Ahh, the smell of the sea again.
Sunday took me back to the same stretch of beach where, six years ago, I first wrote about bladderwrack and its curious air bubbles. Same tide line, same sand, same seaweed washed up in dark, glistening clumps. I found myself crouching over another cluster almost without thinking — and then I noticed I was doing exactly what I always tell children to do: looking closely, before deciding what I thought.
What I Noticed First
Before anything else — just the observation. The bladders were still there, round and paired along the midrib, just as they always are. Some fronds were plump and full, holding their shape. Others had gone flat and papery, more like the bubble wrap they get compared to, but deflated. A few clumps were small and scattered, barely holding together, dried nearly black in the sun. After several heat waves, it was perhaps what to be expected.
That’s an observation, not yet a conclusion. It would be easy to jump straight to “the seaweed is struggling” or “this is climate change” — but a good beachcomber, like a good thinker, separates what she sees from what she decides it means. So: what did I notice? Bladders present, but variable in size and firmness. Some fresh, some dried out early. Worth a closer look.
What I Wondered
Bladderwrack (Fucus vesiculosus) uses those air-filled bladders to float its fronds upright in the water, closer to sunlight, so it can photosynthesise and exchange gases more efficiently when the tide is in. It’s a foundation species — one of those organisms whole rockpool communities are built around, sheltering snails, crabs, and juvenile fish.
It’s also, it turns out, one of the species scientists are watching closely as the sea changes — and the story researchers are finding is a genuinely surprising one.
Marine biologist Alexandra Kinnby at the University of Gothenburg has been growing bladderwrack in water as acidic as the ocean is projected to become by the end of this century. At first glance, the results look like good news: in more carbon-dioxide-rich water, the seaweed photosynthesises harder and grows about a third faster and bigger than it does today. More seaweed, more habitat, more carbon soaked up — what’s not to like?
But under the microscope, that faster growth turns out to be a trick. Bladderwrack uses calcium and magnesium from seawater to build the compounds that give its cell walls strength, and in more acidic water it can’t take up those minerals as well. The tissue that results is riddled with cavities — porous and spongy rather than tightly packed — and in lab tests it took only about half as much force to tear the acid-grown seaweed apart compared with today’s. Bigger, but far more fragile: like a plant that’s shot up quickly but grown weak instead of sturdy. Since storms are expected to get more frequent and powerful as the climate warms, that’s a dangerous combination — whole fields of bladderwrack risk being ripped from the rocks and swept away, taking the crabs, snails, and young fish that shelter there with them.
Researchers studying bladderwrack elsewhere have found related pressures too: short, sharp marine heatwaves can wipe out local populations in shallow, sheltered spots exactly like the ones bladderwrack favours, and warming combined with falling salinity (from heavier rainfall) makes things harder still. Different mechanisms, but the same seaweed, caught between several changes in the sea at once.
None of that means the clump in my hand was a climate casualty — one afternoon’s beachcombing isn’t data. But it reframes the “I wonder why some bladders are flat, and some are full, and why this patch looks bigger than I remember” question a five-year-old might ask. The honest answer now includes: bigger doesn’t always mean stronger — a genuinely new, and genuinely useful, layer to add to the old “it’s an air bladder that helps it float” answer.
Why This Matters for How We Talk With Children
I’ve been thinking about this alongside a video I watched on thinking habits — aimed at adults in meetings, of all things, but it landed differently for me as a biomimicrist. Two ideas jumped out:
Separate your observations from your conclusions. The video’s example was workplace feedback, but it’s exactly the skill beachcombing teaches for free. “I notice the bladders are different sizes” is a fact a child can state with confidence. “I think it’s because of the warm weather” is a conclusion — one they’re allowed to hold loosely, revise, or be wrong about. Teaching children to tell the difference doesn’t just make them better scientists later; it protects their confidence now. They don’t need to be right about why, only honest about what they saw.
Start at the end, then explain your reasoning. When a child says “the seaweed feels different today,” resist the urge to supply the answer first. Ask them to state their conclusion — however small — and then walk backwards into what they noticed. It’s the same structure researchers use to write a paper, just scaled down to a five-year-old on a beach.
This is, in the end, still what the first bladderwrack post was about: giving children room to look, to ask, and to invent. The only difference now is that some of their questions — why is this one smaller, why did this patch not come back this year — deserve a real answer that includes the changing climate, offered honestly and without alarm.
An Idea Worth Sketching
Back in 2020, our beachcombing led to a child’s idea for floating solar panels inspired by bladderwrack’s air bladders — buoyant, wave-riding collectors built from sustainable materials. It’s worth returning to that idea now with a climate lens: what would it take to build something that, like bladderwrack itself, could tolerate a warmer, less predictable sea? Would a design need to flex more? Shed excess heat? That’s a good next sketching prompt for a curious child (or grown-up).
As always — I’d love to hear what you and your children notice, wonder, and invent from your own bit of shoreline.
Source: Alexandra Kinnby et al., “Ocean acidification reduces tissue strength in a non-calcifying foundation seaweed,” University of Gothenburg / Current Biology, reported here.
Featured Photo: Two pieces of Bladderwrack. The larger seaweed was collected six years ago, at approximately the same spot and time of year. Please note that any differences might be completely random.
Frequently Asked Questions
What is biomimicry?
Biomimicry is the practice of looking to nature for solutions, then applying what we learn to design and problem-solving. Instead of inventing from scratch, it means studying how plants, animals, and ecosystems have already solved a challenge — like staying cool, collecting water, or absorbing carbon — and adapting that strategy for human use.
How does biomimicry help address climate change?
Nature has been adapting to extreme conditions for billions of years, so many organisms already hold working solutions to problems we now face at a larger scale — cooling buildings without electricity (termite mounds), collecting water in drought (the Namib beetle), protecting coastlines from storms (mangrove roots), and capturing carbon (corals, forests, kelp). Biomimicry means studying those solutions and applying the same principles to human design.
How can children get involved in biomimicry?
Children don’t need special training to think like a biomimicrist — just curiosity and a habit of asking “how does nature solve this?” Simple ways to start include a backyard scavenger hunt for nature’s patterns, a “design-an-animal” challenge for a changing climate, or building a small model (like a passive-cooling structure or a water collector) inspired by something they’ve observed outdoors.
Is biomimicry only for scientists and engineers?
No — biomimicry is as much a mindset as a profession. Anyone can practice it by observing nature closely and asking design questions. Professional biomimicry practitioners apply it in architecture, materials science, and engineering, but the same core skill — careful observation followed by “what if we built it that way?” — is exactly what this post’s classroom and family activities are designed to build in children.
Åsa Jomård
In 2015, Åsa completed a course in Biomimicry: A Sustainable Design Methodology at Minneapolis College of Art and Design. With over 10 years of experience exploring nature for inspiration and as a former member of Ben, Biomimicry Education Network, she brings both academic background and creative teaching experience to her work. Her materials seamlessly integrate stories, nature observations, and design challenges, making them perfect for inquiry-led learning in early primary contexts.
AI was used as a Thinking Partner.