{"54677":{"#nid":"54677","#data":{"type":"news","title":"Study Shows How Sea Turtle Hatchlings Move Quickly on Sand","body":[{"value":"\u003Cp\u003ELife can be scary for endangered loggerhead sea turtles immediately after they hatch. After climbing out of their underground nest, the baby turtles must quickly traverse a variety of terrains for several hundred feet to reach the ocean. \u003C\/p\u003E\n\u003Cp\u003EWhile these turtles\u2019 limbs are adapted for a life at sea, their flippers enable excellent mobility over dune grass, rigid obstacles and sand of varying compaction and moisture content. A new field study conducted by researchers at the Georgia Institute of Technology is the first to show how these hatchlings use their limbs to move quickly on loose sand and hard ground to reach the ocean. This research may help engineers build robots that can travel across complex environments.\n\u003C\/p\u003E\n\u003Cp\u003E\u201cLocomotion on sand is challenging because sand surfaces can flow during limb interaction and slipping can result, causing both instability and decreased locomotor performance, but these turtles are able to adapt,\u201d said Daniel Goldman, an assistant professor in the Georgia Tech School of Physics. \u201cOn hard-packed sand at the water\u2019s edge, these turtles push forward by digging a claw on their flipper into the ground so that they don\u2019t slip, and on loose sand they advance by pushing off against a solid region of sand that forms behind their flippers.\u201d\n\u003C\/p\u003E\n\u003Cp\u003EDetails of the study were published online on February 10, 2010 in the journal \u003Cem\u003EBiology Letters\u003C\/em\u003E. This research was supported by the Burroughs Wellcome Fund, National Science Foundation, and the Army Research Laboratory.\n\u003C\/p\u003E\n\u003Cp\u003E\u003Cstrong\u003E\u003Cem\u003EClick \u003Ca href=\u0022http:\/\/gtresearchnews.gatech.edu\/wp-content\/uploads\/2010\/02\/turtleVideoS1.mov\u0022\u003E here\u003C\/a\u003E to watch a video of a loggerhead sea turtle on the beach running from its nest to the water.\u003C\/em\u003E\u003C\/strong\u003E\n\u003C\/p\u003E\n\u003Cp\u003EIn collaboration with the Georgia Sea Turtle Center, biology graduate student Nicole Mazouchova studied the movement of sea turtle hatchlings of the species \u003Cem\u003ECaretta caretta \u003C\/em\u003Eat Jekyll Island on the coast of Georgia. She and research technician Andrei Savu worked from a mobile laboratory that contained a nearly three-foot-long trackway filled with dry Jekyll Island sand. \n\u003C\/p\u003E\n\u003Cp\u003EThe trackway contained tiny holes in the bottom through which air could be blown. The air pulses elevated the granules and caused them to settle into a loosely packed solid state, allowing the researchers to closely control the density of the sand.\u003C\/p\u003E\n\u003Cp\u003EIn addition to challenging hatchlings to traverse loosely packed sand in the trackway, the researchers also studied the turtles\u2019 movement on hard surfaces -- a sandpaper-covered board placed on top of the sand. Two high-speed cameras recorded the movements of the hatchlings along the trackway, and showed how the turtles altered their locomotion to move on different surfaces.\n\u003C\/p\u003E\n\u003Cp\u003E\u201cWe assumed that the turtles would perform best on rigid ground because it would not give way under their flippers, but our experiments showed that while the turtles\u2019 average speed on sand was reduced by 28 percent relative to hard ground, their maximal speeds were the same for both surfaces,\u201d noted Goldman.\n\u003C\/p\u003E\n\u003Cp\u003E\u003Cstrong\u003E\u003Cem\u003EClick \u003Ca href=\u0022http:\/\/gtresearchnews.gatech.edu\/wp-content\/uploads\/2010\/02\/turtleVideoS2.mov\u0022\u003E here\u003C\/a\u003E to watch a video showing how a loggerhead sea turtle hatchling moves on granular media.