To illustrate parameters that differed between leg pairs, we calculated mean values for a given pair of legs (L1 and R1; L2 and R2; L3 and R3; Fig. They found that the hirsute ants reflected 67 percent of incoming light in the near-infrared and visible spectrum, while hairless ants scattered only 41 percent of that light. This resulted in a not quite synchronous transition between swing and stance phases of the legs in one tripod group. Absolute leg length per se would appear to limit stride length in C. bombycina, unless stride length is increased by inserting aerial phases into the walk. They found that the ants with hair had body temperatures 5 to 10 degrees lower than those that had been shaved a big difference in the scorching Sahara. In silver ants, stride frequency levelled off beyond speeds of 150200mms1 towards a value of 40Hz. First, this coordination results in brief, synchronous and forceful impacts of three legs on the sand substrate, which may serve to minimize sinking into the yielding dune sand (Li et al., 2009). The authors declare no competing or financial interests. We expanded the range of recorded walking speeds in C. bombycina beyond the known limits (Wehner, 1983; Zollikofer, 1994), to more than 800mms1, and assessed the contribution of different spatial and temporal walking parameters to achieve such speeds and examined in detail gait and leg coordination patterns to gain a deeper understanding of the silver ant's walking behaviour. The legs of one tripod group exhibit almost perfect synchrony in the timings of their lift-offs and touch-downs, and good tripod coordination is present over the entire walking speed range (tripod coordination strength values around 0.8). To calculate stride frequency, we divided walking speed by stride length. These high frequencies are achieved by very short stance phases and fast swing speeds. In comparison to C. fortis, C. bombycina thus have their tarsal ground contacts closer to the body. For example, in a given video frame, L1, R2, L3 may be in swing phase, and R1, L2, R3 in stance phase. Maybe one day you will have a fur coat with silver hairs, muses Wehner. (NO AWARD), 2019. unless you renew or The reversal point, with phase durations being about equal, was at a walking speed of about 100mms1 in C. bombycina and about 180mms1 in C. fortis. For all evaluated recordings, the mean walking speed was calculated as the distance covered from the start of the first step cycle to the end of the last step cycle in a given video sequence, divided by the time needed to cover that distance. Gait indexing does not consider a continuous gait, such as a tripod gait, but rather assigns each frame in a video recording an index number according to the momentary leg coordination in that frame (see Fig. Swing and stance phase onset of the three legs in a tripod group occurred almost simultaneously. Leg lengths in C. bombycina were even smaller compared with those of C. fortis. 6A shows an example of a podogram and corresponding gait indexing for C. bombycina; Fig. Leg coordination parameters. To exploit this foraging niche, silver ants need to withstand the extremely hot and dry desert environment. This message will appear once per week Using electron microscopy, Columbia physicist Nanfang Yu and colleagues were able to see the triangular structure of those hairs. ; Writing - review & editing: H.W. Rather than face predators during cooler hours, silver ants only emerge from their dens at the hottest point in a Saharan day. We next analysed the spatial properties of locomotion in C. bombycina regarding footfall patterns (Fig. Calculating relative walking speed, typically in body lengths per second, appears more adequate when analysing parameters related to body size such as stride length or stride amplitude. Cataglyphisbombycina showed footfall positions closer to the body when compared with C. fortis, consistently in AEPs and PEPs of all legs. These include special epicuticular hydrocarbons, a favourable volume-to-surface relationship (at least for an insect), a slender alitrunk, powerful muscles and long legs (relative to other ants of more temperate climates) (Sommer and Wehner, 2012; Wehner and Wehner, 2011; Lenoir et al., 2009). Our work isn't possible without your support. S3. After all, long legs have high momentums of inertia, in small arthropods as well as in large mammals (Heglund et al., 1974; Heglund and Taylor, 1988). This is very, very unique, Yu says. These values were higher than TCS values recorded in C. fortis, especially at slow walking speeds. Ants were usually recorded up to 5 times at different temperatures in order to obtain different walking speeds. Interestingly, this holds true when calculating maximum relative stride length (stride length/alitrunk length), resulting in 2.34 and 2.41 for C. bombycina and C. fortis, respectively. Anterior extreme positions (AEP) are shown for the left body side (L1, left front leg; L2, left middle leg; L3, left hind leg); posterior extreme positions (PEP) are shown for the right body side (R1, right front leg; R2, right middle leg, R3 right hind leg). Its very interesting to see that the same mechanism [engineered] by humans is also used by animals to deal with harsh weather.. 6C provides an example for C. fortis, recorded at similar walking speeds (about 350mms1). Motor flexibility in insects: adaptive coordination of limbs in locomotion and near-range exploration, Heat shock protein synthesis and thermotolerance in Cataglyphis, an ant from the Sahara desert, A behavioural analysis of the temporal organisation of walking movements in the 1st instar and adult stick insect (Carausius morosus). The relatively short legs may thus contribute to C. bombycina reaching a 40Hz stride frequency, while the longer-legged C. fortis achieves just about 30Hz. But at mid-infrared wavelengths, those same hairs allow excess heat to be re-emitted in a process called black body radiation effectively cooling the ants by radiating away heat. Standard deviations of footfall positions were used to quantify the spread of footprint positions (footprint clustering in Fig. 4, and the corresponding regression line equations with slope and intercept values are stated in the figure legend.

