A Grisly Meal

"Feed Me" by Renee Silverman. Image licensed under creative commons.

“Feed Me” by Renee Silverman. Image licensed under creative commons by Flickr.com.

From grizzlies to wolves to the people-eating plant in The Little Shop of Horrors, carnivores capture our imaginations, and sometimes send shivers down our spines. So, imagine my astonishment and wonder when I recently learned that below the ground, at a microscopic scale, there are fungi that hunt and eat live animals. Fungi. Hunting. This astounding news took my understanding of the weirdness and wildness of fungal diversity to new heights.

I knew that some fungi kill our plant crops, such as the wheat rust that Ben described in his post last month. I also knew that some fungi are top-tier recyclers that break down 85 billion tons of carbon each year as they transform dead material into soil and food for their growing bodies. But I had never heard that some fungi snare, trap, and devour nematodes, amoebas, and bacteria in the soil. Images of a microscopic fungal safari began to flit through my mind, prompting me to spread the word—in classes, at dinner parties, and while blogging.

A fungus of the genus Arthrobotrys, showing adhesive nets which it uses to trap nematodes. Numbered ticks are 122 µm apart. "20100828 005957 Fungus" by Bob Blaylock. Image licensed under creative commons by wikipedia.com.

A fungus of the genus Arthrobotrys, showing adhesive nets which it uses to trap nematodes. 
“20100828 005957 Fungus” by Bob Blaylock. Image licensed under creative commons by wikipedia.com.

One such story starts with the large fungal spore of Arthrobotrys anchonia, our first creature-in-profile. Fungal spores are minute reproductive structures that help spread the relatively immobile creatures across the land. This particular spore is packed with enough energy to sprout a hypha, a root-shaped structure that is the main body of the fungus. As the hypha develops, it also grows circular, pressure-sensitive snares. Once these traps are set, the fungus waits, living on stored energy until a nematode inadvertently wanders into one of the rings. As soon as the snare senses a touch, the triggered cells rapidly expand and the loop tightens around the nematode. Fungi don’t have mouths, so the fungus penetrates and grows into the nematode’s body to consume the meal. This first food is critical to the life of the fungus; if it doesn’t capture prey before it uses up its stored energy, it withers and dies.

“Oyster Mushroom” photograph by Aaron Sherman. Image licensed under creative commons by wikipedia.com.

“Oyster Mushroom” photograph by Aaron Sherman. Image licensed under creative commons by wikipedia.com.

Even the more familiar oyster mushroom, Pleurotus ostreatus, is a well-equipped hunter. The fungus’ hyphae exude droplets of a paralyzing toxin into the soil. When nematodes unwittingly bump into these stupefying droplets, the fungus grows into the immobile prey and digests the quarry. Bacteria suffer a similar fate when they encounter this deadly trapper.

Fungi never cease to amaze. So next time life seems mundane, investigate one of these mysterious creatures. Scientists estimate that only 10% of all fungal species have been described. It is truly a frontier waiting to be explored.

Emma Stuhl is a second-year student in the Field Naturalist Program. Much thanks to Terry Delaney’s Plant Pathology course for inspiration and species information.

Mushrooms in our Midst

They rose up from the ground like golden fingers, grasping the earth of the Northern White Cedar Swamp. Once aware of their presence, I began seeing their relatives everywhere. Black tongues sprouting from stumps, miniature sheets of rolling parchment across a log, raisin-like swellings on branches, delicate feathers and elegant goblets along fallen trees, a smear of blue paint on a stick, a white parasol shading decaying leaves.

How are they alike? They are all mushrooms. Around this time of year, especially after rain, you see them bursting forth from the leaf litter and colonizing fallen logs.

Golden Spindle (Clavulinopsis fusiformis)

Golden Spindle (Clavulinopsis fusiformis)

Mushrooms are the fruiting bodies present in some fungi—like the apples of a tree. The fruiting bodies contain spores that produce new fungi, similar to the seeds in fruit. The rest of the fungus, called the mycelium, is often underground.  It’s made up of a network of fine filaments, also known as hyphae. These filaments resemble the roots of plants, but unlike roots, hyphae actively digest their surroundings. The mycelium portion of fungus can be massive.

Turkey Tail (Trametes versicolor)

Turkey Tail (Trametes versicolor)

In a single cubic inch of soil, there can be more than eight miles of these cells – around 300 miles of mycelium to a footprint. In fact, the largest living organism is a fungus – a single individual that has colonized an area roughly 2,400 acres in eastern Oregon. That’s 1,665 football fields. Fungi are also powerful; the mushrooms of one fungus, Coprinus comatus, develops with such ferocity that it has been known to break through asphalt. Another fungus, Pilobolus, blasts its spores at a force of 20,000g—more than double the acceleration of a bullet from a vintage rifle.

Crowded Parchment (Stereum rameale)`

Crowded Parchment (Stereum rameale)`

Fungi aren’t plants – they’re actually more closely related to animals as their cell walls have chitin (a tough substance also found in the exoskeletons of insects and crustaceans). Fungi are decomposers, breaking down plant tissue and other materials. However, many fungi get an extra boost of nutrition through a symbiotic relationship with a host plant. In exchange for a renewable food source, the fungi provide mineral nutrients and water taken up by their incredible surface area. 95% of examined plants obtain nutrients and water through a relationship with fungi. Some fungi are saprophytic, feeding on dead or decaying organic matter in the soil and making room for new growth. Some are parasitic, feeding off of living tissue.

Humans have appreciated mushrooms throughout history. A 5,300 year-old Tyrolean Ice Man, Otzi, was discovered frozen in ice with a satchel of Tinder polypore (Fomes fomentarius), along with Birch polypore (Piptopurus betulinus). Perhaps they were used as a fire starter, or maybe for its antibacterial properties, or possibly to ward off insects or evil spirits.

Black-footed Polypore (Polyporus badius)

Black-footed Polypore (Polyporus badius)

Today, fungi have a wide range of uses– decomposable packaging, insect extermination, antibiotic production, and contaminant mitigation. In addition, mushroom burial suits have been developed to facilitate the process of human decomposition while cleansing the body of accumulated toxins

Even if you don’t want to be buried with a suit embroidered with spores, there are plenty ways to appreciate fungi. Go out this autumn and relish the myriad of mushroom forms. Contemplate the vastness of mycelium under your feet and how it supports the life growing over your head.

Ellen is a first year student in the Field Naturalist Program. 

A Chicken of the Woods

ChickenOfTheWoodsBy Colin Stone Peacock

I am the glistening, blackened, and charred non-stick remains of a foodie. Enameled by years of cooking and eating professionally, I am unphased by the most ample and esoteric culinary ingredients and pathologies.

But the bitter kimchi of my heart sweetened ever so slightly the summer before last, when I met the bright and gleaming orange and yellow folds of Laetiporus sulphureus, commonly known as Chicken of the Woods.

It is one of the most easily identifiable, seasonally available, and tastiest mushrooms I have ever met. The drab and fickle morels of my forefathers will never look the same. Chicken is the flavor I would use to describe them. That, and a citric tanginess I have never encountered in another fungi. Continue reading