Fungi are heterotrophs, meaning they obtain their energy by consuming organic matter. They do not produce their own food through photosynthesis like plants do.

Here's a breakdown of the energy sources fungi use:

* Sugars: Fungi primarily break down complex carbohydrates like cellulose, starch, and sugars into simpler sugars for energy. They achieve this through extracellular digestion, releasing enzymes that break down food outside their cells.

* Other organic matter: Fungi can also consume a wide range of organic materials, including:

* Dead plant and animal matter: This is a key role they play in decomposition, recycling nutrients back into the ecosystem.

* Living organisms: Some fungi are parasitic, feeding on living plants or animals.

* Waste products: Fungi can also break down waste products like sewage and industrial byproducts.

In summary: Fungi use the energy stored in organic matter that they consume, breaking it down into usable sugars through extracellular digestion.