Parts of the latter dataset and corresponding analyses have been published previously (Wahl et al., 2015). And while absorption may sound counterproductive, it actually helps the ants cool down as long as the sky is clear, as it often is in the Sahara. So there is a net radiative energy flow from the hot ant to the clear sky. Sign up to read our regular email newsletters, Full metal jacket: the silver ant shimmers in the heat (Image: Norman Nan Shi and Nanfang Yu, Columbia Engineering). Among other unique adaptations, this tenacious bug uses shimmering, silver hairs to lower its body temperature a process described for the first time by Columbia University researchers in Thursdays edition of Science Magazine. The concept of gait continuum has been linked to several coordination rules derived from behavioural experiments (Cruse, 1990; Drr et al., 2018) that were verified by successful implementation in hexapod walking models and machines (Schilling et al., 2013). Cataglyphisbombycina was statistically significantly smaller than C. fortis, regarding all the absolute length measurements. All measurements were digitized with ImageJ (National Institutes of Health, Bethesda, MD, USA) in a frame-by-frame video analysis. Known as thermophilic scavengers, these ants collect corpses of other insects [mostly flies] that have succumbed to the heat stress, says Rdiger Wehner, a professor at the Brain Research Institute at the University of Zrich, Switzerland, whos been studying heat-tolerant ant species for nearly four decades. ), with relative speeds of up to 377 and 171 body lengths per second, respectively (Rubin et al., 2016; Kamoun and Hogenhout, 1996). Leg coordination parameters are of secondary importance for speed production, but they are of course essential for static and dynamic stability (e.g. honey ant pot desert The sequence of swing and stance movements of the six legs was visualized by podograms (Fig. Select stories from the Monitor that empower and uplift. 4G,H) and by corresponding angular velocities of the femur (table below Fig. The more the TCS value approaches 0, the less synchronous are the swing movements in a tripod group. The differences in the lateral deviations in consecutive frames were used to calculate lateral velocity. Video analysis across a broad range of locomotor speeds revealed several differences to C. fortis. The relationships of the different parameters within a species were close to isometry for both species (Fig. Your session to The Christian 6 legend; Fig. For each footfall position, 10 videos with three step cycles each were evaluated, with walking speeds of 490600mms1 for C. bombycina and 490580mms1 for C. fortis. These highly mobile ants endure the extreme temperatures of their sand dune environment with outstanding behavioural, physiological and morphological adaptations. Apparently, ants build rafts. Cataglyphisfortis is a thermophilic scavenger (Wehner, 2016), much like C. bombycina, although it lives in North African salt pan habitats that typically exhibit baked salty clay substrates in the summer months, as opposed to the sand dune habitat of C. bombycina. Forward acceleration is the respective change of forward speed within a 1ms time interval (see FigsS4 and S5A,B). This is achieved by overlapping swing movements of the two tripod groups, partly as a result of the high synchrony of the leg movements within a tripod. S1 and TableS1). far lower than in C. fortis, where aerial phases occur at about 370mms1 and above. The swing phase was considered to be the time between tarsal touch-down and lift-off; that is, the time of tarsal tip movement. In the silver ant, aerial phases thus occur well before maximum stride lengths or stride frequencies are reached. Cataglyphis bombycina, better known as the silver ant of the Saharan desert, the Sinai and the deserts of the Arabian Peninsula, occupies the niche of a thermophilic scavenger. In our new Conversation, she talks about her fieldwork in Indonesia, Costa Rica, the Dominican Republic and the Appalachian Mountains, including a death-defying dash to the top of a mountain through an approaching hurricane. (C) Tripod gait in C. bombycina.



