Plant Biomimicry: Thigmotropism
Rebecca Eagle, November 13, 2017
Over the past three years in our program, I’ve had many opportunities to converse with interested folks about the wonders of plants. Plants do some pretty miraculous things, no doubt. At the very core of their existence, they are required to survive ‘in place’. How many other living organisms on Earth can claim this feat? Very, very few things can accumulate life’s requirements (reproduction and resource acquisition), without movement. Not to mention, plants also must adapt to local conditions: contamination, weather, drought/flooding events, and more. While animals, insects, and birds can move when their environment gets unfavorable, plants must shelter in place and utilize strategies that they’ve evolved over the millennia of time they’ve been on this planet.
A favorite plant of many inquisitors of plant biomimicry is the Venus Fly Trap (Dioneae muscipula). Why wouldn’t someone
admire this plant?! It eats meat, but cannot move from place because it lacks musculature and because it needs to stay rooted in the ground to obtain water, minerals, and necessary stability to stay erect. Many are surprised to learn that this insectivore is native to our own United States, found chiefly in wetlands of the Carolinas. Let’s discuss the biology of the Venus flytrap, and then talk about its inspiration for design applications.
The Venus Fly Trap lives in nutrient-poor wetland soils, particularly low in nitrogen and phosphorus. Plants require these elements and all plants have strategies that allow them to acquire them from their environments—sometimes in very unique ways! Remember, though, that plants can’t move. They rely on things that are accessibly near them. Soil and the atmosphere being the mediums for most plants, cannot be relied on by the Venus flytrap. This constraint doesn’t faze it! Other organisms come to plants, right? Aphids, pollinators, nectarivores, and other critters visit plants for meals of all cuisines (vegetation and nectar), and this carnivorous plant evolved to capture the nutrients and energy from these insects to ensure its survival throughout time! (The first written documentation of the Venus Fly Trap was noted in 1760 in North Carolina, by North Carolina Colonial Governor Arthur Dobbs ). A question I am frequently asked is whether the plant does photosynthesis. Yes, the Venus flytrap does have the same anatomy and physiology required to be in the Kingdom Plantae. It is not uncommon to hear that they rely solely on insects for nutrients, but this is not true. Insects are merely the back-up mechanism for the minerals that a play would obtain from the soil, not the CO2 or sunlight energy obtained above ground.
We get it, the Venus flytrap eats insects for nutrients… but how? (Video: 4-minute YouTube video of Venus flytrap in action). When a larger-sized insect (flies, ants, spiders, grasshoppers, i.e.), lands on the inside of the leaf blade, the weight of it will eventually trigger minute hairs. These trigger hairs will respond (0.1 second response time), by closing the trap. Ideally, the prey will be inside, but, as you can see in the suggested video, this mechanism is not fail-safe. As is in nature and life, sometimes we lose the game.
The response of the trigger hairs is an example of a nastic movement and thigmotropism. Thigmotropism is the act of responding to the direct stimulus of touch, such as a fly landing on the inner leaf blade and bumping into one of the two or three trigger hairs. Nastic movements are controlled by hormones, more so than by a direct stimulus. Once the direct stimulus causes the thigmotrophic response, auxin (a plant hormone) stimulates cell expansion as a rapid growth response. In short, the cells inside the leaf of the Venus flytrap are told to swell up quickly, which causes the leaf blades to close. This is the same physiological response and movement that is witnessed when a flower of an angiosperm plant opens and closes in response to light! (As an aside, auxin does some pretty rad things in plants that I encourage you all to read about in your down time!).
Bio-inspiration from the Venus Flytrap
How could we not be inspired by this amazing plant?! I’ve talked in previous posts about some possible applications for designs based on the mechanisms of the Venus flytrap: baby gates, pet gates, sensors for factories, sensors for home safety, etc. I won’t rehash that conversation. The general idea involved here is the passive sensing with quick response that uses only clean energy.
While the response mechanism is certainly worthy of investigating, I would add in the importance of Life’s Principles as an additional means of bio-inspiration from the Venus flytrap. If we consider the rationale involved in utilizing insects for survival, we witness the ability of this natural organism to obtain its needs from the local environment in absence of the preferred mechanism for sequestration. As far as I know, the Venus flytrap isn’t shipping in her flies and spiders from the west coast. She has found a way to survive and thrive with what is near to and available to her. She is substituting a necessary product for another locally obtained product. She carefully considered her choices and chose to adapt and evolve, rather than die.
