Exploring the amazing world of lichens
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Lichens are a symbiotic relationship between algae and fungus. They have been on earth for millions of years. They live on rocks and trees. They also live in soil. They live in all different habitats on all seven continents. Lichens are all around us. But scientists are still learning about what they areand where they live. They are still learning how many different species of lichens there are.
Fungus is any group of spore-producing organisms feeding on organic matter. This matter includes molds and yeast. It includes mushrooms and toadstools.
Algae is a simple, non-flowering plant. Algae contain chlorophyll and produce sugar. They produce it through photosynthesis, like other plants. But algae do not have true stems or roots. They do not have leaves or vascular tissue. Most other plants do have these things. Lichenization is a fungal lifestyle. Therefore the name of lichen is the name of the fungus component.
When you look at a lichen, what you’re looking at is the “house” that the fungus and algae grow together. Scientists call this house a “thallus.” When algae and fungus come together to form this house, we see a lichen. This partnership is called a symbiotic relationship. That's because it helps both the fungus and algae survive. Research has shown that lichens are not a natural biological group. This means they do not all come from a single common ancestor, lichens have many origins. Currently there are almost 20,000 species of lichenized fungi known.
In this symbiotic relationship, the fungus and algae benefit from being associated with each other. The fungus provides the house, its shelter. Also called the thallus. This shelter helps the algae survive. It survives in habitats where it would otherwise be exposed to the elements and possibly could not survive. The algae provides food for the fungus, in the form of sugar. The sugar is a byproduct of photosynthesis. That occurs within the algae.
Lichens are very important for the environment. They are an important food source for many animals. They provide nest materials for birds. They provide habitat and material for biomimicry for insects and other organisms.
Lichens are also important for humans. They provide natural dyes and perfumes They provide litmus paper and even food. Humans even use lichens as bio-indicators, organisms that help humans monitor the health of the environment. Some species of lichens are sensitive to environmental pollution. Their presence or absence can help us understand more about the health of the environment, like air quality.
Lichens produce over one thousand different chemical compounds. Most of them unique to lichens. These compounds include acids and pigments. Some chemicals may even fluoresce under UV light, making them important components for lichen identification.
Lichens have DNA. It is used to identify lichen and compare relationships amongst and within species. DNA analysis has been an important tool for lichenologists. It helps them identify and understand the biodiversity of lichens.
Tune into the free Smithsonian Science How webcast, "What's a Lichen? How a Smithsonian Scientist Studies a Unique Symbiosis." You will meet Dr. Manuela Dal Forno. The webcast will be on Thursday, November 14. You can see it at 11 AM and 2 PM EST. There will be a live video stream and interactive polls and a Q&A. Manu will take questions about lichens and her research. Sign up and tune in here: https://naturalhistory.si.edu/education/distance-learning/what-is-lichen-symbiosis
Get a student worksheet for the webcast. Get the teacher guide for the webcast.