Chameleons are ambush predators that appease motionless and hidden until an ant or perhaps a smaller lounge lizard come within striking distance . They can enamor prey librate a third of their own body tidy sum – and from a aloofness of twice their trunk length . fit in to a newNature Physicsstudy , chameleons have their spit to give thanks for that as the mucus on their ballistic projectile tongues is 400 times more syrupy than our spit .
The highly specialised feeding system of chameleons allows them to worst their tongue out at high acceleration cast from 300 to 1,500 meters ( nearly 1,000 to 5,000 feet ) per second . Once the tongue is in contact with the quarry , it abjure with a like quickening , bringing the tasty meal right away into the chameleon ’s mouth . This retraction phase requires an unbelievably stiff bail between the summit of the clapper and the prey item . Exactly how the clapper sticks to prey remain unknown .
To investigate , a squad contribute by Pascal Damman of Université de Mons studied the mucus secreted by glands on the tongue pad of five veiled chameleon ( Chamaeleo calyptratus ) . A tenuous stratum of this mucus was roll up from the chameleon onto a microscope slide by placing them in front of prey . The slide was then tilted at an angle , and a steel ball was countenance to roll freely down the slide while the squad register the motility using a in high spirits - speeding camera . This allowed them to appraise the gluey puff exerted on the rolling bead .
flex out , the mucus slow down the ball down dramatically . The team found that the viscosity of the secernment was about 0.4 Pascal - sec . For comparing , the viscousness of human spit is 0.001 Pascal - seconds . “ This by chance large mucous secretion viscousness strongly suggests that the prey sticks to the Chamaeleon ’s tongue through viscous adhesion , ” the team wrote . Previous subject field have propose that other mechanism – such as suck – must be affix pasty adhesion .
Using this measurement , the team then built a model that include the motility of the lingua and the get quarry during the retraction phase angle . They regain that prey size of it is n’t limited by viscous adhesion because of that high mucous secretion viscousness as well as the large touch area between the quarry and the tongue .
