STEVE INSKEEP, Host:
And while we're swimming with the nose plugs, let's move onto this story about seafood. Before cooks can steam mussels, they have to make sure they tear off something called the mussel's beard. That's the bushy, little bundle of tough threads that the mussel uses to anchor itself to a rock or to a pier. Scientists have just figured out how this stringy web can have such an iron grip. NPR's Nell Greenfieldboyce reports.
NELL GREENFIELDBOYCE: Living on a rocky seashore isn't easy, Matt Harrington says. It's not just the endless crashing waves that are trying to rip mussels off the rocks.
GREENFIELDBOYCE: But also, they're being blasted with debris like small pieces of sand, and other debris in the water that are basically acting like sandblasting, and creating these really abrasive environments to live in.
GREENFIELDBOYCE: Still, the mussels hang on tight with the help of their beard.
GREENFIELDBOYCE: And these fibers are stiff but stretchy, and they basically function as kind of a holdfast and a shock absorber.
GREENFIELDBOYCE: Harrington works at one of the Max Planck Institutes in Potsdam, Germany, where he tries to get ideas for new, manmade materials by studying ones found in nature. He says the mussel's beard has a combination of stretchy and hard that's unusual.
GREENFIELDBOYCE: To combine these two properties, it hasn't really been achieved yet in engineering materials.
GREENFIELDBOYCE: So he and his colleagues wanted to see how mussels did it. And they're reporting their findings in the journal Science. It turns out, the beard threads have a core of a soft material similar to what you'd find in a tendon. That's surrounded by a hard coating. The coating is made of proteins laced together with atoms of iron. What's more...
GREENFIELDBOYCE: The coating has this really - kind of weird, rough texture - very, like, knobby.
GREENFIELDBOYCE: Harrington says tiny cracks can form in the threads, but only in between these knobby bits. That distributes damage over the length of the thread, and lets it stretch without completely breaking as the mussel gets pummeled by the waves.
Nell Greenfieldboyce, NPR News.
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