Mycelium or mould? What really grows in your terrarium

What is mycelium in the terrarium and how does it develop?

Mycelium in the terrarium is the underground network of a fungus that forms in moist and nutrient-rich environments. Fungi reproduce by spores, which spread to form a mycelium under suitable conditions. This mycelium looks like white, hair-like threads that run through the substrate, leaves or wood.

In your terrarium, mycelium is often created by fermented leaves, flake soil or white rotten wood – materials that are often used to furnish terrariums. These are not only ideal for the animals in the terrarium, but also for fungi, as they provide a perfect food source.

Mycelium in the forest – The invisible network

Next time you’re out and about in the forest, look out for mushrooms – or rather for what you can’t see straight away: the mycelium. This network of fungi forms a huge network in the forest floor that connects trees and plants. This network is often referred to as the ‘Wood Wide Web’ because it allows plants and trees to communicate with each other and share nutrients.

Plants can use the mycelium network to exchange nutrients such as sugar and nitrogen, for example, but also to send signals about pests or environmental changes. If a tree is attacked by pests, it can warn other trees through the mycelium network so that they activate their defence mechanisms. In this way, the mycelium helps to stabilise the forest ecosystem and connect trees over long distances.

Although research has not yet clearly confirmed that trees can react to weather changes such as storms via mycelium networks, the fact that plants and trees ‘communicate’ with each other via the ‘Wood Wide Web’ is impressive.

During my walk in the forest, I took some fascinating photos of mycelium in the forest myself. You can see how the white threads run through the soil and foliage. This natural network impressively demonstrates how important fungi are for the nutrient cycle in the forest.

Mycelium in the terrarium vs mould – the difference

Many keepers confuse mycelium in the terrarium with mould. Mould is a fungus that usually develops in damp and unhygienic conditions and can be potentially harmful to the animals in the terrarium. Mould often has a greyish or greenish colour and usually forms fluffy, cotton-like structures.

Mycelium in the terrarium, on the other hand, is finer and white. It tends to spread evenly and often combines with organic materials such as leaves or wood. Mycelium is usually a natural part of the decomposition process and is harmless to your terrarium inhabitants.

Tip: If you are unsure whether it is mould or mycelium in the terrarium, pay attention to the consistency and colour. Mould often smells unpleasant, while mycelium tends to remain neutral or smell like fungus. Mould also often grows in small, isolated patches, whereas mycelium is spread over a larger area.

Mycelium in the terrarium as a food source for isopods

Mycelium is an important food source in the terrarium for primary decomposers such as isopods, millipedes and springtails. Woodlice feed on dead plant material that is decomposed by fungi and mycelium. The decomposition process that mycelium sets in motion in the terrarium makes complex organic compounds such as lignin and cellulose digestible for isopods.

But it is not only the decomposed plant remains that are valuable to woodlice – woodlice also eat the mycelium itself. Fungi contain valuable nutrients such as proteins, fats and carbohydrates, which are an important food source for woodlice. Especially in humid environments where fungi thrive, the mycelium is an optimal source of nutrients.

Mycelium also plays a crucial role in the nutrient cycle of the soil by breaking down organic material and releasing nutrients such as nitrogen and phosphorus. These nutrients are in turn absorbed by plants and passed on to the isopods through the food chain. Woodlice help to return these nutrients to the soil through their excretions, which supports the nutrient cycle in the terrarium.

Mycelium also promotes the growth of bacteria and other microorganisms, which are also ingested by isopods. It thus creates a microhabitat that provides a variety of food sources for isopods and contributes to the stability of the terrarium.

Promote mycelium in the terrarium

Instead of fighting mycelium in the terrarium, you can see it as part of the natural cycle. To promote the formation of mycelium, you can use materials such as forest humus, fodder leaves, white rotten wood or flake soil. These provide an excellent food base for fungi and help the mycelium to develop well. A balanced moisture level is also important to support the growth of mycelium without encouraging mould growth.

Conclusion – Mycelium in the terrarium: a useful helper

Mycelium in the terrarium is a natural component of a healthy terrarium and contributes to the decomposition of organic material. It supports the circulation of nutrients and provides many animals, especially isopods, with a valuable source of food. The mycelium in the terrarium should therefore not be seen as a danger, but as an indicator of a functioning mini-ecosystem.

If you are still unsure whether it is mould or mycelium in the terrarium, the tips mentioned above will help you to distinguish between the two. And next time you’re out and about in the forest, take a closer look – you might discover the fascinating network of mycelium there too!

If you have any further questions, please leave them in the comments below the article.