FYFD

Tag: tongues

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    A Toad’s Sticky Saliva

    Frogs and toads shoot out their tongues to capture and envelop their prey in a fraction of a second. They owe their success in this area to two features: the squishiness of their tongues and the stickiness of their saliva. The super squishy toad tongue deforms to touch as much of the insect as possible. That shape-changing helps deliver the saliva, which is an impressively fast-acting, shear-thinning fluid. Under normal circumstances, the saliva is sticky and about as viscous as honey. But the shear from the tongue’s impact makes the saliva flow like water, spreading across the insect’s body. Then it morphs back into its viscous, sticky self, providing enough adhesive power that the insect can’t escape the toad pulling its tongue back in. (Video credit: Deep Look/KQED; research credit: A. Noel et al.)

  • Honeybee Feeding

    Honeybee Feeding

    Busy bees feed on millions of flowers for each kilogram of honey they produce. To gather nectar, bees use their hairy tongues, which project out of a sheath-like cover. Protraction (i.e., sticking their tongue out) is relatively fast because all the hairs on the tongue initially lie flat. In the nectar, those hairs flare out, creating a miniature forest that traps viscous nectar and drags it back into the bee during retraction.

    Animation of a honeybee feeding, using its hairy tongue.
    Bees feed by projecting their tongues into nectar. Tongue extension is faster because the tongue’s hairs lie flat. During the slower retraction phase, the hairs flare out, trapping nectar and pulling it back into the bee.

    Through modeling and experiments, researchers found that the time it takes a bee to retract its tongue depends on the bee’s overall mass. Smaller bees are slower to the retract their tongues, likely to allow enough time for their shorter tongues to capture enough nectar. With bee populations on the decline, the team’s predictions may help communities select flowers with nectar concentrations that best fit their local bees’ needs. (Image credits: top – J. Szabó, bee eating – B. Wang et al.; research credit: B. Wang et al.; via APS Physics)

  • Sliding Foams

    Sliding Foams

    What happens when a foam interacts with a sliding surface? That’s the question at the heart of this study, which finds three major regimes of foam-surface interaction. On smooth surfaces (Image 1), foams will simply slide against the wall without sticking or deforming. When surface roughness is about as large as the foam’s wall thickness (Image 2), the foam will stick to individual asperities, then slip to the next rough spot as the wall moves. But when the surface roughness is large compared to the foam wall (Image 3), the foam will remain anchored to the surface and all the shear from the wall’s movement goes into deforming the bulk of the foam.

    Researchers thus found they could change foam’s behavior by changing the surface roughness. They also looked at the reverse situation: a surface with fixed roughness — like, say, a human tongue — and how tuning the size of foam bubbles might alter perception and ease of swallowing. That’s what we’re looking at in the last image, where a spoon slides a foam along a surface with roughness similar to the human tongue. (Image and research credit: M. Marchand et al.)