1These California mussels huddle together, hanging on to this rock for dear life.
2But if the tumultuous waves should knock one loose, it's in trouble.
3Disconnected and all alone is a very dangerous place to be.
4So, it timidly pokes its foot out from between two armored shells...
5and makes this.
6A byssal thread: a springy lifeline.
7It only takes a few minutes to make a single strand.
8But now the mussel is literally hanging on by a thread.
9It'll keep going until it's made 50 to 100 of these connections -
10what some call the mussel's "beard".
11It uses it to fasten securely to a rock...
12preferably next to other mussels.
13It'll even use its foot to drag itself closer to friends.
14And why not?
15They make great neighbors.
16Sticking together makes it harder for hungry predators and crashing waves to pry them loose.
17Mussels thrive near the shore where waves churn up food for them to filter out of the water.
18If they find a good community... they can stay glued in place for decades.
19Long enough for these barnacles to start using them as furniture.
20So how exactly does a mussel make a byssal thread?
21Turns out it has a miniature thread-making factory in its foot.
22It all happens inside this long groove that works like a mold.
23Microscopic glands pour in special proteins which fuse together to form the core of the thread.
24Different proteins surround the core, making a tough, protective coating.
25To anchor the thread to the rock, the mussel secretes a foamy glue, cementing it in place.
26The threads are made of similar stuff as the tendons in our bodies that connect muscles to bone -
27super strong but also pliable.
28The glue it uses to hold on is more than just waterproof.
29It actually hardens in water.
30If we could figure out how to make a glue like that, it'd be a game-changer for medicine.
31Especially for uses like mending broken bones and closing wounds in delicate surgeries.
32Like the ones doctors do on fetuses in the womb.
33Now, with their threads all sorted out the mussels can finally relax...
34well, mostly.
35I mean, you can't blame them for being clingy.
36They're just a little... shellfish.