{"363411":{"#nid":"363411","#data":{"type":"news","title":"Slick and slender snake beats short and stubby lizard in sand swimming","body":[{"value":"\u003Cp\u003EFor swimming through sand, a slick and slender snake can perform better than a short and stubby lizard.\u003C\/p\u003E\u003Cp\u003EThat\u2019s one conclusion from a study of the movement patterns of the shovel-nosed snake, a native of the Mojave Desert of the southwest United States. The research shows how the snake uses its slender shape to move smoothly through the sand, and how its slippery skin reduces friction \u2013 both providing locomotive advantages over another sand-swimmer: the sandfish lizard native to the Sahara Desert of northern Africa.\u003C\/p\u003E\u003Cp\u003EThe study provides information that could help explain how evolutionary pressures have affected body shape among sand-dwelling animals. And the work could also be useful in designing search and rescue robots able to move through sand and other granular materials.\u003C\/p\u003E\u003Cp\u003EUsing X-ray technology to watch each creature as it moved through a bed of sand, researchers studied the waves propagating down the bodies of both the snakes and sandfish lizards. Granular resistive force theory, which considers the thrust provided by the body waves and the drag on the animals\u2019 bodies, helped model the locomotion and compare the energy efficiency of the limbless snake against that of the four-legged lizard \u2013 which doesn\u2019t use its legs to swim through the sand.\u003C\/p\u003E\u003Cp\u003E\u201cWe were curious about how this snake moved, and once we observed its movement, how it moved so well in the sand,\u201d said \u003Ca href=\u0022https:\/\/www.physics.gatech.edu\/user\/daniel-goldman\u0022\u003EDan Goldman\u003C\/a\u003E, an associate professor in the \u003Ca href=\u0022http:\/\/www.physics.gatech.edu\/\u0022\u003ESchool of Physics\u003C\/a\u003E at the Georgia Institute of Technology. \u201cOur model reveals how both the snake and the sandfish move as fast as their body shapes permit while using the least amount of energy. We found that the snake\u2019s elongated shape allowed it to beat the sandfish in both speed and energy efficiency.\u201d\u003C\/p\u003E\u003Cp\u003EInformation about the factors enabling the snake to move quickly and efficiently could help the designers of future robotic systems. \u201cKnowing how the snake moves could be useful, for instance, in helping robots go farther on a given amount of battery power,\u201d Goldman said.\u003C\/p\u003E\u003Cp\u003ESupported by the National Science Foundation and the Army Research Office, the research was published online December 18, 2014, in the \u003Cem\u003EJournal of Experimental Biology\u003C\/em\u003E. The study is believed to be the first kinematic investigation of subsurface locomotion in the long and slender shovel-nosed snake, \u003Cem\u003EChionactis occipitalis\u003C\/em\u003E.\u003C\/p\u003E\u003Cp\u003EMeasurements made by former Ph.D. student Sarah Sharpe revealed that the snake propagates traveling waves down its body, from head to tail, creating a body curvature and a number of waves along its body that enhance its movement through the sand. As a consequence of the kinematics, the snake\u2019s body travels mostly in the same \u201ctube\u201d through the sand that is created by the movement of its wedge-shaped head and body.\u003C\/p\u003E\u003Cp\u003EBecause the snake essentially follows its own tracks through the sand, the amount of slip generated by its motion is small, allowing it to move through the sand using less energy than the sandfish (\u003Cem\u003EScincus scincus\u003C\/em\u003E), whose movement pattern generated a larger fluidized region of sand around its body.\u003C\/p\u003E\u003Cp\u003EOverall, the research showed that each animal had optimized its ability to swim through the sand using its specific body plan.\u003C\/p\u003E\u003Cp\u003E\u201cFor each body wave the snake generates, it moves farther than the sandfish does within a single wave of motion of its body,\u201d Goldman noted. \u201cHaving a long and slender body allows the snake to bend its body with greater amplitude while generating more waves on its body, making it a more efficient sand swimmer.\u201d\u003C\/p\u003E\u003Cp\u003EThe snake\u2019s skin is also more slippery than that of the sandfish, further reducing the amount of energy required to move through the sand.