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Walking And Running In The Red-Legged Running Frog, Kassina Maculata, Anna N. Ahn, E Furrow, Andrew A. Biewener
Walking And Running In The Red-Legged Running Frog, Kassina Maculata, Anna N. Ahn, E Furrow, Andrew A. Biewener
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Although most frog species are specialized for jumping or swimming, Kassina maculata (red-legged running frog) primarily uses a third type of locomotion during which the hindlimbs alternate. In the present study, we examined Kassina's distinct locomotory mode to determine whether these frogs walk or run and how their gait may change with speed. We used multiple methods to distinguish between terrestrial gaits: the existence or absence of an aerial phase, duty factor, relative footfall patterns and the mechanics of the animal's center of mass (COM). To measure kinematic and kinetic variables, we recorded digital video as the animals moved …
A Motor And A Brake: Two Leg Extensor Muscles Acting At The Same Joint Manage Energy Differently In A Running Insect, Anna N. Ahn, Robert J. Full
A Motor And A Brake: Two Leg Extensor Muscles Acting At The Same Joint Manage Energy Differently In A Running Insect, Anna N. Ahn, Robert J. Full
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The individual muscles of a multiple muscle group at a given joint are often assumed to function synergistically to share the load during locomotion. We examined two leg extensors of a running cockroach to test the hypothesis that leg muscles within an anatomical muscle group necessarily manage (i.e. produce, store, transmit or absorb) energy similarly during running. Using electromyographic and video motion-analysis techniques, we determined that muscles 177c and 179 are both active during the first half of the stance period during muscle shortening. Using the in vivo strain and stimulation patterns determined during running, we measured muscle power output. …
Energy Absorption During Running By Leg Muscles In A Cockroach, Robert J. Full, Darrell R. Stokes, Anna N. Ahn, Robert K. Josephson
Energy Absorption During Running By Leg Muscles In A Cockroach, Robert J. Full, Darrell R. Stokes, Anna N. Ahn, Robert K. Josephson
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Biologists have traditionally focused on a muscle's ability to generate power. By determining muscle length, strain and activation pattern in the cockroach Blaberus discoidalis, we discovered leg extensor muscles that operate as active dampers that only absorb energy during running. Data from running animals were compared with measurements of force and power production of isolated muscles studied over a range of stimulus conditions and muscle length changes. We studied the trochanter-femoral extensor muscles 137 and 179, homologous leg muscles of the mesothoracic and metathoracic legs, respectively. Because each of these muscles is innervated by a single excitatory motor axon, …
Static Forces And Moments Generated In The Insect Leg: Comparison Of A Three-Dimensional Musculo-Skeletal Computer Model With Experimental Measurements, Robert J. Full, Anna N. Ahn
Static Forces And Moments Generated In The Insect Leg: Comparison Of A Three-Dimensional Musculo-Skeletal Computer Model With Experimental Measurements, Robert J. Full, Anna N. Ahn
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As a first step towards the integration of information on neural control, biomechanics and isolated muscle function, we constructed a three-dimensional musculo-skeletal model of the hind leg of the death-head cockroach Blaberus discoidalis. We tested the model by measuring the maximum force generated in vivo by the hind leg of the cockroach, the coxa-femur joint angle and the position of this leg during a behavior, wedging, that was likely to require maximum torque or moment production. The product of the maximum force of the leg and its moment arm yielded a measured coxa-femur joint moment for wedging behavior. The …
Moderate Dehydration Decreases Locomotor Performance Of The Ghost Crab, Ocypode Quadrata, Randi B. Weinstein, Robert J. Full, Anna N. Ahn
Moderate Dehydration Decreases Locomotor Performance Of The Ghost Crab, Ocypode Quadrata, Randi B. Weinstein, Robert J. Full, Anna N. Ahn
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The effect of dehydration on the aerobic metabolism and endurance of sustained, terrestrial locomotion was determined for the ghost crab, Ocypode quadrata, The rate of evaporative water loss, measured as the percentage of decrease in body mass per hour, was influenced by ambient temperature (Tₐ), Increasing Tₐ from 24° C to 30° C (40%-50% relative humidity) increased the rate of water loss from 2.3% hˉ¹ ± 0.2% hˉ¹ to 3.6% hˉ¹ ± 0.6% hˉ¹. Crabs were divided into three treatment groups to determine the effect of dehydration on aerobic metabolism: hydrated control crabs, slowly dehydrated crabs, and rapidly dehydrated …
Decreased Sprint Speed As A Cost Of Reproduction In The Lizard Scelopours Occidentalis: Variation Among Populations, Barry Sinervo, Richard Hedges, Stephen C. Adolph
Decreased Sprint Speed As A Cost Of Reproduction In The Lizard Scelopours Occidentalis: Variation Among Populations, Barry Sinervo, Richard Hedges, Stephen C. Adolph
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Decreased mobility of gravid females is thought to be an important cost of reproduction in lizards. We measured sprint speeds of female western fence lizards (Sceloporus occidentalis Baird and Girard) before and after they had oviposited. Females from two California populations were about 20% slower when gravid, females from an Oregon population were about 30% slower, and females from a Washington population were about 45% slower, compared to their speeds after recovering from reproduction. The decrease in sprint speed persisted for several weeks after oviposition, suggesting that reproduction impairs sprint performance by affecting body condition in addition to the burdening …