The Mysterious Kingdom of Fungi: Neither Plant Nor Animal

Beneath your feet as you walk through a forest, stretching in vast networks through the soil, lies an organism that might be thousands of years old and weigh hundreds of tons—yet remains largely invisible to the human eye. Welcome to the mysterious kingdom of fungi, a realm of life so distinct that scientists had to create an entirely separate biological kingdom to classify these peculiar organisms.

Neither plant nor animal, fungi represent one of nature's most successful evolutionary experiments. From the mushrooms we eat to the yeasts that give us bread and beer, from the molds that produce life-saving antibiotics to the pathogens that threaten global food security, fungi have shaped human civilization in profound ways while remaining enigmatic and frequently misunderstood.

The Hidden Giants Beneath Our Feet

When most people think of fungi, they picture mushrooms—the familiar caps and stems that appear after rain. But these visible structures represent only a tiny fraction of the organism, equivalent to the fruit on a tree. The true body of a fungus is the mycelium, a vast network of microscopic threads called hyphae that spread through soil, wood, or whatever substrate the fungus inhabits.

The Largest Living Organisms on Earth

In Oregon's Blue Mountains lies what many biologists consider the largest living organism on Earth—a honey fungus (Armillaria ostoyae) that spans 2.4 miles (3.8 km) across, covering an area equivalent to 1,665 football fields. Scientists estimate it has been growing for somewhere between 2,400 and 8,650 years.

To put this in perspective, when this fungus was first establishing itself:

• The Egyptian pyramids might not yet have been built

• Humans were just beginning to develop agriculture in some parts of the world

• Much of North America was still covered by glaciers from the last ice age

Even more remarkably, this isn't an unusual case. In Michigan, scientists discovered another fungus covering 37 acres with an estimated weight of 100 tons—making it heavier than a blue whale.

The Underground Internet

Perhaps even more fascinating than their size is how fungi function. Mycologist Paul Stamets describes mycelium as "Earth's natural Internet," and the comparison is surprisingly apt:

• Mycelial networks transmit information and resources between plants

• They connect trees of different species in cooperative networks

• They can sense and respond to damage in distant parts of their network

• They transfer carbon, nitrogen, and other nutrients between plants based on need

This "Wood Wide Web," as it's sometimes called, fundamentally changes our understanding of forest ecosystems. Rather than individual plants competing for resources, forests increasingly appear to function as superorganisms, with fungi facilitating communication and resource sharing between plants.

The Third Kingdom: Neither Plant Nor Animal

Fungi were once classified as plants, but this fundamental misunderstanding has been corrected by modern science. Fungi are actually more closely related to animals than to plants, having diverged from animals approximately 1.5 billion years ago.

More Like Animals Than Plants

Unlike plants, fungi:

• Cannot produce their own food through photosynthesis

• Have cell walls made of chitin (the same material as insect exoskeletons) rather than cellulose

• Absorb nutrients from their environment rather than producing them

• Do not contain chlorophyll or chloroplasts

But unlike animals, fungi:

• Grow throughout their lives rather than developing to a predetermined size

• Digest food externally by secreting enzymes and then absorbing the nutrients

• Reproduce through spores rather than embryonic development

This unique biological position allows fungi to perform ecological roles that neither plants nor animals can fulfill.

Nature's Recyclers: The Decomposition Specialists

Fungi possess a remarkable superpower that's essential to life on Earth: they can decompose lignin, one of the main components of wood and one of nature's most stubborn materials.

Breaking the Unbreakable

Without fungi, Earth would be buried under mountains of dead trees and plants. A fallen log in a forest might take centuries to decompose through physical and bacterial processes alone. With fungi present, that same log can be broken down in as little as 3-5 years.

This decomposition ability stems from fungi's unique enzymes:

• Lignin peroxidase breaks down the tough lignin in wood

• Cellulase enzymes digest cellulose in plant cell walls

• Proteases break down proteins in dead animals

These enzymatic capabilities make fungi Earth's primary recyclers, releasing carbon, nitrogen, and other elements locked in dead organisms back into the ecosystem where they can be used by living organisms.

