Swans: How do they stay so white? Spit & Sparkle…

Posted on by Live & Learn

Swans are the gentle giants of my local waterways: floating paragons of snowy serenity that cruise peacefully through muddy brown water amid the rowdy confusion of their smaller brethren.

And they present a puzzle. Around them, mallards, Egyptian geese and Mandarin ducks have plumage so varied that it seems like any little speck of dirt or grime would disappear into the design. But the swans, paddling around in water so opaque that their feet can’t be seen, tip their tail feathers high in the air to forage underwater for the deepest plants—yet they re-emerge an unreasonably pure white. How do they stay so clean?

[…]

Just as a swan uses an oily coating to repel water, to get rid of oil it needs a watery coating. And the answer—discovered only three years ago in a paper published in the journal Advanced Functional Materials—is saliva. A swan’s spit is full of proteins that have a water-loving end and an oil-loving end. Once in a while, the bird distributes saliva on its feathers instead of preen oil, and the oil-loving ends stick to the feathers, leaving the water-loving ends exposed.

This makes the feathers attractive to water, and so allows the watery saliva to penetrate deep into the feathers. Once it’s there, it finds channels lined with tiny wedges. The wedge shapes help surface tension push the water from the center of the feather to the edges, sweeping along and clearing out any tiny droplets of oil or fat on the way.

The feathers get a watery deep cleaning as the tiniest oily contaminants are carried away. After a while, air dries the saliva out, and the surface returns to its normal water-hating state while the swan is restored to its pristine purity.

It’s a fascinating system, and scientists and engineers are now trying to replicate it to make self-cleaning fabrics that we could use. But kudos to the swan, for having evolved the perfect spit-and-sparkle system for keeping itself clean.

Read full article here.

— Helen Czerski, from “How Swans Stay White in Muddy Waters” (Wall Street Journal, June 6, 2024)

DK Photo: May 31, 2023. 4:30 am. Cove Island Park, Stamford, CT. More photos of the swans from that morning here.

19 thoughts on “Swans: How do they stay so white? Spit & Sparkle…”

  1. Fascinating!
    However, I could really use some visual aids here. Annotated pencil drawings, ultra slow motion video, whatever! I want to see these little magical channels in the feathers to gain a more detailed understanding of this amazing process!

    THEN, I would like to see this miracle installed on the screen of my smart phone! I absolutely hate fingerprints! 🙂

    So very cool Dave!
    Thank you for starting my Sunday on such a wonderful note! 😊

  2. brings new meaning to ‘spit-polish’ and answers a question that I didn’t know that I had lolling around in my head

  3. Photo: it’s like she was saying, You, Come take a photo of me …

    The author made a very sophisticated/advanced chemical process sound poetic. She must understand it very well to be able to simply it this clearly.
    Thank you for sharing dk, I need to read the full article.

  4. I was thinking the same thing. I would have only been able to explain this with drawings.
    This chemical process is actually used to clean oil spills in the ocean. They should be able to figure something for screens. I’m guessing they did already. But you would have to re-apply. Just like the swan has to spit to get this going.

    1. What we need here is a new button on the side of the smart phone which does the following: Squirts swan saliva onto your screen, and then a windshield wiper comes out and wipes things off. Much like a car windshield washer lol. 🙃

      And goodness knows we shouldn’t stop there. This amazing technology should be applied everywhere possible. I’d like a self cleaning house!

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