I’ve Taken a Lichen’ To You ;D
At first glance lichens don’t exactly fill you with wonder and amazement but more a sort of “oh-cool-that-rock-has-mold-on-it…”ment. However we know better than to judge a book by its cover and you can be forgiven for this as the popular opinion about lichens up until the 1800s was that they were an example of rocks spontaneously coming to life. Instead lichens exist as a near perfect symbiotic organism between a fungus and a photosynthetic algae or cyanobacteria. The fungus provides protection, water and in some cases minerals from the substrate (sometimes acquired by dissolving rocks) while the algae produces the food source via photosynthesis. The truly interesting thing about this mutualistic lifestyle is that while we can grow all species involved separately in the lab, they don’t look the same. The fungus grown without the algae is simply a mess of hyphae yet when the algae is introduced it changes into its usual form that best utilizes the photosynthetic abilities of its partner. It’s also been found that introducing different species of algae to the same species of fungus can lead to strikingly different morphologies.
Lichens are found in some of the harshest environments on Earth such as the Antarctic, deserts or even certain species on piles of toxic slag. Despite this most species are incredibly sensitive to air pollution and are a good indicator as to pollution levels.
Images: 1, 2, 3, 4, 5