Spiders on a treadmill: influence of running activity on metabolic rates in<i>Pardosa lugubris</i>(Araneae, Lycosidae) and<i>Marpissa muscosa</i>(Araneae, Salticidae)

SUMMARY This is the first study to examine the direct metabolic costs of autotomy,the voluntary shedding of an appendage as an escape mechanism, in invertebrates. We investigated the effects of limb autotomy upon endurance and metabolic cost of locomotion in the field cricket Gryllus bimaculatus. Compared with control (intact) crickets, animals that had autotomised a single hindlimb were slower, stopped more often, moved a shorter distance and expended more energy doing so. Both the cost of locomotion (COT)and minimal cost of locomotion (MCOT) were significantly higher for autotomised animals. We compare these data with locomotion energetics of 36 other invertebrate species, and discuss the results in terms of the biomechanics of walking in crickets.

Section: Respirometrymentioning

confidence: 59%

Section: Table·3 Comparative Data For the Energetics Of Locomotion Imentioning

confidence: 62%

Just drop it and run: the effect of limb autotomy on running distance and locomotion energetics of field crickets (Gryllus bimaculatus)

Fleming

Bateman

2007

“…Spiders forced to exercise can increase metabolic rate to approximately four to 10 times above rest (Seymour and Vinegar, 1973;Schmitz, 2005). It may be significant that A. aquatica enlarge the diving bell under conditions when metabolic rate would be expected to rise.…”

Section: Discussion Effectiveness Of the Physical Gillmentioning

confidence: 99%

The diving bell and the spider: the physical gill of Argyroneta aquatica

Seymour

Hetz

2011

120

111

SUMMARYArgyroneta aquatica is a unique air-breathing spider that lives virtually its entire life under freshwater. It creates a dome-shaped web between aquatic plants and fills the diving bell with air carried from the surface. The bell can take up dissolved O 2 from the water, acting as a 'physical gill'. By measuring bell volume and O 2 partial pressure (P O2 ) with tiny O 2 -sensitive optodes, this study showed that the spiders produce physical gills capable of satisfying at least their resting requirements for O 2 under the most extreme conditions of warm stagnant water. Larger spiders produced larger bells of higher O 2 conductance (G O2 ). G O2 depended on surface area only; effective boundary layer thickness was constant. Bells, with and without spiders, were used as respirometers by measuring G O2 and the rate of change in P O2 . Metabolic rates were also measured with flow-through respirometry. The water-air P O2 difference was generally less than 10kPa, and spiders voluntarily tolerated low internal P O2 approximately 1-4kPa before renewal with air from the surface. The low P O2 in the bell enhanced N 2 loss from the bell, but spiders could remain inside for more than a day without renewal. Spiders appeared to enlarge the bells in response to higher O 2 demands and lower aquatic P O2 .

“…Also, the high number of limbs ensures an increased locomotor versatility on uneven and rough terrains, particularly in the likely unawareness of eachterrain roughnesses (Klaassen et al, 2002). Despite all of these reasons, scientific research on eight-legged locomotion is rather sparse and only a few papers (Herreid and Full, 1980;Schmitz, 2005a;Schmitz, 2005b;Sensenig and Schultz, 2006;Ward and Humphreys, 1981a;Wilson, 1967) have addressed spider gaits in detail.…”

Section: Introductionmentioning

confidence: 99%

Biomechanics of octopedal locomotion: kinematic and kinetic analysis of the spiderGrammostola mollicoma

Biancardi

Fábrica

Polero

et al. 2011

SUMMARYDespite the abundance of octapodal species and their evolutionary importance in originating terrestrial locomotion, the locomotion mechanics of spiders has received little attention so far. In this investigation we use inverse dynamics to study the locomotor performance of Grammostola mollicoma (18g). Through 3-D kinematic measurements, the trajectory of the eight limbs and cephalothorax or abdomen allowed us to estimate the motion of the body centre of mass (COM) at different speeds. Classic mechanics of locomotion and multivariate analysis of several variables such as stride length and frequency, duty factor, mechanical external work and energy recovery, helped to identify two main gaits, a slow (speed <11cms -1 ) one and a fast one characterised by distinctive 3-D trajectories of COM. The total mechanical work (external + internal) calculated in the present study and metabolic data from the literature allowed us to estimate the locomotion efficiency of this species, which was less than 4%. Gait pattern due to alternating limb support, which generates asymmetrical COM trajectories and a small but consistent energy transfer between potential and kinetic energies of COM, is discussed both in terms of coordination indices and by referring to the octopod as formed by two quadrupeds in series. Analogies and differences of the newly obtained parameters with the allometric data and predictions are also illustrated. Supplementary material available online at