There’s a strange being inhabiting our planet. It’s made up of at least two separate organisms, each from different kingdoms of life, living together as one. And it’s growing on bare ground, trees, rocks and buildings from the desert to the arctic to your backyard.

It’s lichens!

Beautiful and occasionally downright adorable, lichens are often mistaken for simple fungi, but that’s only part of the story.

 

Lichens are actually symbiotic composite organisms made up of a fungus and some form of algae or cyanobacteria. The fungus is the dominant one in the relationship in terms of size, but it gets all of its food from the nutrients produced photosynthetically by its algal partner.

There are almost 20,000 species of lichens, which come in a wide diversity of shapes and colors.

I’ve always wondered – how does something made of two very different, unrelated organisms, manage to reproduce? It turns out, lichens reproduce in a couple of different ways. Sometimes, the fungus will undergo sexual reproduction, releasing spores, which land where they may and hope for the best in terms of finding a suitable photosynthetic partner. But for these unique organisms, asexual reproduction is a heck of a lot easier when it comes to offspring survival. Lichens can reproduce by simply breaking apart. Dry portions of the lichen can crack and crumble away. When the pieces that have fallen off reach a wet surface, they grow into a new lichen. But they have another fancy trick too. Lichens can produce little balls of algal cells that are wrapped up in fungal tissue. These little clusters, called soredia, are carried away by the wind,effectively dispersing both partners together.

Lichens may not seem all that important to us, but they can play a major role in very cold and dry climates. In the arctic, for example, lichens are extremely abundant and act as major food source for caribou and reindeer.

 

Other animals incorporate lichens into their nests.

 

But there’s a problem. Due to factors associated with climate change, reindeer and caribou are having a harder time reaching lichens during the winter months when they typically depend on a steady supply for food.

Also troubling is the fact that lichens are particularly sensitive to atmospheric pollution. But there’s a bright side. Scientists are now using lichens to monitor air quality. There are whole books written about it!

While lichens may not be an organism, rather organisms, we think about often, it seems they’re yet another example of the small wonders in nature that play a big role in the world around us. And maybe you’re likin’ lichens just a little bit more now.