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  • This cricket is about to be dinner.

  • New research reveals what makes a frog's tongue

  • such a formidable weapon.

  • This is Scientific American. I'm Lydia Chain.

  • Since the entire attack takes less

  • than a tenth of a second

  • the researchers set up high-speed

  • cameras to capture the action.

  • "Literally in the blink of an eye, the insect is gone

  • and it's only when we look at it in

  • slow-motion can we really see how the

  • tongue is unfurling from the mouth and

  • impacting the insect.

  • That's Alexis Noel at Georgia Tech.

  • Noel and her colleagues studied frog tongues

  • and the fluid mechanics of their spit

  • to understand how frogs slurp up their prey.

  • First, Noel studied the physical properties of the tongue.

  • It was so soft, Noel had to design

  • special equipment to get an accurate

  • softness measurement.

  • "It's even softer than brain tissue.

  • Even softer than a marshmallow."

  • That soft tongue comes in handy.

  • Prey sinks deep into the tongue's surface,

  • increasing contact for a good grip.

  • The softness also absorbs force

  • like a bungee cord so the frog can reel in

  • a cricket rather than giving it a yank

  • that might cause separation.

  • But it's the saliva that temporarily

  • glues the bug to a frog's tongue.

  • Frog tongues are like spit-saturated sponges

  • since their salivary glands

  • are inside the tongue.

  • Noel and her colleagues analyzed the

  • fluid properties of this saliva.

  • "So I scraped about 17 or 18 frog tongues."

  • Those spit samples revealed frog saliva is

  • a shear thinning fluid.

  • The saliva starts out viscous and sticky,

  • but when force is applied, it liquefies.

  • The force of hitting the insect

  • makes the spit splash up around the bug

  • "And it is able to penetrate all the tiny cracks

  • and crevices within the insect

  • increasing its contact area."

  • After that impact, the spit thickens again,

  • trapping the insect in the goo.

  • It's so sticky that the frog needs to

  • shove its eyeballs onto its tongue

  • in order to loosen the spit enough to swallow its morsel.

  • It's that combination of the soft tongue

  • and the sticky saliva

  • that lets frogs scoop up prey in an instant.

  • Of course not even super spit can help the frog

  • if it bites off more than it can chew.

  • For Scientific American, I'm Lydia Chain.

This cricket is about to be dinner.


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B2 中高級 美國腔

粘滞的青蛙舌头(Soft, Sticky Frog Tongues Slurp Supper)

  • 6 1
    joey joey 發佈於 2021 年 05 月 15 日