\u003C\/em\u003E\u003C\/strong\u003E\n\u003C\/p\u003E\n\u003Cp\u003EThe researchers\u2019 investigations showed that on the rigid sandpaper surface, the turtles anchored a claw located on their wrists into the sandpaper and propelled themselves forward. During the thrusting process, one of the turtle\u2019s shoulders rotated toward its body and its wrist did not bend, keeping the limb fully extended. \n\u003C\/p\u003E\n\u003Cp\u003EIn contrast, on loosely packed sand, pressure from the thin edge of one of the turtle\u2019s flippers caused the limb to penetrate into the sand. The turtle\u2019s shoulder then rotated as the flipper penetrated until the flipper was perpendicular to the surface and the turtle\u2019s body lifted from the surface. \u003C\/p\u003E\n\u003Cp\u003E\u201cThe turtles dug into the loosely packed sand, lifted their bellies off the ground, lurched forward, stopped, and did it again,\u201d explained Goldman. \n\u003C\/p\u003E\n\u003Cp\u003ETo extend their biological observations, Goldman and physics graduate student Nick Gravish designed an artificial flipper system in the laboratory. The flipper consisted of a thin aluminum plate that was inserted into and dragged along the trackway filled with Jekyll Island sand. Calibrated strain gauges mounted on the flipper provided force measurements during the dragging procedure. \n\u003C\/p\u003E\n\u003Cp\u003E\u201cOur model revealed that a major challenge for rapid locomotion of hatchling sea turtles on sand is the balance between high speed, which requires large inertial forces, and the potential for failure through fluidization of the sand,\u201d explained Goldman. \u201cWe believe that the turtles modulate the amount of force they use to push into the sand so that it remains below the force required for the ground to break apart and become fluidlike.\u201d\n\u003C\/p\u003E\n\u003Cp\u003EGoldman and his team plan to conduct further field studies and laboratory experiments to determine if and how the turtles control their limb movements on granular media to avoid sand fluidization. They are also developing robots that move along granular media like the sea turtle hatchings. \n\u003C\/p\u003E\n\u003Cp\u003E\u201cThese research results are valuable for roboticists who want to know the minimum number of appendage features necessary to move effectively on land and whether they can just design a robot with a flat mitt and a claw like these turtles have,\u201d noted Goldman.\n\u003C\/p\u003E\n\u003Cp\u003E\u003Cem\u003EThis material is based on work supported by the Burroughs Wellcome Fund Career Award at the Scientific Interface. Work related to physics was supported by the Army Research Laboratory (ARL) MAST CTA under Cooperative Agreement Number W911NF-08-2-0004 and the National Science Foundation (NSF) under Award Number CMMI-0825480. Any opinions, views, findings, conclusions or recommendations expressed in this document are those of the researcher and should not be interpreted as representing the official policies, either expressed or implied, of ARL, NSF, or the U.S. Government.\u003C\/em\u003E\n\u003C\/p\u003E\n\u003Cp\u003E\u003Cstrong\u003EResearch News \u0026amp; Publications Office\u003Cbr \/\u003E\nGeorgia Institute of Technology\u003Cbr \/\u003E\n75 Fifth Street, N.W., Suite 314\u003Cbr \/\u003E\nAtlanta, Georgia  30308  USA\n\u003C\/strong\u003E\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003E\n\u003C\/strong\u003E\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003EMedia Relations Contacts:\u003C\/strong\u003E Abby Vogel (404-385-3364; \u003Ca href=\u0022mailto:avogel@gatech.edu\u0022\u003Eavogel@gatech.edu\u003C\/a\u003E) or John Toon (404-894-6986; \u003Ca href=\u0022mailto:jtoon@gatech.edu\u0022\u003Ejtoon@gatech.edu\u003C\/a\u003E)\n\u003C\/p\u003E\n\u003Cp\u003E\u003Cstrong\u003ETechnical Contact:\u003C\/strong\u003E Daniel Goldman (404-894-0993; \u003Ca href=\u0022mailto:daniel.goldman@physics.gatech.edu\u0022\u003Edaniel.goldman@physics.gatech.edu\u003C\/a\u003E)\n\u003C\/p\u003E\n\u003Cp\u003E\u003Cstrong\u003EWriter:\u003C\/strong\u003E Abby Vogel\u003C\/p\u003E","summary":null,"format":"limited_html"}],"field_subtitle":"","field_summary":[{"value":"\u003Cp\u003EGeorgia Tech researchers conducted the first field study showing how endangered loggerhead sea turtle hatchlings use their limbs to move quickly on a variety of terrains to reach the ocean.