Of course I am getting a bit anthropomorphic here, but my goal is to encourage companies to look at the bigger picture of what is important to the planet, to its business, and to its customers. The amount of money and natural resources that are invested in product development could, perhaps, be re-evaluated to better meet the needs of the business by responsibly utilizing local supplies, rather than shipping them into the area. The re-evaluation might discover that the location of the business itself is better suited to be near the customers it most services—avoiding the strain of shipping far distances.
As I leave you, to spend more time preparing for my upcoming comprehensive exams, I would like to mention this quote I read in Botany for Gardeners (Capon, 1990). The preface of the quote describes the means by which antifreeze was developed, inspired by ‘leaf antifreeze’ (increasing the concentration of sugars in the protoplasm to lower the freezing point inside the cells). “Plants have been ahead of human invention by several million years.” Consider this as coming from a 1990’s book for gardeners, not for engineers, designers, or biomimicry-enthusiasts. This is written by someone who just appreciates plants for the value they bring to all of us in such a variety of ways. I encourage all of you to continue to read about the wonders of plants and be inspired by all the great things they do… all without leaving home!
The habitat of the Venus flytrap is limited to a small area of the Carolinas. Modern development threatens this already minuscule area with increasing take-over. Consider visiting the website of The Nature Conservancy to learn more about the plant that Charles Darwin has called “the most wonderful plant in the world.”1
 The Nature Conservancy, accessed November 13, 2017. https://www.nature.org/ourinitiatives/regions/northamerica/unitedstates/northcarolina/explore/venus-flytrap-brochure.pdf?redirect=https-301
 Capon, Brian. (1990). Botany for Gardeners: An Introduction and Guide. Portland, OR: Timber Press. pp. 86.
Last week was Spring break and we had this great opportunity of going and presenting in digiFAB conference in Boston about Biomimicry through one of my Sponsors TIES! Lots happened and I was excited to meet some great people in the field and had butterflies about my own talk. My excitement was doubled and butterflies gone with keynote speaker, Sherry Lassiter director of Fab Foundation, You can see her in picture below talking about different movements within Fab Foundation as well as the Fab network.
Dale Dougherty, then talked about Maker movements, I have been following Dale’s maker group (he runs the Make: which you can subscribe to) and was thrilled when he talked about “Autonomous Boat [that] Went from California to Hawaii and Beyond”. I read about this project when first published in Make: and was happy that the boat had been picked up by a ship in New Zealand and was in display there.
The 2 day conference was packed by amazing talks, I like to shortly go through few of them.
FAB City A 40 year goal from Barcelona to empower citizens to be creators of their own city; “locally self-sufficient and globally connected”. For me, it seemed as a society that doesn’t need a centralized governing body, but where citizens create materials based on their needs, recycle when possible and are connected to many more cities around the globe.
Tomas Diaz from FABCity also talked about the model and plans they have to reach this goal in Barcelona. he talked about POBLENOU where its supported by local and international community to become a FAB city.
Rachel Ignotofsky; Women in Science , and the importance of design and arts in our life, how arts influences our perceptions and why is it important to use it in our learning kits.
3D printes, bluedragon made with business in mind, where you can print 4 colors in one product, you can mix different colors into one or just use one at a time: FIREPRINT. If anyone wants to put money together to get one, I am in! Check out their case studies, from combating Zika to cosplay, you can do all!
Second day was nothing short of amazing talks as well, we first heard from Neil Gershenfeld, Director, MIT Center for Bits and Atoms, of his work on developing tools/processes for FABLAB, I did not see it coming where he talked about Nature! In below picture he was explaining how creating modules is similar to protein formation in our body.
He also talked about how we are moving to Ubiquitous and with these changes, how his lab is working on developing the tools, materials, to functional part.
And one of my favorites; Global Humanitarian Lab, talk by David Ott, Co-founder, Where they aim to bring FABKits (costing around < $10k) to refugee camps. David talked about what would be in the FABKits and how everything needs to be packed into container that could be transferred by 1 or 2 person. He talked about limitations, needs and potentials of these labs. He talked about makers/ people who need the opportunities we easily can access in our cities.
There was many more talks which I highly recommend attending. This year, there was an addition of having workshops and we had ours on Biomimicry in Artisan’s Asylum in Somerville. Another place to put in your places to go!
So What did we talk about! We talked on first day about Spiders and Ornilux, Tardigrades, Spikemoss and Stabilitech/Biomateria and How they relate to maker group! As we grow in FAB network and as we move toward FAB cities, Can we benefit from nature’s stories? Can we learn from 3.8 billion years of lessons? Our hope is to learn and make more sustainable decisions. Either in creating new FAB equipments, or materials used. We see a movement that will grow potentially in years to come and we want to instill biomimicry thinking in its foundation!
