Sticky. Stretchy. Waterproof. The Amazing Underwater Tape of the Caddisfly | Deep Look
What do you do if you are a tiny caddisfly larva growing up in a torrent of water and debris? Simple. You build a shelter out of carefully selected pebbles and some homespun waterproof tape.
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We already mimic them to make fly-fishing lures. But now scientists believe copycatting one tiny insect could hold promise for repairing human tissues and setting bones.
Instead of stitches and screws, doctors may soon call on the next generation of medical adhesives — glues and tape — to patch us up internally.
The inspiration? Caddisflies, a type of stream-dwelling, fish-baiting insects that live in creeks all across the United States.
As a larva, the caddisfly constructs a tiny tube-like house for itself, called a case, entirely underwater, using pebbles and its incredible homespun tape as the mortar.
Thanks to the qualities of this amazing silk, the case not only holds up when submerged, it is strong enough to protect the caddisfly’s soft lower body amid forces many times its body weight.
Any tape, including this one, has two basic components: the flat ribbon, or backing, and the layer of sticky stuff, or the glue. From the materials science standpoint, caddisfly tape is extraordinary in both departments.
Caddisfly silk biomimicry is only in its infancy, but one day, a similar compound might be used inside the body, which is another watery environment, to mend soft tissues and even repair hard ones, such as teeth and bone.
In the streambed, or brook, the caddisfly’s case eventually becomes a cocoon. Like its land-based cousins, the butterflies and moths, from whom it diverged 250 millions years ago, the caddisfly larva undergoes a metamorphosis. It seals up its case with a so-called “hat stone” and emerges months later as a winged adult.
--- Where do caddisflies live?
Caddisflies are most common in shallow, cold, turbulent streams, where the water is highly oxygenated.
--- What do caddisflies eat?
Caddisflies are herbivores, they eat decaying plant matter and algae on the rocks in the streams where they live.
--- What is so special about caddisfly silk?
Engineers are interested in two attributes of caddisfly silk. First of all, it can bond to something, such as a pebble, underwater, which no glue people have made can replicate. Second its “viscoelastic” properties allow to it harmlessly absorb physical forces. When stretched, it doesn’t snap back like a rubber band. It returns to its original shape slowly and safely. It's an engineering marvel.
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