Geographic Variation ◽  
Growth Rates ◽  
Habitat Type ◽  
Adaptive Divergence ◽  
Common Environment ◽  
Countergradient Variation ◽  
Large Animals

The inheritance of geographic variation in body size in the southern brown bandicoot (Isoodon obesulus) was investigated through a common-environment crossbreeding experiment. The geographic variation in body size is related to habitat type, suggesting that it may be adaptive. Adults from two locations in Western Australia, Perth (large animals) and Albany (small animals), were collected and offspring from both hybrid and non-hybrid matings were reared under controlled conditions. All four variables examined (head length, pes length, ear length and body weight) were found to possess a large genetic component, supporting the interpretation that the geographic variation in size is adaptive. The three length variables initially showed additive genetic variation, although the variation in body weight displayed dominance. Genetically controlled differences in growth rate were also detected, with the smaller animals, found in the relatively poorer environment, possessing the faster intrinsic growth rate. Thus, not only does there appear to be adaptive divergence in initial body size, but the countergradient variation in growth rates provides additional evidence for adaptive divergence in this species.

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