Fungi are so different from plants and animals that scientists
have placed them in their own kingdom. It wasn't always so.
Until the 1700s, biologists thought fungi were plants. Only
when the microscope was invented were they able to reveal important
differences.
We seldom see most of the living parts of a fungus. They lie
concealed beneath the surface of its substrate—the soil,
a tree, a loaf of bread, or an orange. All fungi—moulds,
yeasts, mushrooms, and relatives—are masses of fine, branching
threads or tubes, called hyphae (singular: hypha) spreading
outwards in their quest for food.
The whole diffuse mass of hyphae is called a thallus or mycelium
(plural: thalli, mycelia). Unlike a plant or animal, the body
of a fungus is not divided into tissues or organs such as leaves,
roots, or a nervous system .
Like plants, fungi have bodies composed of cells. But unlike
plants, they lack chlorophyll, the molecule used in photosynthesis
to produce sugars with the help of sunlight. Instead fungi feed
themselves in an animal-like way. They utilize plant and other
organic matter by releasing a variety of powerful enzymes into
their surroundings. Enzymes break complex organic matter into
simpler water soluble compounds. The fungi then absorb these
smaller molecules into their cell and use them to grow.
Another major difference between plants and fungi is the composition
of their cell walls. Cellulose is the material that adds firmness
to the walls of plant cells. Fungi toughen theirs with chitin,
the material that also forms the exoskeletons of insects, crabs,
and lobsters. |
