{"586735":{"#nid":"586735","#data":{"type":"news","title":"Reversible Saliva Allows Frogs to Hang on to Next Meal","body":[{"value":"\u003Cp\u003EA frog uses its whip-like tongue to snag its prey faster than a human can blink, hitting it with a force five times greater than gravity. How does it hang onto its meal as the food rockets back into its mouth?\u003C\/p\u003E\r\n\r\n\u003Cp\u003EA new Georgia Institute of Technology study says the tongue\u0026rsquo;s stickiness is caused by a unique reversible saliva in combination with a super soft tongue. A frog\u0026rsquo;s saliva is thick and sticky during prey capture, then turns thin and watery as prey is removed inside the mouth. The tongue, which was found to be as soft as brain tissue and 10 times softer than a human\u0026rsquo;s tongue, stretches and stores energy much like a spring. This combination of spit and softness is so effective that it provides the tongue 50 times greater work of adhesion than synthetic polymer materials such as sticky-hand toys.\u003C\/p\u003E\r\n\r\n\u003Cp\u003EThe Georgia Tech researchers filmed frogs eating crickets in super-slow motion to better understand the physics of the tongue. They also collected saliva samples and poked the tissue to measure softness.\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026ldquo;\u003Ca href=\u0022https:\/\/www.youtube.com\/watch?v=IubFs-PtzhM\u0022\u003EThe tongue acts like a bungee cord once it latches onto its prey\u003C\/a\u003E,\u0026rdquo; said Alexis Noel, a Georgia Tech mechanical engineering Ph.D. student who led the study. \u0026ldquo;It deforms itself as it pulls back toward the mouth, continually storing the intense applied forces in its stretchy tissue and dissipating them in its internal damping.\u0026rdquo;\u003C\/p\u003E\r\n\r\n\u003Cp\u003EThis tissue damping, Noel said, is much like a car\u0026rsquo;s shock absorbers. The tongue\u0026rsquo;s softness also allows it to change shape during contact and immediately afterward while retracting.\u003C\/p\u003E\r\n\r\n\u003Cp\u003EThe other vital component of the capturing process is the frog\u0026rsquo;s versatile saliva.\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026ldquo;There are actually three phases,\u0026rdquo; Noel said. \u0026ldquo;When the tongue first hits the insect, the saliva is almost like water and fills all the bug\u0026rsquo;s crevices. Then, when the tongue snaps back, the saliva changes and becomes more viscous \u0026mdash; thicker than honey, actually \u0026mdash; gripping the insect for the ride back. \u0026nbsp;The saliva turns watery again when the insect is sheared off inside the mouth.\u0026rdquo;\u003C\/p\u003E\r\n\r\n\u003Cp\u003EUnlike water and honey, frog saliva can change its viscosity with shear rate, much like paint. Paint spreads easily when applied, but stays firmly on the wall once the brush is removed.\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026ldquo;For frogs, saliva seeps easily when it hits the insect, then thickens up during retraction,\u0026rdquo; she said.\u003C\/p\u003E\r\n\r\n\u003Cp\u003EThis spit switch can\u0026rsquo;t be seen in the \u003Ca href=\u0022https:\/\/www.youtube.com\/watch?v=nOmYONEkDG8\u0026amp;list=PLme0Eox75uXb1L5FBPmkN3K6oByAD1UwI\u0022\u003Eslow-mo videos\u003C\/a\u003E. To identify the shear rate when viscosity drops, Noel collected saliva from 18 frogs and placed samples in a rheometer, a highly sensitive device for measuring properties of fluids.\u003C\/p\u003E\r\n\r\n\u003Cp\u003EDavid Hu, a professor in the George W. Woodruff School of Mechanical Engineering, is Noel\u0026rsquo;s advisor who has also studied how \u003Ca href=\u0022http:\/\/www.news.gatech.edu\/2012\/06\/04\/mosquitoes-fly-rain-thanks-low-mass\u0022\u003Emosquitos fly in the rain\u003C\/a\u003E\u003Ca href=\u0022http:\/\/www.news.gatech.edu\/2010\/12\/16\/wet-mammals-shake-dry-milliseconds\u0022\u003E, how dogs shake off water\u003C\/a\u003E and \u003Ca href=\u0022http:\/\/www.news.gatech.edu\/2015\/02\/25\/easy-eyes-how-eyelash-length-keeps-your-eyes-healthy\u0022\u003Ewhy eyelashes need to be an ideal length\u003C\/a\u003E. He says the frog study could help engineers design reversible adhesives at high speed.\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026ldquo;Most adhesives that have been created are stiff, especially tape,\u0026rdquo; said Hu, who is also a faculty member in the School of Biological Sciences. \u0026ldquo;Frog tongues can attach and reattach with soft, special properties that are extremely stickier than typical materials. Perhaps this technology could be used for new Band-Aids. Or it could be used to create new materials in soft manufacturing.\u0026rdquo;\u003C\/p\u003E\r\n\r\n\u003Cp\u003EThe Georgia Tech team worked with Mark Mandica, the leading herpetologist at the \u003Ca href=\u0022http:\/\/amphibianfoundation.org\/\u0022\u003EAmphibian Foundation\u003C\/a\u003E in Atlanta. The foundation brings together top researchers in the field of amphibian biology, conservation, and applied science to address the causes of global amphibian declines. Current research estimates that 38 percent of the world\u0026rsquo;s amphibian populations are in decline or already extinct.