Love forests? Thank fungus!

At first glance, the mushrooms we see popping up on the forest floor may appear pretty insignificant. They’re lovely, sure, but most are small and rubbery, and they disappear pretty quickly during dry periods.

As it happens though, these little nubbins are crucial to our forests’ very SURVIVAL. How is this possible? Let’s dig a bit deeper. There are thousands of mushroom species, which are part of the Kingdom Fungi. Most live in the soil or on other living things like trees, and they feed mainly on dead matter. Unlike animals, they digest food outside their bodies, using chemicals to break down their meal before consuming it.

Trees and mushrooms help each other. Guess what else they have in common? A fruit to plant ratio!

Yes, some cause disease, but there are so many more helpful mushrooms than harmful ones. Our debt to our fungal friends goes back hundreds of millions of years, when life first started moving out of the oceans and onto land. Plants could not have made that leap without mushrooms first creeping onto the rocks and digesting them into nutrients (i.e. plant food, like phosphorus or magnesium). This allowed plants to move in, dry off, and, over millions of years, diversify into the incredible environments we enjoy today.

There are two main ways that forests STILL depend on mushrooms:

1. Mushrooms decompose dead things. Think of all the leaves that fall and the plants and animals that die in the forest every year. Without decomposers, they would just lie there, eventually piling up enough to smother the forest itself. Luckily, fungi break it all down to nutrients that get recycled back into the forest system, supporting new life. Other critters like worms and beetles decompose dead things too, but — not to play favourites or anything — mushrooms do it the best.
2. Many mushrooms actually feed trees. That seems strange- what could fleshy little mushrooms have to offer towering trees? Here’s the thing: the mushrooms we see are only the reproductive bits attached to the main fungal body — called mycelium — which can be ENORMOUS! They’re similar to apples in this way, they make up just a small part of the entire apple tree.

The mycelium stays mostly out of sight — underground or inside trees — and is made up of thin, quickly-growing strands that look a bit like cobwebs. They can squeeze their way into the tiniest underground nooks and crannies, and are about 100 times better at getting water and nutrients from the soil than are the relatively shorter, stubbier tree roots.

So mushrooms gather water and nutrients for trees and deliver them right to their roots. Why so helpful? Trees give something back! Through photosynthesis, plants take carbon from the atmosphere to make carbohydrates (i.e. sugar), the main building block of plants. Most trees make extra: they give sugar to mushrooms, and mushrooms give water and nutrients to trees — a sweet deal!

These tree-fungal relationships are called mycorrhizae, and they benefit the vast majority of trees and other plants. Often neither the tree nor the mushroom could survive without the other! In harsher environments (like, let’s face it, Canada’s), forests really depend on mushrooms to stay healthy.

And who depends on forests? We all do! For clean air, biodiversity, climate regulation, food, lumber, and medicines to name a few. One thing that’s very clear — we have a lot to thank mushrooms for!

Who Knew What Grew on Poo?

A large colony of Pilobolus, also called the
Hat Thrower or Dung Cannon 

I don’t want to offend anyone’s delicate sensibilities (or maybe I do!), but this post is about poo. More specifically, it’s about a secret world that grows on poo, a secret world than can be fascinating and sometimes—of all things!—strikingly beautiful.

This Eyelash Cup (Cheilymenia stercorea) grew on deer droppings.

I'm talking about coprophilous, or dung-loving, fungi. These fungi are our friends, as are all decomposers. They help dispose of what we don't want to see, breaking it down until it's nutritious compost—for the forest floor, the field, the garden. 

Some coprophiles are big. A few, like portobello and button mushrooms are good edibles (you did know that they're grown on a pasteurized substrate that contains manure, didn't you?). But most are so tiny you need a magnifying glass to see them. These are the guys I'm interested in.

This deer pellet has three species growing on it. The tiny white
ones  grew into the smallest gilled mushrooms I've ever seen.

Right now, in fact, I'm trying to grow some of these mini characters on what used to be our dining-room table. 

About a week ago I was given a few samples of dried animal dung that are older than I am. At one time, these bits of dung had been studied, and then dried and stored, because interesting little fungi had been growing on them. The question is, are the spores that this dung holds still viable? Will fresh fungi appear? I have a bit of cow, goat, deer and rabbit dung, each now rehydrated and sitting in a moist chamber. Not much is happening yet, but I have high hopes.

The wee black cones at the top of this rabbit pellet are a kind of Podospora.

These samples I'm nursing originally grew either nondescript lumps called Sporormiella (a Latin genus that when spoken aloud makes you sound drunk) or cuter ones from the genus Podostroma. I found some Podostroma a couple of years ago on a rabbit pellet. Though it's not the prettiest fungus, it has very nifty black spores that sport see-through tails.

A Podospora spore—with see-through tails at both ends!

The Royal Ontario Museum's fungarium has an immense collection of fungi, over half a million, a large proportion of which are dung-lovers, because one of the early directors of the collection, Roy F. Cain, was a world-renowned dung-loving fungi lover. But what's to love about about these lowly characters? 

I found this amazing furry Phycomyces fungus on raccoon scat.

Well, besides some being pretty, many have adapted to their chosen dung homes in downright astonishing ways.

My favourite is Pilobolus, also known as the hat-thrower or cannon fungus. These sparkling jewels don't look very fungal. Each has a skinny stem that rises only a few millimetres above the cow patty or horse puck it grows on. At the top of the stem there's a bulbous, transparent, fluid-filled "head," a head that wears a black "hat." Clustered beneath the hat are its spores.