“Plants are amazing!” This is something I hear a lot from non-botanists. Of course, I know plants are awesome, but every time I turn around, I learn something new and exciting. This semester was no exception. Tasked with a project in my Biomimetic Design class, led by Dr. Petra Gruber, I walked into the meadow to find inspiration– literally.
On a very wet, cold, rainy day in October, I walked to a meadow within our field station property (Bath Nature Preserve, Bath Twp., Akron, Ohio) and found a section to investigate. Indian grass (Sorghastrum nutans) towering over my head, I decided to stop at 20 steps and set up a 1m x 1m plot to sample. October in a meadow doesn’t give you very much to identify, but goldenrod (Solidago spp.) and Indian grass (S. nutans) were plentiful among a few baby asters, Galium spp. (aka ‘Cleavers’ or ‘Bedstraw’), wild strawberry (Fragaria virginiana),clumps of unidentifiable grass and moss. I measured heights of stems and area covered, took the percent coverage to determine how much each species covered the plot,and took several picture views for record. After returning to campus, I created a hand-drawn schematic of the plot.
A few weeks later, I returned to the same plot. Apparently my methods of counting and direction are spot-on because my last step landed on a pen I had dropped on that rainy day a few weeks earlier! If you’ve ever done field work, you understand how amazing it is that I found a PEN in the middle of a meadow over 2 meters high! This time I was there to measure the ability of the meadow to hold a load. I admit, I didn’t think the stems would hold up… being so late in the year and being dried out. As usual, though, plants are amazing and surprised me yet again!
I decided to test the load by creating a 1m x 1m foam board that was sturdy, yet lightweight. I placed the board directly over the plot, placing flags on each corner. The flags allowed for a visual cue to observe movement of bot
h plants and the board, as well as giving a reference point at which to measure the height of the board after each addition of weight. After the foam board was placed on top of the plants, I measured the height at each corner (flag) for the “initial” height. I added one heavy book and measured the height at each corner. Subsequently, I added increasing weight and measured the heights. At 3 books (6.7kg), the system (the meadow plot) could no longer hold the weight. Because this was the same plants were used over the entire experiment, I believe more weight can be held by the plants in true form.
So how does this happen? Plants are amazing. In the meadow, plants grow up to 10 feet below ground (roots) and above ground. You can imagine how secure this makes these cantilever beams! Here, the Indian grass and Goldenrod grew 1.5m to 2.5m above ground. The stems reached diameters of 2-5mm. You may wonder how the stems did not break when the weight was added. Galileo was the first to record these observations, noting that bending is resisted in the outer layers, not the inner stem as some might think. Several studies have investigated this design, including F.O. Bower (1930) who compared plant stems to concrete, saying, “Ordinary herbaceous plants are constructed on the same principle. The sclerotic strands correspond to the metal straps, the surroundin
g parenchyma with its turgescent cells corresponds mechanically to the concrete.” Equisetum (Horsetail) is another champion plant for many reasons, but here, in this context, it’s a biomechanic superstar. “The hollow stem of Equisetum giganteum owes its mechanical stability to an outer ring of strengthening tissue, which provides stiffness and strength in the longitudinal direction, but also to an inner lining of turgid parenchyma, which lends resistance to local buckling. With a height >2.5 m isolated stems are mechanically unstable. However, in dense stands individual stems support each other by interlacing with their side branches, the typical growth habit of semi-self-supporters.” (Spatz, Kohler, Speck 1998). Again, plants are amazing.
After doing some mathematical calculations (very much estimated
in this case because of the imprecise nature of this ‘experiment’), it is expected that a single Goldenrod stem can support >118% of its biomass! Now, we’re not talking about the strength of steel or lead, but we can see that plants offer us new possibilities when we are designing or constructing new things! Imagine a support feature that is hollow inside and allows for storage in the “stem” as well has having the strength to support weight. Think on a smaller scale: imagine a space in which a stiff, lightweight outer covering is needed to secure something. Imagine the many possibilities that plants offer us to grow using Life’s Principles.
Earlier this month, August 2016, I had the privilege of leading an evening reception for the NASA and OAI Biomimicry Summit in Cleveland, Ohio. (OAI = Ohio Aeronautical Institute). A group of 60 attendees gathered inside the Primates, Cats, and Aquatics Building of Cleveland Metroparks Zoo as we engaged in a discussion of Biomimicry in Your Backyard. I selected three common backyard critters to demonstrate how easy it is to find inspiration in the spaces around us every day: La Plata Armadillo, Eastern Box Turtle, and Children’s Python. This week’s blog will feature our one and only “Chaco” the La Plata Armadillo (Tolypeutes matacus).
