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  • To us, it's a tranquil mountain stream

  • But if you're a bug living on those algae-covered rocks in the water?

  • It's a constant underwater hurricane.

  • Powerful currents.

  • Debris swirling all around you.

  • How do you survive?

  • Well, you build a shelter.

  • All you need are some raw materials...and a little tape.

  • That's right.

  • Tape.

  • This is the larva of the caddisfly.

  • This insect has evolved a tool that's eluded us humans so far: tape that stays sticky underwater.

  • As winged adults, caddisflies are a favorite food for trout.

  • Artificial lures mimic them in painstaking detail.

  • But they spend most of their lives as larvae in shallow, turbulent water, which is rich

  • in the oxygen they need.

  • And though its head and legs are covered in a thick layer of insect armor, or chitin...

  • ...its soft, white lower body is more exposed.

  • To the elements, and especially to any passing predators.

  • So the caddisfly has figured out how to build a case...for ballast, protection,

  • and camouflage.

  • It does this by binding together pebbles with a special silk that looks, and acts, a lot

  • like double-sided, waterproof tape.

  • Every case starts with one pebble.

  • It's like...the cornerstone of a building.

  • The caddisfly adds more pebbles, one by one, like a bricklayer putting up a wall, using

  • its tape as the mortar.

  • When he brushes the surface with his mouth, that's his tape dispenser working.

  • It's in a gland under his chin.

  • He's sealing the pebble down.

  • These flies are VERY particular about their building stones.

  • Only the right shape and size will do.

  • If it doesn't fit, it's out.

  • When he finds a match, he fits it into place.

  • Once he tapes down the basic shape of the case, he seals it up from the inside, in a

  • series of barrel-roll maneuvers.

  • The problem with our tape is that when it's wet, it loses its stick.

  • But caddisfly tape is selective.

  • It sticks to pebbles, but not to water.

  • What's more, the ribbon itself is like a rubber band.

  • It can stretch to twice its size and return to the same shape.

  • But it snaps back slowwwwwwly.

  • It's a rubber band that moves like molasses.

  • So the case is resilient.

  • No quick movements.

  • That's a lot safer for the vulnerable larva living inside.

  • Bio-engineers have started to figure out how we could make our own caddisfly silk.

  • Maybe as as a kind of internal surgeon's tape.

  • To replace the metal and string that we use to patch people up now.

  • The magical underwater tape of the caddisfly.

  • Another example of how evolution finds radical solutions to everyday problems.

  • Like how to survive in a hurricane.

  • Hi, it's Amy.

  • Look how tiny these guys are!

  • That's what we do at Deep Look: zoom way way in to very small worlds.

  • If you like it, subscribe!

  • And leave us a comment down below.

  • Thanks so much for watching.

To us, it's a tranquil mountain stream

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ベタベタ。伸縮性がある。防水。驚異の水中テープ「カササギ」|ディープルック (Sticky. Stretchy. Waterproof. The Amazing Underwater Tape of the Caddisfly | Deep Look)

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    謝堯家 に公開 2021 年 01 月 14 日
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