Close up of the Hat Thrower or Dung Cannon

So how do the spores of these fungi get into the dung in the first place? They're ingested by the animal. And no, horses and cows don't eat poo. In fact, they shun it just like you do. Pilobolus's brilliant solution to this problem is to blast their spores away from the poo they grow on—up to two metres away. Recent research has determined that their spore-carrying "hats" can reach a speed of 25 metres a second. But the most amazing part is the acceleration, which is the greatest of any living thing! Pretty impressive for something that's less than a millimetre in diameter.

Pilobolus head & spore capsule "hat" under the microscope

When I squashed it under a slide cover, the spores were released.

Not only do these little guys shoot their spore capsules a distance away, they're capable of aiming with the help of a light sensor inside their stems. On top of that, they also have a sticky coating on the exterior of their black "hats" that makes them stick to nearby plants, where they cling at the perfect height to be eaten by a passing quarter horse or Holstein. 

The black dots are Pilobolus spore capsules or "hats" that stuck to
the wall of the plastic container I put the horse dung in. 

How can you not love dung-loving fungi when there are characters like this around?

If you'd like to read more about Pilobolus and other fascinating fungi, (including a couple of other dung-lovers—Eyelash Cups on Moose and Deer Droppings and A Poop and Scoop Cup Fungus), check out my fungi blog, Weird & Wonderful Wild Mushrooms.

A Tribute to Scavengers and Decomposers

by Jan Thornhill

I visited a school a few days ago to talk about my books and, as usual, passed around the contents of my “museum-in-a-bag,” a collection of, among other things, skulls, dinosaur bones, desiccated insects, snake skins, feathers, and a mummified bat and two hummingbirds. The children are always very careful with my treasures, but that day my white-tailed deer skull finally snapped in half. I wasn’t exactly surprised, since this particular skull has been handled by at least 5,000 kids over the past few years. Besides, I can always glue it back together again. I’d like to save it, though, because, like many of the things in my bag, the deer skull has a story.

White-tailed deer skeleton (Jan Thornhill)

I found it, along with most of the rest of the deer’s skeleton behind a fence on my road. It’s not hard to imagine how the animal died: I’m sure someone struck it by accident with their car. Though mortally injured, it must have managed to make two great bounds, one to get off the road and the other to get over the fence. The person who hit it must have been relieved to see it disappear into the brush as he or she drove away. But then, alone, the deer collapsed and died.

A year earlier, I had looked for puffballs in exactly the same spot in late autumn. There were no deer remains then, so the longest it could have been hidden there was twelve months. Amazingly, other than a few wisps of hair and a couple of snippets of dried skin, the skeleton was completely clean – clean enough that I had no qualms about bringing it home.

So who do I have to thank for cleaning those bones for me? Scavengers and decomposers, that’s who – my favorite characters in the food chain.

I was quite sure a coyote must have visited the corpse of the deer shortly after it died since the bones of two of its legs were missing. The coyote is the only animal in my neighborhood that is strong enough to drag away such large parts. Though they’re predators, and often hunt for food, coyotes are also such frequent scavengers that they’ve developed a special receptor in their brains that makes them immediately throw up anything that is dangerously rotten. So a coyote wouldn’t have had to feed on the carcass immediately, especially if the deer had died in the cold of winter.

Coyote feeding on elk carcass (Courtesy Bryan Harry, U.S. Fish & Wildlife Service)

Turkey vulture

Other scavenging mammals, such as foxes and skunks, might also have visited the corpse, as well as birds, such as crows and vultures. Our local turkey vulture is one of the few large animals that is a dedicated scavenger, which means that its only food is carrion, or already dead or decaying flesh. They’re perfect for this job: they have an extremely well-developed sense of smell that allows them to home in on food that's miles away; their bald heads reduce the amount of rotting matter that might stick to them; strong acids in their digestive tracts destroy harmful bacteria; and their urine is also very acidic – and here’s the best part – so they pee down their legs to let the acid destroy nasty bacteria clinging to them. 

As well as being fed upon by these larger animals, in the warmer months corpses attract an amazing number of insects. A variety of flies are lured by the smell of death and lay their eggs. Their larvae, or maggots, are voracious carrion feeders. Flesh-eating beetle larvae continue the job and, later, other beetles with specialized mouth parts show up to feast on tough skin and ligaments, followed by moths that eat fur and hair. These insects all arrive at such specific stages of decomposition that forensic entomologists, scientists who study the insects that are found on or near dead things, can use their knowledge of this progression to determine the time of death when the remains of a human are found.

Close-up of a blowfly maggot (Eye of Science)

Throughout this whole process bacteria are active, gobbling up the corpse from within. These bacteria produce gases as a waste product, and it’s these gases that are responsible for the putrid odors that waft off rotting animals. Humans are naturally revolted by these smells, which is a good thing. If we weren’t disgusted by the smell of decomposition, we might be tempted to eat food that has gone bad and get sick from the bacteria growing on it. Interestingly, almost everyone in the world says the same thing when confronted by these smells, some version of “Yuck!” or “Ick!” This verbal gagging is so natural and so universal that some people think it might be the way that human language began.

My tip to anyone who finds an animal skull (or other bones) and wants to bring it home, is to use your eyes and nose. If it looks gross and smells disgusting, leave it where it is. Mark the location and return in a few months. More often than not, scavengers and decomposers will have completely cleaned it up for you.

You can find out lots more about death and decomposition in my book: I Found a Dead Bird: The Kids’ Guide to the Cycle of Life & Death (Maple Tree Press)

Here’s a fun, time-lapse video showing a watermelon decomposing over 35 days: http://thekidshouldseethis.com/post/12926682492