\u003C\/p\u003E","format":"limited_html"}],"field_summary_sentence":[{"value":"Study shows how sea turtle hatchlings use their limbs to move qu"}],"uid":"27206","created_gmt":"2010-02-24 01:00:00","changed_gmt":"2022-05-26 17:09:36","author":"Abby Vogel Robinson","boilerplate_text":"","field_publication":"","field_article_url":"","dateline":{"date":"2010-02-25T00:00:00-05:00","iso_date":"2010-02-25T00:00:00-05:00","tz":"America\/New_York"},"extras":[],"hg_media":{"54678":{"id":"54678","type":"image","title":"loggerhead sea turtle hatchling","body":null,"created":"1449175459","gmt_created":"2015-12-03 20:44:19","changed":"1475894481","gmt_changed":"2016-10-08 02:41:21","alt":"loggerhead sea turtle hatchling","file":{"fid":"172613","name":"tna57459.jpg","image_path":"\/sites\/default\/files\/images\/tna57459_0.jpg","image_full_path":"http:\/\/tlwarc.hg.gatech.edu\/\/sites\/default\/files\/images\/tna57459_0.jpg","mime":"image\/jpeg","size":1005238,"path_740":"http:\/\/tlwarc.hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/tna57459_0.jpg?itok=xBwvaV4R"}},"54679":{"id":"54679","type":"image","title":"sea turtle hatchling locomotion","body":null,"created":"1449175459","gmt_created":"2015-12-03 20:44:19","changed":"1475894481","gmt_changed":"2016-10-08 02:41:21","alt":"sea turtle hatchling locomotion","file":{"fid":"172614","name":"tgm57459.jpg","image_path":"\/sites\/default\/files\/images\/tgm57459_0.jpg","image_full_path":"http:\/\/tlwarc.hg.gatech.edu\/\/sites\/default\/files\/images\/tgm57459_0.jpg","mime":"image\/jpeg","size":149048,"path_740":"http:\/\/tlwarc.hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/tgm57459_0.jpg?itok=DSNU5ZT_"}},"54680":{"id":"54680","type":"image","title":"loggerhead sea turtle","body":null,"created":"1449175459","gmt_created":"2015-12-03 20:44:19","changed":"1475894481","gmt_changed":"2016-10-08 02:41:21","alt":"loggerhead sea turtle","file":{"fid":"172615","name":"tms57459.jpg","image_path":"\/sites\/default\/files\/images\/tms57459_0.jpg","image_full_path":"http:\/\/tlwarc.hg.gatech.edu\/\/sites\/default\/files\/images\/tms57459_0.jpg","mime":"image\/jpeg","size":300314,"path_740":"http:\/\/tlwarc.hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/tms57459_0.jpg?itok=CUjLETDA"}}},"media_ids":["54678","54679","54680"],"related_links":[{"url":"http:\/\/dx.doi.org\/10.1098\/rsbl.2009.1041","title":"Biology Letters paper"},{"url":"http:\/\/www.physics.gatech.edu\/research\/goldman\/","title":"Daniel Goldman"},{"url":"http:\/\/www.physics.gatech.edu\/","title":"Georgia Tech School of Physics"}],"groups":[{"id":"1188","name":"Research Horizons"}],"categories":[{"id":"154","name":"Environment"},{"id":"135","name":"Research"},{"id":"150","name":"Physics and Physical Sciences"},{"id":"152","name":"Robotics"}],"keywords":[{"id":"8856","name":"hatchling"},{"id":"377","name":"locomotion"},{"id":"960","name":"physics"},{"id":"169242","name":"sand"},{"id":"169396","name":"sea"},{"id":"8855","name":"turtle"}],"core_research_areas":[],"news_room_topics":[],"event_categories":[],"invited_audience":[],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[{"value":"\u003Cp\u003EAbby Vogel - Research News and Publications\u003C\/p\u003E","format":"limited_html"}],"email":["avogel@gatech.edu"],"slides":[],"orientation":[],"userdata":""}}}