Chameleons are naturally equipped with vicious tongues that make them efficient predators that feed on bugs, birds, mice, and even their own kind. A new study reveals just how potent their sticky weapons are: the chameleon's sticky mucus at the tip of their tongue is 400 times thicker than human saliva enabling them to snag a large prey.
To catch a prey, chameleons unfurl their tongues toward their target at remarkable jet speed. But the precise high-speed attack is only the first step. To enjoy their meal, they must have to successfully bring the unlucky prey back to its mouth. However, the small reptilian creatures do not wrap their prey using their tongue. This could only mean that their catch must stick well to their powerful tongues.
Published in Nature Physics, physicist Pascal Damman of the University of Mons in Belgium and his colleagues reveal that the reptiles produce a highly thick mucus 400 times sticker than human saliva at the tip of their tongues.
"What we show is that the simplest explanation works. The factor that limits the size of the prey is probably the size of the mouth of the chameleon," Damman said as per Christian Science Monitor.
The saliva's viscous adhesive bond strengthens when the pull of the tongue on the insect is stronger and faster. When the tongue relaxes, the bond loosens and eventually fades away which enables to chameleon to eat the prey without chewing off its tongue.
To measure just how potent a chameleon's saliva is, the researchers collected a saliva sample from Chamaeleo calyptratus. They did this by allowing the chameleon to shoot its uber-fast tongue out to catch a small cricket placed behind a glass pane. After hitting the glass, the tongue left a smear of saliva sample which was then collected for study.
The next step was to calculate the spit's viscosity by rolling a bead on tilted plate doused with chameleon's saliva and measure how it slowed the bead's downward movement. The scientists later found out that the chameleon's saliva was as thick as honey which keeps the prey stuck even as the tongue rolls back at an acceleration of 40Gs, The Verge reported.
The discovery caught the scientists by surprise. They further noted that same saliva properties may also be found in other reptiles such as frogs, salamanders, and toads that all use their sticky tongues at incredibly high speed to catch their meals.
