It may not have particularly elegant table manners , but despite manducate with its mouth open , the surprising sophistication display by the ocellate river stingray in the video below has left scientists with their jaw agape .
Until now , it had been call up that chew as a form of food processing was execute exclusively by mammals , yet the find thatstingraysalso hire in mastication represents a whole new boiler of fish for evolutionary science .
According to a paper bring out this week in theProceedings of the Royal Society B , chewing – which the authors qualify as “ shearing jaw motions and high up - crowned molars ” – is thought to have allowed the dietetic diversification of mammals , which in turn facilitated the phylogenesis of increasingly complex cognitive and physiologic capacities .
However , given that fish lack thecomplex dental apparatusrequired for jaw , marine biologists had always assumed that they were ineffectual to chow down on their food in the same way .
In venom of this , stingrays are known to track down complex quarry specie such as insects with tough exoskeleton , leading the researchers to enquire how the pancake - mold creatures process their food for thought before digesting it . To find out , they placed four ray belong to the speciesPotamotrygon motoroin a glass - bottomed tank , and used gamey - speed video cameras to film their oral cavity from below as they course on dragonfly larvae .
The researchers discovered that , despite lacking theintricate molars of mammals , thestingraysdid indeed jaw their food before swallowing it , with “ complex , asymmetric jaw motions ” allow them to compress and fleece their prey . Interestingly , the study generator note that the stingrays ’ mouths are used exclusively for this role , and are not deployed as a substance of catch fair game in the first place . rather , this is achieved by “ rapid uplift of the pectoral fins , ” which breastfeed fair game beneath the ray ’s body .
free-base on this finding , the study author propose that the power to apply their Phoebe to capture solid food is what allowed the rays to develop this jaw behavior , as it freed up their mouths for this lonesome purpose , result in the development of “ a extremely kinetic feeding setup . ” This , in turn , enable stingrays to eat on a wide variety of food , thereby help them thrive in a reach of devil dog and freshwater home ground .
