Lichen are plants and fungus that create a mutualistic relationship greater than the sum of their parts. What can we learn from them?  |
| Common Greenshield Lichen. Flavoparmelia Caperata. Photo by Amy Coffman Phillips |
Natural History
How does the lichen fit into this forest?
Walking through the forest for my first iSite in the Harvard Forest, I came upon this beautiful lichen growing on a red maple tree. Up close, it looks like flattened lettuce or cabbage growing in these romantic formations, an example of a foliose (leaf like) lichen. And lichen is unique because it is not one organism, but a symbiotic relationship between two organisms: fungi and algae. To form a lichen, the fungus either encloses the algae in fungal tissue or penetrates the algal cell wall in order to harness their photosynthetic abilities. The fungi form the structure and then recruit algae to come live with them, and the algae benefits from the protection the fungi provide as well as their ability to capture water and nutrients. The mutualistic relationship between these two organisms (although sometimes commensalistic or even parasitic depending on the species) is greater than the sum of its parts because it allows both organisms to survive and thrive in areas they would not be able to alone. Their relationship creates benefits for the ecosystem as a whole as well because as rain water falls down the bark of a tree, it gathers nutrients from the lichen which feeds nitrogen and other nutrients to the soil, and then by extension, the tree and other plants.
How does the lichen fit into this forest?
Walking through the forest for my first iSite in the Harvard Forest, I came upon this beautiful lichen growing on a red maple tree. Up close, it looks like flattened lettuce or cabbage growing in these romantic formations, an example of a foliose (leaf like) lichen. And lichen is unique because it is not one organism, but a symbiotic relationship between two organisms: fungi and algae. To form a lichen, the fungus either encloses the algae in fungal tissue or penetrates the algal cell wall in order to harness their photosynthetic abilities. The fungi form the structure and then recruit algae to come live with them, and the algae benefits from the protection the fungi provide as well as their ability to capture water and nutrients. The mutualistic relationship between these two organisms (although sometimes commensalistic or even parasitic depending on the species) is greater than the sum of its parts because it allows both organisms to survive and thrive in areas they would not be able to alone. Their relationship creates benefits for the ecosystem as a whole as well because as rain water falls down the bark of a tree, it gathers nutrients from the lichen which feeds nitrogen and other nutrients to the soil, and then by extension, the tree and other plants.
Lichen exist in most every ecosystem on the planet from arctic tundra to deserts. While they have adapted to many different climates and conditions, they are also sensitive to environmental disturbances, such as air pollution because they are not deciduous and absorb nutrients from the atmosphere, rain and dust rather than roots. For these reasons, they are bioindicator species for air quality as well as ozone depletion and metal contamination.
Lichen also grow in unique structures, different than those that fungi or algae use alone. They are built in layers. The outer layer is a conglomeration of fungal cells that form a protective cortex. Below this layer is a layer of algae embedded in a densely woven layer of fungal hyphae or the long branching structures of fungi,. Below this layer, the third layer is comprised of densely woven fungal hyphae without the algae, called the medulla. The fourth and bottom layer is called the lower cortex and resembles the top layer and is also composed of densely packed fungal hyphae and rootlike rhizines which attach the lichen composite to the structure on which it grows. Because these roots are for structural stability and not nutrient gathering, lichen have the ability to grow on surfaces that other organisms cannot, such as tree bark and bare rocks.
Different types of lichen reproduce in different ways, typically asexually through spores but vegetative and even sexual reproduction occurs in different species. In the case of this lichen, it is similar to an isidia in that it sends up shoots that break off for mechanical dispersal of genetic information. Lichen are able to desiccate and survive long periods with very little water, entering into a state of suspended animation, ready to rehydrate when water becomes available. This ability allows them to survive long periods of temperature extremes, radiation, and drought in harsh environments.
Strategies/Mechanisms
What are the deep patterns we can take away from the lichen?
- Mutualistic communities of organisms create conditions that are better for themselves as well as the organisms around them, and this symbiosis allows them to withstand conditions together that they would not be able to alone.
- The fungi develop the structure on which the algae grow. Fungi create a densely woven structure of tiny branches that embed and encapsulate the algae in order to harness their photosynthetic abilities. The organism bodily structures of each organism change in order to accommodate their partner, and they cannot survive alone.
- Lichen absorb nutrients from the air and water through their cell walls. When environmental disturbances occur, the algae absorbs these contaminates molecularly and is destroyed, killing the lichen composite. For this reason, lichen are a good bioindicator species and signal environmental disturbances we cannot yet perceive.
Design Principles
How can these strategies naturally influence design innovation?
- Encapsulate harmful substances in a membrane for safe storage at room temperature.
- Grow fibers at the nano scale that will self-assemble into prescribed patterns.
- Design smart materials that passively absorb air- or water-based compounds in order to indicate changes in the system.
Design Application Ideas
What are potential innovations that could result from this natural inspiration?
- Store food at room temperature by encapsulating it in a tasteless, edible membrane that prevents spoilage.
- Preserve vaccines at room temperature by encapsulating active ingredients in a dissolvable membrane.
- Design passive air quality monitors that absorb harmful chemicals or pathogens and change color to indicate their presence.
- Design water quality monitors that test for chemicals or pathogens by absorbing and changing color to indicate their presence.
Biomimicry Professional Certificate Program
http://en.wikipedia.org/wiki/Lichen
What a beautiful photo! Looks like an inspiring and intellectually stimulating trip. Enjoy! I'm caring for an adorable little one with eczema, who is miserable with the itching. Poor baby!
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