The middle legs were lifted together with the front and hind legs of their tripod group, but they started the transition towards stance phase slightly earlier (1.7ms) than the front and hind legs. Cataglyphisbombycina is significantly smaller than C. fortis with respect to mean alitrunk length (11% smaller; t-test, ***P<0.001) and mean leg length (first leg pair, 19% shorter, t-test, ***P<0.001; second leg pair, 18% shorter, U-test, ***P<0.001; third leg pair, 18% shorter, U-test, ***P<0.001). Stick insects are textbook examples demonstrating the entire spectrum of the gait continuum from pentapod to tetrapod to tripod coordination with increasing walking speed (Wilson, 1966; Graham, 1972). Zollikofer, 1988). During the hottest hours of the day, the surface temperature of the Saharan sand may easily exceed 60C (Wehner et al., 1992) and desiccation stress reaches its maximum with very high water vapour saturation deficits (Lighton and Wehner, 1993). This is almost half the minimum stance phase duration in C. fortis of 12ms.

The ants have 10 minutes to find food before they fry (Image: Vincent Amouroux, Mona Lisa production/ Science Photo Lab). All rights reserved. Duty factor is the duration of the stance phase of a leg divided by the entire duration of the respective step cycle, stance and swing phase together. For pairwise comparisons of normally distributed data, we used the t-test; for non-normally distributed data, we used the MannWhitney U-test (U-test). Colour index analyses (Bi,Di) are shown as normalized frequency plots, and number index data (Bii,Dii) as averaged index numbers (ordinates) for the respective walking speed bins (abscissae). Different from stride length, stride amplitude was defined as the distance covered by a swing movement of the leg in body coordinates (Wosnitza et al., 2013). Bob is a news reporter for Science in Portland, Oregon,covering chemistry, materials science, and energy stories. Applications are now open to propose Workshops for 2024, 30 Broad Street, Suite 801 6 legend). There are two related potential advantages of this leg movement pattern. Duty factor is an indirect indicator of the occurrence of aerial phase, compared with gait indexing, for example. The petiole can be regarded as the centre of mass (COM) of an ant (see Reinhardt and Blickhan, 2014). Can noxious beetle bursts make better engines? in stick insects: Wendler, 1964). High-speed videos of Cataglyphis bombycina and Cataglyphis fortis locomotion are available from ResearchGate: doi:10.13140/RG.2.2.21093.45282 and doi:10.13140/RG.2.2.12704.84488. In C. fortis, there was a continuous change in gait pattern composition across the entire walking speed range, from the <50mms1 bin to the <650mms1 bin (Fig. Cataglyphisbombycina combines high stride frequencies, short stance phases and fast swing movements to achieve high running speeds, together with the high synchrony of the legs in a tripod. To confirm that the hairs were key, the team shaved some ant specimens and then exposed both shaved and hairy ants to a hot xenon lamp and a cold plate that simulated sun and sky. All six legs were severed in the coxathorax joints before measurement. In line with the SLIP model (Blickhan and Full, 1993), leg synchronization in C. bombycina increases vertical forces and vertical amplitudes of the COM which might lead to increased elastic energy storage in the legs. To determine the walkrun transition in these cases, in the absence of aerial phases, further analysis is required such as ground reaction force patterns, energy transfer between the legs and body, and energy fluctuation patterns of the COM. All rights reserved. This is slightly below the minimum of 19ms in C. fortis. Although these ants are known for their distinctive shiny coat, it was unclear before now whether the hairs played a role in temperature regulation. Angular velocity (degs1) was calculated for representative sample steps as the angular deviation of the femur (with respect to body axis) during one swing movement. Stride amplitude can be estimated by subtracting body displacement (BD) from stride length (SL) for the respective swing phase (stride amplitude=SLBD). Surprisingly, C. bombycina has comparatively shorter legs than its well-studied sister species Cataglyphis fortis from salt pan habitats. Channel walls were painted with matt grey varnish to avoid distracting reflections. Regression lines of the swing speed versus walking speed graphs tended to exhibit slightly lower slopes in C. bombycina. Help News from Science publish trustworthy, high-impact stories about research and the people who shape it. For fast walking speeds, tripod coordination is typically observed, with