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What is a Fungus?

Mary McMahon
Mary McMahon
Mary McMahon
Mary McMahon

A fungus is an organism in the kingdom Fungi. Fungi are extremely interesting organisms, sharing traits with both plants and animals which made them difficult for early scientists to classify. Originally, fungi were treated as plants, but this classification was found inadequate as people learned more about them, leading people to realize eventually that fungi really needed their own kingdom.

With over 80,000 known species within the fungus kingdom, it's hard to make sweeping generalizations about fungi. Several features characterize a fungus, however, including the lack of chlorophyll and vascular tissue. The lack of chlorophyll means that fungi cannot photosynthesize like plants do, while the lack of vascular tissue restricts the nutrients which a fungus can access, and the complexity it can achieve.

Moldy bread.
Moldy bread.

Fungi feed on organic material, secreting enzymes to break down material so that nutrients will be released in a way which allows the fungus to absorb them. Fungi can reproduce sexually and asexually in an assortment of ways, with some species sending out spores, while others asexually bud to produce clones of themselves. Along the way, many fungi help to break down leaf litter and other organic material, contributing to the slow cycle of recycling which keeps nature in balance.

An antifungal cream.
An antifungal cream.

Mushrooms, molds, smuts, yeasts, and lichens are all classified in the fungus kingdom. These organisms are incredibly diverse. Lichens, for example, form symbiotic living arrangements with bacteria, using the bacteria as an energy source. Yeasts can range from Candida, the yeast which causes thrush, to Saccharomyces cerevisiae, the yeast used by bakers to make bread. Molds like black mold can pose a threat to human health when they colonize structures, while smuts colonize plants such as corn, developing a parasitic relationship which humans can sometimes use to their advantage.

Mushrooms.
Mushrooms.

Fungi range from single-celled organisms to massive colonies of honey fungus which can cover impressive swaths of land. There are seven phyla in the fungus kingdom, each of which has distinctive defining characteristics. You might be familiar with representatives of several phyla: culinary mushrooms, for example, tend to belong to the Basidiomycota phylum, while many disease-causing yeasts, along with penicillin, come from the Ascomycota or “sac fungus” phylum.

Shiitake mushrooms, a fungus, have the scientific name Lentinula edodes.
Shiitake mushrooms, a fungus, have the scientific name Lentinula edodes.

Some fungi happen to be edible, with an occasional species being quite delicious. Others are incredibly toxic. Fungi can be used medicinally in a range of ways, and they can also pose medical problems when they colonize the human body. Fungi are also everywhere, from the air you breathe to the ground you walk on, and new species are always being uncovered.

Frequently Asked Questions

What exactly is a fungus and how does it differ from plants and animals?

Oyster mushrooms.
Oyster mushrooms.

Fungi are a distinct kingdom of organisms that differ from plants and animals in several ways. Unlike plants, fungi lack chlorophyll and cannot photosynthesize; instead, they absorb nutrients from their environment. They also differ from animals, which ingest food, because fungi secrete enzymes to break down organic matter externally before absorption. Fungi have a unique cell wall composition, primarily made of chitin, not found in plants or animals.

How do fungi reproduce, and what are spores?

Lichen is part of the fungus kingdom despite having a symbiotic relationship with bacteria.
Lichen is part of the fungus kingdom despite having a symbiotic relationship with bacteria.

Fungi reproduce through spores, which are microscopic particles that can be spread by wind, water, or living carriers. These spores can remain dormant until conditions are favorable, at which point they germinate and grow into new fungal organisms. Fungi can reproduce both sexually and asexually, with some species capable of producing millions of spores to ensure their survival and propagation.

What role do fungi play in the ecosystem?

Mushrooms are a type of fungus.
Mushrooms are a type of fungus.

Fungi are crucial to ecosystems as decomposers, breaking down dead organic matter and recycling nutrients back into the soil. They form symbiotic relationships with plants through mycorrhizal associations, enhancing plant nutrient uptake. Fungi also contribute to the creation of soils, support plant health, and are involved in various food webs, impacting the survival of many other organisms.

Can fungi be harmful to humans or the environment?

While many fungi are beneficial, some can be harmful to humans and the environment. Pathogenic fungi can cause diseases in plants, animals, and humans, such as athlete's foot or crop blights. Invasive fungal species can disrupt local ecosystems by outcompeting native species. However, the vast majority of fungi are not harmful and play essential roles in ecological balance.

What are some common uses of fungi in industry and medicine?

Fungi have numerous industrial and medicinal applications. The antibiotic penicillin, derived from the fungus Penicillium, revolutionized medicine. Fungi are used in the production of food and beverages, like bread, beer, and cheese. They are also employed in biotechnology, for example in the production of enzymes for detergents, and in bioremediation processes to clean up environmental contaminants.

How does climate change affect fungal populations and diversity?

Climate change can significantly impact fungal populations and diversity. Changes in temperature and moisture levels can alter fungal growth patterns and distribution. Some species may thrive under new conditions, while others may decline or become extinct, potentially disrupting ecosystem functions. Fungi's role in carbon cycling also means they can both influence and be affected by climate change dynamics.

Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a AllThingsNature researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

Learn more...
Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a AllThingsNature researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

Learn more...

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    • Moldy bread.
      Moldy bread.
    • An antifungal cream.
      By: picsfive
      An antifungal cream.
    • Mushrooms.
      By: Aaron Amat
      Mushrooms.
    • Shiitake mushrooms, a fungus, have the scientific name Lentinula edodes.
      By: Chris leachman
      Shiitake mushrooms, a fungus, have the scientific name Lentinula edodes.
    • Oyster mushrooms.
      By: Africa Studio
      Oyster mushrooms.
    • Lichen is part of the fungus kingdom despite having a symbiotic relationship with bacteria.
      By: alessandrozocc
      Lichen is part of the fungus kingdom despite having a symbiotic relationship with bacteria.
    • Mushrooms are a type of fungus.
      By: Konstanze Gruber
      Mushrooms are a type of fungus.