This year, as you may have noticed, has been one long party in honor of Charles Darwin. That’s now drawing to a close. But don’t put away your glad rags. Next year is also slated to be one long party; this time, in honor of biodiversity. Yes, 2010 is to be an international knees-up for the other species on the planet.

MBARI/From “The Deep,” University Of Chicago Press Ping-Pong tree sponge, from the Monterey Bay’s floor.

It’s not clear to me what, in practice, this celebration is going to mean. But the prospect of it has led me to get out some picture books — books like “The Deep,” which is full of incredible photographs of strange beings. For example: Chondrocladia lampadiglobus, the ping-pong tree sponge, which lives more than a mile and a half below the surface of the sea. This creature looks more like a piece of modern art than an animal: it has an array of spherical, translucent globes on stalks that join together at the center. It looks harmless, decorative even. But it’s a carnivore. Shrimps or other critters that settle on it quickly become stuck; the sponge then consumes them.

Or — this book is one of my favorites — “Identification Guide to the Ant Genera of the World,” which consists of hugely magnified images of the faces of ants, both head-on and in profile. I’ve never identified an ant with it; but I love looking at the astonishing variety that we, in our bigness, don’t usually get to see. Some of the faces are smooth; others have whorls and ridges. Some ants have unobtrusive mouth parts; others have great scythes. With this book in hand, there’s no need to invent monsters: you just need to imagine how terrifying it would be if ants were the size of rhinos.

Looking through these books, it’s hard not to be struck by the immensity of the planet — it’s home to all these life forms! And we haven’t even met them all yet. Just this past August, a paper published in Science announced the discovery of a new group of deep-sea swimming worms that release green fluorescent “bombs” when they are attacked. (The bombs are balls of fluid; they don’t turn green until the animal releases them.)

We’ve been making discoveries on land, too. Indeed, since 1993, more than 400 new species of mammal have been described — and this is a group that’s been studied well. And it’s not because we’ve identified lots of new mice or bats. The discoveries include an antelope, the saola, that weighs more than 100 kilograms (220 pounds); a sloth that lives on an island off Panama; several new species of monkey; and a squirrel-like animal that appears to be a living representative of a group thought to have gone extinct around 11 million years ago.

Mulling all this over, a number of thoughts run through my mind.

The first is that we still don’t know the planet all that well. On the one hand, this is exciting: there’s so much more to learn! Millions of new species may await discovery; and discovery is only the first step. Once an organism has been identified, we can learn about its lifestyle: its mating habits (if any), what it eats, how long it lives, what weird genetic quirks it has and so on.

On the other hand, our lack of knowledge is a bit worrying. Although we often behave as if we’re the only ones who live here, we depend on other organisms in all manner of ways. Some of these are obvious. We hunt fish to eat them; we grow cows for meat, milk and leather. We cultivate silkworms to make clothes. We grow a large number of plants for diverse purposes — to eat, or to use as drugs, timber or paper.

But much of our dependence is less obvious. Worms, fungi, insects and microbes consume dead bodies and fallen branches. Some organisms consume dung; others move seeds. Many organisms make soil richer and more fertile. Plants around streams and rivers filter the water and make it cleaner. Plants also take carbon dioxide from the air, and thus affect the composition of the atmosphere; their roots help prevent soils from washing away. Some bacteria may play a role in making clouds; the list goes on.

By and large, we do not pay for any of this: our economics does not, for the most part, include paying for nature.

But we pay when it is lost. Less fertile soils make it harder to grow crops. Dirtier water is more expensive to make fit for human consumption. The collapse of fisheries leads to unemployment. The loss of mangroves increases the impact of tsunamis. The loss of animal species increases the risk that humans will catch diseases such as Lyme disease. Again, the list goes on.

The other beings that live here with us are, like us, descended from ancient lineages. In and of themselves, they are marvels to be wondered at. But they are also precious: they make our planet what it is today. Still, as the great American environmentalist Aldo Leopold once said, when something vanishes, “We grieve only for what we know. The erasure of Silphium from western Dane County is no cause for grief if one knows it only as a name in a botany book.” Yes: if we don’t know something, we don’t care if it goes.

This, then, is what the International Year of Biodiversity should be about: it should be about conveying the excitement of discovery in biology, coupled with an intimate knowledge of the majesty of nature. For we must start cherishing our fellow life forms, and treating them well: we need them, in more ways than we probably imagine. Their loss makes the planet — and ourselves — poorer.

So please be up-standing, raise your glasses and join me in a toast to: “Other Life Forms!”

And let’s make sure that in the years ahead, we don’t need to change it to “Absent Friends.”

Notes:

Many thanks to Dan Haydon for insights, comments and suggestions.

Editor’s note: In an earlier version of this piece, “saola” was misspelled; it has been corrected.