\u003C\/p\u003E\u003Cp\u003EScientists had suspected that long and slender animals would have a sand-swimming advantage over creatures with different body shapes. The research showed that the advantage results from a high length-to-width ratio that allows the formation of more waves.\u003C\/p\u003E\u003Cp\u003E\u201cIf you have the right body shape and slick skin, you can get a very low cost of transport,\u201d explained Goldman.\u003C\/p\u003E\u003Cp\u003ETo study the snakes as they moved through sand, Sharpe \u2013 from Georgia Tech\u2019s Interdisciplinary Bioengineering Program \u2013 and undergraduate Robyn Kuckuk, from the Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory University, glued tiny lead markers onto the scales of the snakes. The markers, which fall off when the snakes shed their skin, allowed the researchers to obtain X-ray images of the snakes moving beneath the surface of the sand. Sharpe, now a biomechanical engineer with a research and consulting firm in Phoenix, created detailed videos showing how the snakes moved.\u003C\/p\u003E\u003Cp\u003EAssociate professor Patricio Vela and graduate student Miguel Serrano, both from Georgia Tech\u2019s School of Electrical and Computer Engineering, developed software algorithms that allowed detailed analysis of the wave-forms seen on the X-ray movies as a function of time.\u003C\/p\u003E\u003Cp\u003EStephan Koehler, a research associate in applied physics at Harvard University, applied Resistive Force Theory to obtain data on the snakes\u2019 movement and energy efficiency. Animals swimming in sand can only move if the thrust provided by their bodies exceeds the drag created. The theory predicted that the snakes\u2019 skin would have about half as much friction as that of the sandfish, and that prediction was verified experimentally.\u003C\/p\u003E\u003Cp\u003EJoe Mendelson, director of research at Zoo Atlanta, assisted the research team in obtaining and managing the snakes.\u003C\/p\u003E\u003Cp\u003EUnderstanding how animals move through granular materials like sand could help the designers of robotic systems better understand how to optimize the use of energy, which can be a significant limiting factor in robotics.\u003C\/p\u003E\u003Cp\u003E\u201cThis research is really about how body shape and form affect movement efficiency, and how we can go between experiment and theory to improve our understanding of these issues,\u201d said Goldman. \u201cWhat we are learning could help search and rescue robots maneuver in complex terrain and avoid obstacles.\u201d\u003C\/p\u003E\u003Cp\u003EBeyond the robotics concerns, the work can help scientists understand biological issues, such as how the body plans of desert-dwelling lizards and snakes converge to optimize their ability to move through their environment.\u003C\/p\u003E\u003Cp\u003E\u201cThese granular swimming systems turn out to be quite useful for understanding fundamental questions about evolutionary biology, biomechanics and energetics because they are simple to analyze and they can describe a good number of systems,\u201d Goldman added.\u003C\/p\u003E\u003Cp\u003EThis material is based upon work supported by the National Science Foundation (NSF) under grant number PHY-0749991 and PHY-1150760, and by the Army Research Office (ARO) under grant number W911NF-11-1-0514. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation or the Army Research Office.\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003ECITATION\u003C\/strong\u003E: Sarah Sharpe, et al., \u201cLocomotor benefits of being a slender and slick sand swimmer,\u201d (Journal of Experimental Biology, 2014). \u003Ca href=\u0022http:\/\/www.dx.doi.org\/10.1242\/jeb.108357\u0022 title=\u0022http:\/\/www.dx.doi.org\/10.1242\/jeb.108357\u0022\u003Ehttp:\/\/www.dx.doi.org\/10.1242\/jeb.108357\u003C\/a\u003E\u003Cbr \/\u003E\u003Cbr \/\u003E\u003Cstrong\u003EResearch News\u003C\/strong\u003E\u003Cbr \/\u003E\u003Cstrong\u003EGeorgia Institute of Technology\u003C\/strong\u003E\u003Cbr \/\u003E\u003Cstrong\u003E177 North Avenue\u003C\/strong\u003E\u003Cbr \/\u003E\u003Cstrong\u003EAtlanta, Georgia\u0026nbsp; 30332-0181\u003C\/strong\u003E\u003Cbr \/\u003E\u003Cbr \/\u003E\u003Cstrong\u003EMedia Relations Contacts\u003C\/strong\u003E: John Toon (404-894-6986) (\u003Ca href=\u0022mailto:jtoon@gatech.edu\u0022\u003Ejtoon@gatech.edu\u003C\/a\u003E) or Brett Israel (404-385-1933) (\u003Ca href=\u0022mailto:brett.israel@comm.gatech.edu\u0022\u003Ebrett.israel@comm.gatech.edu\u003C\/a\u003E).