three legs simultaneously in swing and three legs in stance phase, coupling the front and hind legs of one body side and the middle leg of the other body side into a tripod group. Subsequent computer modeling showed that the hairs prismatic structure and arrangementthat is, paralleling but not touching the bodyenhance reflection by trapping incoming light and scattering it outward in all directions. The duty factor represents that fraction of step cycle duration that is occupied by the stance phase, when the body is supported by a given leg. However, the slopes of the linear regression lines (C. bombycina: y=0.02x+4.72; C. fortis: y=0.02x+6.04) and the range of stride lengths (4.521mm) were quite comparable between the two species. They also climb on rocks and dead vegetation above the hot sand for breaks in cooler air higher up. And the ants have another trick up their sleeve: they are hairy on their top and sides, but not underneath, where their hair would be detrimental as it would absorb the infrared radiation from the hot sand that it normally emits towards the cooler sky. 5Bii) during the step cycle, with the left hind leg (L3) serving as reference (and thus without data point scatter in the diagrams). Summer in the Sahara is scorchingsand temperatures can range between 149-158 degrees Fahrenheit. High synchrony of the legs in a tripod results in a walking pattern in C. bombycina that is strongly reminiscent of bipedal locomotion, though, with the alternating tripods representing the two legs. 6B) and C. fortis (Fig. 5B). (B) Cataglyphisfortis in a salt pan near Menzel Chaker, Tunisia. Its kind of remarkable and pretty cool no pun intended that theres an analogue in nature to the way were thinking about these problems, Raman says. Walking behaviour of C. bombycina (Fig. The silver ant has evolved several adaptations to cope with the extreme heat, including a trait that inspired its name: hairs that glint silver in sunlight, and that densely coat its back and sides. The middle legs assumed a duty factor below 0.5 last, indicative of the final transition from walking to running, at about 120mms1. Movement of the COM was tracked to analyse its horizontal velocity and acceleration (see FigsS4 and S5). subscription yet. 3A; cf. My work in Kenya, for example, was heavily influenced by a Christian Science Monitor article I had forced myself to read 10 years earlier. There was a clear tendency for the hind leg in a tripod to be lifted off the ground first, followed by the front leg and the middle leg performing stanceswing transition last. Other fast running arthropods do not show such high synchronization [e.g. Sahara silver ants forage in the midday sun and look like droplets of mercury rolling on the desert surface. (EH) Individual values for the three leg pairs (Lp1, front legs; Lp2, middle legs; Lp3, hind legs). The floor was coated with fine sand (0.10.4mm particle size) to provide a slip-free substrate for normal walking behaviour. Study species and high-speed video recording. It thus indicates by how much a leg's swing movement exceeds the respective body movement during the swing. The shorter legs, and resulting smaller stride lengths, of C. bombycina appear to be compensated for in this way. In summary, C. bombycina apparently reaches high running speeds by having high stride frequencies of more than 40Hz. They do this to a larger extent than C. fortis, a fact that was further demonstrated by measuring stride amplitude. you are agreeing to our, One month free trial to theMonitorDaily, Courtesy of Norman Nan Shi and Nanfang Yu, Are you scientifically literate? The generation of box-and-whisker plots, normality tests and statistical pairwise and multiple comparisons were performed in SigmaPlot 11.0 (Systat Software Inc., San Jose, CA, USA). Observed values were mostly between 0.7 and 0.9, clustering around 0.8. improve functionality and performance. Swing and stance phase durations (Fig. The question of how C. bombycina silver ants renowned for their high speeds walk across a large range of speeds will be addressed below. The ants have a suite of adaptations to help them survive in the desert, including long legs and heat shock proteins. The highest measured frequency in C. fortis was 36Hz at 596mms1. 4A) increased from 4.7mm (at 73mms1) to 20.8mm (at 618mms1) in C. bombycina; that is, stride length more than quadrupled. 4AD), particularly in cases where no significant differences were observed between leg pairs. How can the UK keep homes cool without air conditioning? During the hottest part of the day, tiny hairs on the back of the Saharan silver ant repel the suns rays and also shed excess heat back toward the sky.

