Fungi
Fungi play an important role in the health of the ecosystem in a terrarium. To learn about their role in nutrient cycling and decomposition, please check out the the page on microbes. This page is devoted to the rare gift of a mushroom bloom in the terrarium.
What is a mushroom?
A mushroom in the fruiting body of a fungus, generally of the phylum Basidiomycota. The majority of the organism lives underground as a mat of fungal roots (hyphae), called a mycelium. The mycelium is composed of little hair-like hyphae, which act to digest and extract nutrient from organic matter in the soil. This can consist of rotting plant and animal matter, fallen leaves or wood. The mycelium continues to grow, and you might notice it inside your vivarium as a fine webbing in your substrate. You might mistake it for mold. Once the mycelium has grown significantly in size it can begin to form the fruiting bodies which will become mushrooms.
How to grow mushrooms in your terrarium
So how you go about getting mushrooms to grow inside your vivarium? The short answer is luck. However, there are some measures you can take to increase your chances of success. The fungal mycelium grows by eating decaying organic matter in your terrarium. Therefore, a substrate which has a thick layer of organic material, such as leaf litter and wood chips is more likely to support a fungus than a strictly inorganic substrate. Fungi also tend to grow within decaying wood and therefore larger amounts of driftwood may facilitate fungal growth.
There are also some steps that you can take to seed your terrarium with fungi. The simplest method is to break up an existing mushroom cap and spread it around the terrarium. Using a mushroom which had bloomed in another terrarium ensures that the species is capable of growing in vivarium conditions, but may be hard to come by. I that some hobbyists have innoculated their vivariums with commercial micorrhizal mix, but I have not heard any annecdotal reports of them leading to mushroom blooms. The micorrhizal fungi may increase your plant growth. If you have experience innoculating with mycorrhiza, please let us know!
Are mushrooms dangerous?
People frequently ask whether mushrooms are safe to have in your terrarium. Or even more alarmist, ask how to kill mushrooms. The safety of mushrooms in the vivarium is still an open question. The majority of mushroom species are a harmless, curious indication of a healthy picosystem. There are, of course, poisonous species of mushrooms. Most poisonous fungi are harmful only when eaten, and frogs don't eat mushrooms (at least not directly). I am not aware of any reports of an animals becoming ill due to contact with a mushroom in the terrarium. If a report exists, I'd love to hear it. There are reports of severe mushroom blooms filling a terrarium with spores, however frequent misting should be effective at cleaning the air of spores.
