字幕表 動画を再生する
-
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.