As we’ve discussed before, biomimicry is accomplished by two possible methods: 1) Start with a question and look to nature for a solution, or 2) Start with an inspiring organism and discover what problems can be solved using that particular structure or behavior. Working in the zoo setting, I typically start with the latter. Whether I am preparing for our Biomimicry/Ecophysiology class within our Advanced Inquiry Program through Miami University of Ohio and Cleveland Metroparks Zoo, answering a question from one of our educators while preparing a program, or speaking at an event for Great Lakes Biomimicry, this is the case. I am given an animal and I start my research. My starting point is generally: What makes this organism unique? It is in this uniqueness that inspiration jumps out at you! I encourage all of you to try this any time you have a moment outdoors to think. It is really amazing what a person can dream up once the trigger is pulled. We will start at this point with our armadillo inspiration.
What makes an armadillo unique? Particularly, the La Plata Armadillo? I would play the Jeopardy music in the background, but I don’t think it will take you that long to come up with the answer: the carapace. The scutes are hard dermal bone with keratin—very similar to a tortoise shell. La Plata, also commonly called the 3-banded armadillo, has a shoulder plate and hip plate with dermal hinges to allow flexibility. This is the only species of armadillo that is able to roll into a complete ball, courtesy of a head plate and armored tail. The Hairy Armadillo (Chaetophractus vellerosus) contrastingly, has a soft outer shell.
The carapace offers several advantages. Most obviously, perhaps, is protection. The La Plata Armadillo is nearly impenetrable when he rolls into a ball. The only predator that could possibly open this shell needs to have opposable thumbs. However, even with this advantage, most predators would find the benefit (food) is not worth the cost (time) it takes to open. It also offers fortification measures by pinching the opposition in its hinges.
Another advantage of the carapace for this dweller of arid environments is thermal regulation. While all armadillos live in regions with temperatures between 92-97°F, the La Plata Armadillo can survive even hotter climates. One might think the shell would keep heat trapped inside the body, but the dermal hinges serve as climate control, allowing for air flow between the hinges.
Lastly, all armadillos have this really cool ability to travel across water. How?! They can hold their breath for really long periods of time. This allows them to walk on the bottom of riverbeds and waterways. What if they don’t want to walk? Like other mammals, they can suck in air and float across the water! Nothing can stop these guys from getting to the other side!
So I ask … what does the armadillo inspire in you?
Two weeks to finishing my first academic year, I’m feeling inspired to talk about our course on developing a product using biomimicry; Michael introduced it here. For this course, we worked with students from the Cleveland Institute of Art and Nottingham Spirk. Nottingham Spirk (NS) gave us the problem and some deadlines. Milestones we had were for coming up with areas we’d like to target, developing the concepts, and finally refining our product designs.
What is the first step to go from biology to a product or vice versa? It was a bit messy for me, considering I am also still learning about many biological organisms, but I am pleased with our results and the progress we made.
First, we worked on our target audience, drawing mind maps of stakeholders and key opportunities. We divided into subgroups based on our interest in particular key opportunity areas. There was only one condition: having almost an equal number of Biomimicry Fellows from University of Akron biomimicry and designers from the Cleveland Institute of Art on every team.
And then we started… Not sure how to go about it, we looked at current products, specific issues within our key opportunity area, as well as asknature.org, other books and papers on animal’s adaptaptions. By end of February, we were ready to give a report to NS about the issues we were targeting and organisms that could potentially help us and got their feedback.
Our next step was to develop concepts by end of March. Here, we needed to read more and actually think of a specific problem and solution. I would say, while researching current market, it was not difficult to see where we can introduce new products and what’s missing. The more challenging part was abstracting ideas from biology. We had a format to follow similar to asknature.org: it included writing first the abstracted function, then the strategy the model organism uses and finally extracting design principles. This time NS were more specific on which ideas they were interested in having us pursue and which they were not. Then it was time to form new groups based on the latest product ideas we were moving forward with. Now, for our final work, my team focused on one specific product and our concept looked to many organisms (from ducks to rabbits) for inspiration. Our final report is today. yay!
Couple of things I learned:
– It was wonderful to work in groups of various specialties (mine included industrial designer, polymer scientist, product designer and me)
– Drawing/talking about ideas helped in better grasping the biological function.
– When there is no actual structure to follow, the flexibility lends to creativity.
– Having many groups, it was interesting to see what each team has come up with and inspirations are endless.
– Designers are great in making an idea come alive and look appealing!
– There are many complicated texts in biology for non-biologists, but, knowing what function you’d like to learn about makes it much easier to research and pictures do speak 1000 words.
– I’m more excited today than when I joined the biomimicry degree.
Till next time, Happy Biomimicking!