Fungi absorb nutrients from plant or animal matter around them, which may be living or dead. They produce long, slender threads called hyphae that spread through their food. The hyphae release enzymes that break down the food into substances that the fungi can easily absorb.

Most fungi reproduce by releasing tiny spores that then germinate (sprout) and grow into a new fungus. The spores are produced by, and released from, a fruiting body that is visible above the ground. Some fungi drop spores, which are blown away by the wind. Others shoot them out in an explosive burst.

Toadstools are brightly colored and poisonous to eat, but mushrooms are usually edible and dull in color. Both toadstools and mushrooms are fruiting bodies (spore-bearing structures) produced by fungi. They belong to the same group, the Basidiomycetes, so scientists make no distinction between the two.

The bright red color of these fly agaric toadstool caps warns animals that they are poisonous. The caps, which are supported by stalks, produce spores. These spores are released from downward-hanging plates, or gills.

Scientists are continually revising the classification of the fungi kingdom (with more than 100,000 species), but currently they divide it into three groups:

Fungi called molds produce the woolly or furry growths found on rotting foods, such as bread and fruit. The growths are formed by threadlike hyphae that grow upward and release spores from their tips. These spores then sprout on other foods.

Pin molds grow on starchy foods, such as bread, in a mass of gray hyphae with black tips that release spores. The spores float to other pieces of bread. Unseen here are hyphae growing into the bread and absorbing its nutrients.