A piece of millimetre grid paper was used for calibration before a set of videos was recorded. We found that there was a very close correlation between the two studies, Yu says. You can only expect to see such extreme engineering in the biological world in such harsh environments.. After meeting at a conference, Yu and Dr. 6Bi). continue to use the site without a Both aspects were observed in the present comparison of ant species. 1C). Youll get the Monitor Weekly magazine, the Monitor Daily email, and unlimited access to CSMonitor.com. Were about kicking down the door of thought everywhere and saying, You are bigger and more capable than you realize. It is outperformed according to our present knowledge by very few species, most notably a Californian coastal mite (Paratarsotomus macropalpis) and an Australian tiger beetle (Cicindela sp. Were known as being fair even as the world becomes as polarized as at any time since the newspapers founding in 1908. The three most recent Christian Science articles with a spiritual perspective. The experiments were conducted in compliance with current laws, regulations an ethical guidelines of the University of Ulm and of the country where they were performed. Ant-Mans cool. Box-and-whisker plots show the median as the box centre, the 25th and 75th percentiles as box margins and the and 90th percentiles as whiskers. The Saharan silver ant, or Cataglyphis bombycina, is a case study in extremes. But sometimes the simple efficiency of biological systems can give human tech a run for its money. *This article was updated on August 11, 2015, to reflect the following change: An earlier version stated that, in the mid-infrared, the ants hair actually functions as a vacuum medium. The phrase has been updated to indicate that the hairs function as an anti-reflective coating (similar to what you might find on eyeglasses to reduce glare or reflection). Another feature, producing C. bombycinas typical silvery appearance, is triangularly shaped hairs with thermoregulatory effects (Shi et al., 2015; Willot et al., 2016). The researchers then used spectrometers to measure light reflection in ant specimens with their hairs intact, as well as specimens whose hair had been removed. But theyre much smaller than mid-infrared wavelengths of light, which means they form a dull surface that can glow and emit light instead of reflecting it. We characterized the silver ants' walking behaviour by further gait analyses. A weekly update on music, movies, cultural trends, and education solutions. Phase plots analyse the phase coordination of the six legs in a circular step cycle diagram. In C. fortis, by contrast, a special role of the middle legs (Fig. We know that Saharan silver ants (Cataglyphis bombycina) are extremely heat tolerant, and that they eke out a living in their formidable habitat. ; Investigation: S.E.P., V.L.W. Tracks of leg movements and footfall geometry measurements were performed in ImageJ (National Institutes of Health). The results paint a stark picture of natural efficiency: By interacting with different types of electromagnetic radiation, silver hairs actually had a cooling effect on the ants. With increasing walking speed, stride length (Fig. Sometimes, we call things boring simply because they lie outside the box we are currently in.. Fan and his colleagues are already working to develop commercial applications for their technology, which is fairly complex in design, according to Yu. This is also apparent in the analysis of gait index (Fig. Already a subscriber? Food density is low and long distances may have to be covered during foraging, with shady resting places absent or far apart because of sparse vegetation and mostly blue sky. This makes the duty factor a quite useful concept for the present study. Conceptualization: S.E.P., V.L.W., M.W., H.W. Last year, Stanford physicist and nanoscientist Shanhui Fan published a study on radiative cooling in the journal Nature. Delays in homing may have serious consequences, making an excellent navigation ability and fast and efficient locomotion for straight and rapid homing important survival skills. The hairs are about the same size as the suns warming rays, which scatter or bounce off their triangular walls. We further quantified the ant's inter-leg coordination by assigning each video frame an index number and a respective index colour, corresponding to the momentary leg coordination observed in that particular video frame (cf. A striking characteristic of desert ant locomotion appears to be the middle legs performing the fastest swing movements, spending less time in the air than the front and hind legs, and therefore showing the highest duty factor (see Fig. Cataglyphisfortis shows a gradual increase in the number indices over the entire walking speed range; there were statistically significant