Cleaning Nature's Messes

This decomposition talent doesn't stop with natural materials. Some fungi can break down:

• Petroleum products and oil spills

• Plastic polymers

• Explosive compounds like TNT

• Pesticides and other toxic chemicals

Mycoremediation—the use of fungi to clean environmental contaminants—represents one of the most promising sustainable approaches to environmental cleanup. Experiments using oyster mushrooms have successfully broken down diesel oil in contaminated soil, reducing it by 95% in just 16 weeks.

The Fungal Pharmacy: Medicine from Mushrooms

Long before humans understood what fungi were, we were harnessing their medicinal properties. Traditional Chinese and Japanese medicine have used medicinal mushrooms for thousands of years, while indigenous cultures worldwide have incorporated fungi into their healing practices.

The Antibiotic Revolution

The most famous fungal contribution to medicine came in 1928 when Alexander Fleming discovered that the mold Penicillium notatum produced a substance that killed bacteria. This discovery of penicillin transformed human medicine, providing the first effective treatment for bacterial infections that had plagued humanity throughout history.

Today, numerous antibiotics come from fungi, including:

• Cephalosporins from Acremonium species

• Griseofulvin from Penicillium griseofulvum

• Cyclosporine from Tolypocladium inflatum

Beyond Antibiotics

Modern research into medicinal mushrooms has identified numerous compounds with potential health benefits:

• Turkey tail mushrooms (Trametes versicolor) contain polysaccharide-K (PSK), used as an adjunct cancer treatment in Japan

• Lion's mane mushrooms (Hericium erinaceus) contain compounds that may stimulate nerve growth and protect against dementia

• Cordyceps mushrooms have been shown to increase exercise performance and oxygen utilization

• Reishi mushrooms (Ganoderma lucidum) contain compounds with immunomodulatory and anti-inflammatory properties

While research continues to determine the efficacy of these treatments, the fungal kingdom clearly remains a promising frontier for new drug discovery.

Fungi and Human Civilization: A 9,000-Year Partnership

Our relationship with fungi extends beyond medicine into the very foundations of human civilization. Archaeological evidence suggests humans have been intentionally using fungi for at least 9,000 years.

The Fermentation Revolution

Yeasts—single-celled fungi—made agriculture vastly more valuable by enabling fermentation. This process not only created new foods and beverages but also helped preserve nutrition through winter months when fresh food was scarce.

Some historians argue that the desire for reliable beer production may have been a primary driver for the development of agriculture and settled communities—making fungi partially responsible for the transition from hunter-gatherer societies to civilization.

Psychedelic Pioneers

Some of the most fascinating fungal influences on human culture come from psychoactive species. There's compelling evidence that psychedelic mushrooms containing psilocybin influenced religious practices across multiple ancient civilizations:

• Mushroom stones and art from Mesoamerican cultures date back over 3,000 years

• Cave paintings in North Africa and Spain depict what appear to be mushroom rituals

• Some scholars suggest the mysterious "soma" described in ancient Vedic texts was a mushroom preparation

Today, after decades of prohibition, psilocybin mushrooms are being studied for therapeutic applications, showing promising results for treatment-resistant depression, end-of-life anxiety, and addiction.

The Masters of Survival

Fungi have colonized virtually every habitat on Earth, from the deepest ocean trenches to the frozen Antarctic, from desert sands to nuclear disaster sites.

Radiation Eaters

Perhaps the most dramatic example of fungal resilience comes from the Chernobyl Nuclear Power Plant. Following the 1986 disaster, scientists discovered several fungal species actually growing toward the radiation source inside the damaged reactor.

These radiotrophic fungi contain melanin—the same pigment that gives human skin its color—which appears to allow them to convert radiation into chemical energy through a process similar to photosynthesis. Some of these fungi have been sent to the International Space Station as potential radiation protection for astronauts.

Desert Survivors

In the world's harshest deserts, certain fungi form partnerships with cyanobacteria and algae to create biological soil crusts. These living soil layers retain moisture, prevent erosion, and fix nitrogen in environments where most life cannot survive.

Some desert truffles can remain dormant for years during drought conditions, only to fruit abundantly when rare rains arrive—sometimes producing over 100 pounds of truffles per acre after a good rain.

Cold Specialists

In Antarctica's Taylor Dry Valley—one of the coldest, driest places on Earth—researchers discovered fungi living inside rocks. These endolithic fungi create microenvironments that capture enough moisture and nutrients to survive in conditions that kill almost all other life forms.

Meanwhile, snow molds grow happily under winter snowpack at temperatures just above freezing, while other fungi thrive in refrigerators and freezers.

