In March 2015 I was one of the PhD candidates at Wageningen University chosen to give a pitch talk on the topic of Fascinating Nature in honour of the 97th Dies Natalis of the university. Here is a transcript of what I said (or at least had prepared to say)
In a hole in the ground, there lived an earthworm...
“In a hole in the ground, there lived a hobbit”. So begins a famous story about a small and humble-looking creature that lives underground and accomplishes big things. My story to you today is similar in many ways: it’s also about small creatures that live underground and can do something big. Not hobbits, but... earthworms.
I know that sometimes, when I tell people I study earthworms, some of them react in what I would not describe as a positive way. And I can understand that, because earthworms don’t look particularly fascinating. They are slimy, hermaphroditic, and you know... worm-like. They’re not the epitome of cool. But they can do something momentous. If I had to say it in one sentence, I’d say that earthworms make soil more alive.
And that’s a word I’d like to stress, alive; because whenever you walk in a forest or on a field, the soil under your feet is teeming with life. Its functioning, its fertility depend on that life. But, like any living thing, soil can also die. And we are killing it, actually. Through climate change, deforestation and so forth we are eroding soil, consuming it faster than it can reform. And by using too much fertilizer in agriculture we are making it addicted to our inputs, less able to function naturally. So we need to study life in soil, both to understand nature, and improve our relationship with it. And this is why I want to tell you about earthworms, one of the main players in the game of soil.
So, what do earthworms do? Well, first of all we could even say that they make soil, in a way. They mix it, transform it, shape. So large is their influence that ecologists have called them the “ecosystem engineers”. And it’s actually an apt title: there are species that make vertical tunnels in soil that can be two meters deep, and make soil better at absorbing water. That’s quite an engineering solution, I’d say. Then they contribute to soil fertility, by helping with decomposition: the recycling of organic matter and energy that is as essential to life as the production of that energy in the first place – which is, by the way, a lesson that our economy should learn from nature, I’d say. And different earthworms contribute to decomposition in different ways. Those that make vertical tunnels take organic material from the surface, like plant leaves, and take it inside their tunnels, when it gets decomposed faster. There are then many other earthworms that you may never see in your life, because they don’t come at the surface, they live underground for most of their life; and they dig in soil all the time, and they do it by eating it. They eat soil – lot of soil. Next time you walk on a grass field, or in our beautiful campus, think that all that soil under your feet, the first let’s say 30 centimetres, in a few years’ time will pass through earthworm guts. And when they come out, they are more fertile: everything else being equal, plants grow about 20% bigger in a soil with earthworms than in one without.
As you would expect, of course this has a big impact also on the other life forms that occur in soil (or, as one of my supervisors would say, are part of soil). And there are many of these life forms, most of which are actually unknown to most people. There are animal groups, like Paurododa and Symphyla, that even most biologists have never heard about. And we know a lot more about this fascinating world now that when this university was founded, but we keep finding surprises. I’ll make an example. Only last year, a collaborator of mine found that some soil amoebae, which are single-celled organisms, can eat nematodes. Now, nematodes are tiny, tiny worms, much smaller than earthworms, they’re microscopic – but to an amoeba they are quite huge. And yet some amoebae, it was found, can hunt them, because they hunt in packs. Imagine lions hunting elephants on a microscopic scale, and the lions are single cells!
So there is clearly much more beauty and drama right under our feet than we often realise. And ultimately this is why I study earthworms. Yes, they are important to soil fertility, they are important to agriculture, but besides all this, and besides what they look like, I think they are cool. Thank you.
I know that sometimes, when I tell people I study earthworms, some of them react in what I would not describe as a positive way. And I can understand that, because earthworms don’t look particularly fascinating. They are slimy, hermaphroditic, and you know... worm-like. They’re not the epitome of cool. But they can do something momentous. If I had to say it in one sentence, I’d say that earthworms make soil more alive.
And that’s a word I’d like to stress, alive; because whenever you walk in a forest or on a field, the soil under your feet is teeming with life. Its functioning, its fertility depend on that life. But, like any living thing, soil can also die. And we are killing it, actually. Through climate change, deforestation and so forth we are eroding soil, consuming it faster than it can reform. And by using too much fertilizer in agriculture we are making it addicted to our inputs, less able to function naturally. So we need to study life in soil, both to understand nature, and improve our relationship with it. And this is why I want to tell you about earthworms, one of the main players in the game of soil.
So, what do earthworms do? Well, first of all we could even say that they make soil, in a way. They mix it, transform it, shape. So large is their influence that ecologists have called them the “ecosystem engineers”. And it’s actually an apt title: there are species that make vertical tunnels in soil that can be two meters deep, and make soil better at absorbing water. That’s quite an engineering solution, I’d say. Then they contribute to soil fertility, by helping with decomposition: the recycling of organic matter and energy that is as essential to life as the production of that energy in the first place – which is, by the way, a lesson that our economy should learn from nature, I’d say. And different earthworms contribute to decomposition in different ways. Those that make vertical tunnels take organic material from the surface, like plant leaves, and take it inside their tunnels, when it gets decomposed faster. There are then many other earthworms that you may never see in your life, because they don’t come at the surface, they live underground for most of their life; and they dig in soil all the time, and they do it by eating it. They eat soil – lot of soil. Next time you walk on a grass field, or in our beautiful campus, think that all that soil under your feet, the first let’s say 30 centimetres, in a few years’ time will pass through earthworm guts. And when they come out, they are more fertile: everything else being equal, plants grow about 20% bigger in a soil with earthworms than in one without.
As you would expect, of course this has a big impact also on the other life forms that occur in soil (or, as one of my supervisors would say, are part of soil). And there are many of these life forms, most of which are actually unknown to most people. There are animal groups, like Paurododa and Symphyla, that even most biologists have never heard about. And we know a lot more about this fascinating world now that when this university was founded, but we keep finding surprises. I’ll make an example. Only last year, a collaborator of mine found that some soil amoebae, which are single-celled organisms, can eat nematodes. Now, nematodes are tiny, tiny worms, much smaller than earthworms, they’re microscopic – but to an amoeba they are quite huge. And yet some amoebae, it was found, can hunt them, because they hunt in packs. Imagine lions hunting elephants on a microscopic scale, and the lions are single cells!
So there is clearly much more beauty and drama right under our feet than we often realise. And ultimately this is why I study earthworms. Yes, they are important to soil fertility, they are important to agriculture, but besides all this, and besides what they look like, I think they are cool. Thank you.