differences between neighbouring speed bins (one-way ANOVA): <50mms1 and 50 to <150mms1 (***P0.001); 50 to <150mms1 and 150 to <250mms1 (*P0.017); 150 to <250mms1 and 250 to <350mms1 (**P=0.010); 350 to <450mms1 and 450 to <550mms1 (*P=0.025); 450 to <550mms1 and 550 to <650mms1 (*P=0.013). About a year ago, I happened upon this statement about the Monitor in the Harvard Business Review under the charming heading of do things that dont interest you: Many things that end up being meaningful, writes social scientist Joseph Grenny, have come from conference workshops, articles, or online videos that began as a chore and ended with an insight. (B,D) Quantitative analyses according to walking speed class (<50 to >750mms1) for C. bombycina (B; n=71) and C. fortis (D; n=70). For statistical comparisons of circular data, the CircStat toolbox (Berens, 2009) was used. Behaviourally, the ants take advantage of thermal refuges like elevated pebbles or grass blades where available (Wehner and Wehner, 2011) (Fig. This is the reason why the duty factor is often used to characterize the transition from walking to running, especially for bipedal runners (see Discussion). 3B). Our Workshops bring together leading experts and early-career researchers from a range of scientific backgrounds. This is the best thing you can do without electricity. That is, larger individuals had proportionately longer legs, and vice versa. Graham Scott talks to Big Biology about the oxygen cascade in mice living on mountaintops, extreme environments for such small organisms. Most morphological data for C. fortis were kindly provided by S. Sommer and R. Wehner. TCS (Fig. No data were available for the <50mms1 speed class in C. bombycina, and for the 650 to <750mms1 and 750mms1 speed classes in C. fortis. We were able to measure top absolute walking speeds of 855mms1 in C. bombycina, a value that comes close to the maximum running speeds of 1ms1 recorded previously (Wehner, 1983) with different methods. Much of the energy in the visible light that does get absorbed is then converted to longer wavelength infrared light, which is then efficiently radiated away through the hairs. We analysed the footfall patterns of the legs in the PEP, just before lift-off at the end of stance, and in the AEP, just after touch-down at the beginning of stance (Fig. The silver hairs cooling effect works in concert with other adaptations that help the ants beat the heat. The ants adaption resembles cutting-edge, heat-resistant surfaces and may inspire new approaches to such materials. We believe news can and should expand a sense of identity and possibility beyond narrow conventional expectations. To determine lateral velocity (along the transverse axis, perpendicular to longitudinal movement), a regression line was first calculated, running through the petiole images in five consecutive video frames. Only straight and linear running trajectories with regular stride patterns were used for analyses. If you combine these two effects, you have the best combination it will block incoming sunlight and dissipate thermal energy when heated up, Yu adds. The velocity of leg movements rose with increasing walking speed in an almost linear fashion, indicated by swing speed (Fig. Depending on body length, walking speed and ambient temperature, Reynolds numbers for C. bombycina range from about 140 (for an 8mm ant walking at a medium speed of 300mms1 at 45C) to 570 (for an 11mm ant walking at the maximum speed of 840mms1 and a moderate temperature of 30C). Shorter leg lengths are compensated for by high stride frequencies, ranging beyond 40Hz. This website uses cookies to This is due to the fact that swing phases are performed without mechanical load that relates to walking speed. Second, the high synchrony in the leg movements of a tripod should distribute body mass rather evenly across the tripod. Lateral acceleration is the respective change of lateral velocity in a 1ms time interval (see FigsS4 and S5C). Lengths of the alitrunk (fused thorax and first abdominal segment, or propodeum) and leg pairs in C. bombycina (n=87) and C. fortis (n=100) were obtained for morphometric comparison (see Fig. Stride frequency is restricted by muscle contraction and relaxation kinetics (Rubin et al., 2016). But why dont the hairs reflect the ants thermal radiation back into its skin? This is true not only in absolute terms but also explicitly for measurements normalized to body dimensions. Dont yet have access? These Reynolds numbers are typically relevant for small flying insects, such as small Drosophila species. Statistically significant changes in gait representation occurred between all adjacent speed bins except one (see Fig. ameise ants saharan mier schnellste ameisen cataglyphis bombycina pootjes snelste branden ter schnellsten zentimetern flitzt douz derstandard