\u003C\/p\u003E\r\n\r\n\u003Cp\u003EThe study, \u0026ldquo;\u003Ca href=\u0022http:\/\/rsif.royalsocietypublishing.org\/lookup\/doi\/10.1098\/rsif.2016.0764\u0022\u003EFrogs use a viscoelastic tongue and non-Newtonian saliva to catch prey\u003C\/a\u003E,\u0026rdquo; is published in the Journal of the Royal Society Interface.\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cem\u003E\u003Ca href=\u0022http:\/\/https:\/\/www.dropbox.com\/sh\/4bqwyc42v3uswal\/AAA78HvpIEg3bfS2vAd2fDrpa?dl=0\u0022\u003EMore video and images are available for media. \u003C\/a\u003E\u003Cbr \/\u003E\r\n\u003Cbr \/\u003E\r\nThe project is partially supported by National Science Foundation (NSF) Graduate Research Fellowship (DGE-1148903) and NSF career award PHY-1255127. Any opinions, findings and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the sponsors. \u003C\/em\u003E\u003C\/p\u003E\r\n","summary":null,"format":"limited_html"}],"field_subtitle":[{"value":"Spit switch and tongue\u2019s softness keep frog tongues sticky"}],"field_summary":[{"value":"\u003Cp\u003EA new Georgia Tech study says a frog tongue\u0026rsquo;s stickiness is caused by a unique reversible saliva in combination with a super soft tongue. A frog\u0026rsquo;s saliva is thick and sticky during prey capture, then turns thin and watery as prey is removed inside the mouth. The tongue, which was found to be as soft as brain tissue and 10 times softer than a human\u0026rsquo;s tongue, stretches and stores energy much like a spring.\u003C\/p\u003E\r\n","format":"limited_html"}],"field_summary_sentence":[{"value":"A frog\u0027s saliva changes three times in milliseconds as it snares food with its tongue."}],"uid":"27560","created_gmt":"2017-01-31 21:57:03","changed_gmt":"2017-01-31 23:59:29","author":"Jason Maderer","boilerplate_text":"","field_publication":"","field_article_url":"","dateline":{"date":"2017-01-31T00:00:00-05:00","iso_date":"2017-01-31T00:00:00-05:00","tz":"America\/New_York"},"extras":[],"hg_media":{"586733":{"id":"586733","type":"image","title":"Northern leopard frog ","body":null,"created":"1485898894","gmt_created":"2017-01-31 21:41:34","changed":"1485898894","gmt_changed":"2017-01-31 21:41:34","alt":"Frog eating","file":{"fid":"223599","name":"Frog.jpg","image_path":"\/sites\/default\/files\/images\/Frog.jpg","image_full_path":"http:\/\/hg.gatech.edu\/\/sites\/default\/files\/images\/Frog.jpg","mime":"image\/jpeg","size":654994,"path_740":"http:\/\/hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/Frog.jpg?itok=nhWPAMXZ"}},"586732":{"id":"586732","type":"image","title":"Alexis Noel","body":null,"created":"1485898724","gmt_created":"2017-01-31 21:38:44","changed":"1485898724","gmt_changed":"2017-01-31 21:38:44","alt":"Alexis Noel","file":{"fid":"223598","name":"ALEXIS NOEL.jpg","image_path":"\/sites\/default\/files\/images\/ALEXIS%20NOEL.jpg","image_full_path":"http:\/\/hg.gatech.edu\/\/sites\/default\/files\/images\/ALEXIS%20NOEL.jpg","mime":"image\/jpeg","size":590277,"path_740":"http:\/\/hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/ALEXIS%20NOEL.jpg?itok=00ky1NlQ"}},"382241":{"id":"382241","type":"image","title":"David Hu","body":null,"created":"1449246231","gmt_created":"2015-12-04 16:23:51","changed":"1493396247","gmt_changed":"2017-04-28 16:17:27","alt":"Daivd Hu","file":{"fid":"75309","name":"hu.jpg","image_path":"\/sites\/default\/files\/images\/hu.jpg","image_full_path":"http:\/\/hg.gatech.edu\/\/sites\/default\/files\/images\/hu.jpg","mime":"image\/jpeg","size":24895,"path_740":"http:\/\/hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/hu.jpg?itok=3IFHegGR"}}},"media_ids":["586733","586732","382241"],"related_links":[{"url":"https:\/\/www.youtube.com\/watch?v=nOmYONEkDG8\u0026list=PLme0Eox75uXb1L5FBPmkN3K6oByAD1UwI","title":"See More Video"},{"url":"http:\/\/rsif.royalsocietypublishing.org\/lookup\/doi\/10.1098\/rsif.2016.0764","title":"Read the Study"}],"groups":[{"id":"1214","name":"News Room"},{"id":"108731","name":"School of Mechanical Engineering"},{"id":"1275","name":"School of Biological Sciences"},{"id":"1183","name":"Home"}],"categories":[],"keywords":[{"id":"173354","name":"Frog"},{"id":"173355","name":"Frog tongue"},{"id":"297","name":"David Hu"}],"core_research_areas":[{"id":"39471","name":"Materials"}],"news_room_topics":[{"id":"71881","name":"Science and Technology"}],"event_categories":[],"invited_audience":[],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[{"value":"\u003Cp\u003EJason Maderer\u003Cbr \/\u003E\r\nNational Media Relations\u003Cbr \/\u003E\r\nmaderer@gatech.edu\u003Cbr \/\u003E\r\n404-660-2926\u003C\/p\u003E\r\n","format":"limited_html"}],"email":["maderer@gatech.edu"],"slides":[],"orientation":[],"userdata":""}}}