The Dark Side: Fungal Threats to Ecosystems and Health

Despite their many benefits, fungi also present significant challenges to human health, agriculture, and wildlife conservation.

The Silent Killers

Several emerging fungal pathogens threaten entire species:

• Chytrid fungus has driven over 200 amphibian species to extinction or near-extinction

• White-nose syndrome has killed millions of bats across North America

• Dutch elm disease has decimated elm populations across Europe and North America

• Sudden oak death continues to transform forest ecosystems on the West Coast

These pathogens often spread through human activities like global trade and travel, introducing fungi to new environments where host species have no evolutionary defenses.

The Coming Fungal Threat

Climate change may be setting the stage for new fungal threats to human health. Most fungi cannot infect humans because our body temperature is too high for them to thrive. However, as global temperatures rise, fungi are gradually adapting to higher temperatures.

Simultaneously, ongoing antibiotic overuse has created resistant bacterial infections, pushing medicine to rely more heavily on antifungal medications. This increased exposure is accelerating fungal adaptation to our defenses. Medical mycologists warn this combination could lead to serious new fungal diseases in humans within our lifetime.

The Fungal Frontier: New Discoveries and Technologies

Despite thousands of years of human interaction with fungi, we've only scratched the surface of this biological kingdom. Scientists estimate there may be between 2.2 and 3.8 million fungal species, but we've identified only about 120,000—roughly 3-5% of the total.

Building with Fungi

Innovative companies are developing sustainable materials using mycelium:

• Packaging materials that replace Styrofoam

• Building insulation with better performance than fiberglass

• Furniture and structural materials stronger than some woods

• Leather alternatives for fashion and upholstery

• Burial containers that decompose and enrich the soil

These materials require far less energy to produce than conventional alternatives and decompose naturally at the end of their useful life.

Fungal Computing

Perhaps the most surprising frontier is using fungi for computation. Researchers have demonstrated that slime molds (once classified as fungi though now considered protists) can solve complex optimization problems like finding the shortest path through a maze or designing efficient railway systems.

More recently, scientists have created mycelium-based "living circuits" that can process logical operations similar to electronic computers, but using biochemical signals instead of electricity. While still in early research stages, these "living computers" could someday lead to biological sensing systems that adapt to their environments.

Becoming a Fungi Fan: Connecting with the Fungal Kingdom

You don't need to be a mycologist to develop a deeper appreciation for fungi. Here are several ways to connect with this fascinating kingdom:

Mushroom Foraging

Mushroom hunting is an engaging way to learn about fungi while connecting with nature. Important tips for beginners:

• Always go with an experienced guide

• Never eat anything you cannot identify with 100% certainty

• Use regional field guides specific to your area

• Join a local mycological society for group forays and expert identification help

Mushroom Cultivation

Growing your own mushrooms is easier than you might think:

• Oyster mushrooms will fruit on used coffee grounds or straw

• Shiitake and wine cap mushrooms can be grown on logs in shady yards

• Indoor grow kits require minimal space and maintenance

The experience of watching mushrooms develop—sometimes growing visibly by the hour—provides a unique window into fungal biology.

Fungal Photography

The incredible diversity of fungal forms, colors, and habitats makes them compelling photography subjects. Macro photography particularly reveals the intricate gill structures and surprising textures invisible to the naked eye.

Conclusion: Reimagining Our Relationship with Fungi

As we face global challenges like climate change, pollution, and resource depletion, fungi offer remarkable lessons and opportunities. These ancient organisms demonstrate nature's principles of recycling, interconnection, and adaptation with unparalleled success.

The more we learn about fungi, the more it becomes clear that they aren't just interesting biological curiosities—they're essential partners for humanity's sustainable future. From cleaning pollution to creating new materials, from healing ecosystems to potentially healing our bodies, fungi represent one of our most powerful allies.

The next time you notice a mushroom pushing up through the soil or spot a bracket fungus on a tree trunk, take a moment to appreciate what you're seeing—not just an interesting organism, but a representative of an entire kingdom of life that has been recycling, connecting, and healing our planet for over a billion years.

In the words of mycologist Paul Stamets: "Mushrooms are not only the guardians of the forest but the guardians of our future." Perhaps it's time we paid more attention to nature's quiet recyclers and gave them the appreciation their billion-year success story deserves.