\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003EWriter\u003C\/strong\u003E: John Toon\u003C\/p\u003E","summary":null,"format":"limited_html"}],"field_subtitle":"","field_summary":[{"value":"\u003Cp\u003EFor swimming through sand, a slick and slender snake can perform better than a short and stubby lizard. That\u2019s one conclusion from a study of the movement patterns of the shovel-nosed snake, a native of the Mojave Desert of the southwest United States.\u003C\/p\u003E","format":"limited_html"}],"field_summary_sentence":[{"value":"For swimming through sand, a slick and slender snake can perform better than a short and stubby lizard."}],"uid":"27303","created_gmt":"2015-01-12 16:11:04","changed_gmt":"2016-10-08 03:17:50","author":"John Toon","boilerplate_text":"","field_publication":"","field_article_url":"","dateline":{"date":"2015-01-12T00:00:00-05:00","iso_date":"2015-01-12T00:00:00-05:00","tz":"America\/New_York"},"extras":[],"hg_media":{"363351":{"id":"363351","type":"image","title":"Shovel-nosed snake","body":null,"created":"1449245793","gmt_created":"2015-12-04 16:16:33","changed":"1475895098","gmt_changed":"2016-10-08 02:51:38","alt":"Shovel-nosed snake","file":{"fid":"201612","name":"shovelnosed2.jpg","image_path":"\/sites\/default\/files\/images\/shovelnosed2_0.jpg","image_full_path":"http:\/\/www.tlwarc.hg.gatech.edu\/\/sites\/default\/files\/images\/shovelnosed2_0.jpg","mime":"image\/jpeg","size":340291,"path_740":"http:\/\/www.tlwarc.hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/shovelnosed2_0.jpg?itok=tzUMoV9k"}},"363371":{"id":"363371","type":"image","title":"Shovel-nosed snake2","body":null,"created":"1449245793","gmt_created":"2015-12-04 16:16:33","changed":"1475895098","gmt_changed":"2016-10-08 02:51:38","alt":"Shovel-nosed snake2","file":{"fid":"201613","name":"shovelnosed_0459.jpg","image_path":"\/sites\/default\/files\/images\/shovelnosed_0459_0.jpg","image_full_path":"http:\/\/www.tlwarc.hg.gatech.edu\/\/sites\/default\/files\/images\/shovelnosed_0459_0.jpg","mime":"image\/jpeg","size":1929758,"path_740":"http:\/\/www.tlwarc.hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/shovelnosed_0459_0.jpg?itok=oYxVMAL1"}},"363381":{"id":"363381","type":"image","title":"Shovel-nosed snake3","body":null,"created":"1449245793","gmt_created":"2015-12-04 16:16:33","changed":"1475895098","gmt_changed":"2016-10-08 02:51:38","alt":"Shovel-nosed snake3","file":{"fid":"201614","name":"shovelnosed_9713.jpg","image_path":"\/sites\/default\/files\/images\/shovelnosed_9713_0.jpg","image_full_path":"http:\/\/www.tlwarc.hg.gatech.edu\/\/sites\/default\/files\/images\/shovelnosed_9713_0.jpg","mime":"image\/jpeg","size":2818843,"path_740":"http:\/\/www.tlwarc.hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/shovelnosed_9713_0.jpg?itok=X8m8adqr"}},"363391":{"id":"363391","type":"image","title":"Shovel-nosed snake4","body":null,"created":"1449245793","gmt_created":"2015-12-04 16:16:33","changed":"1475895098","gmt_changed":"2016-10-08 02:51:38","alt":"Shovel-nosed snake4","file":{"fid":"201615","name":"shovelnosed7306.jpg","image_path":"\/sites\/default\/files\/images\/shovelnosed7306_0.jpg","image_full_path":"http:\/\/www.tlwarc.hg.gatech.edu\/\/sites\/default\/files\/images\/shovelnosed7306_0.jpg","mime":"image\/jpeg","size":1558860,"path_740":"http:\/\/www.tlwarc.hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/shovelnosed7306_0.jpg?itok=mzI0339V"}}},"media_ids":["363351","363371","363381","363391"],"groups":[{"id":"1188","name":"Research Horizons"}],"categories":[{"id":"146","name":"Life Sciences and Biology"},{"id":"135","name":"Research"}],"keywords":[{"id":"47881","name":"Dan Goldman"},{"id":"169701","name":"sand swimming"},{"id":"169581","name":"sandfish"},{"id":"169702","name":"shovel-nosed snake"},{"id":"169001","name":"Snake"}],"core_research_areas":[{"id":"39441","name":"Bioengineering and Bioscience"},{"id":"39521","name":"Robotics"}],"news_room_topics":[{"id":"71911","name":"Earth and Environment"},{"id":"71881","name":"Science and Technology"}],"event_categories":[],"invited_audience":[],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[{"value":"\u003Cp\u003EJohn Toon\u003C\/p\u003E\u003Cp\u003EResearch News\u003C\/p\u003E\u003Cp\u003E\u003Ca href=\u0022mailto:jtoon@gatech.edu\u0022\u003Ejtoon@gatech.edu\u003C\/a\u003E\u003C\/p\u003E\u003Cp\u003E(404) 894-6986\u003C\/p\u003E","format":"limited_html"}],"email":["jtoon@gatech.edu"],"slides":[],"orientation":[],"userdata":""}}}