Species are being wiped out so fast that scientists say humanity may be triggering the sixth mass extinction in history. How much does it matter and what should we do?
Should pandas be saved before nematodes?
Should we protect all species or just the ones that are useful? Can we demand that the world's poor to stop exploiting the ecosystems they survive on?
As decision-makers gather to discuss the race to protect species at the Cites conference in Bangkok, BBC News Online looks at opinions from different sides of the debate.
Professor John Lawton, Natural Environment Research Council
Callum Rankine, Species Officer, WWF.
Animals do not exist for our benefit. They exist because they evolved to do a certain job within nature. But if a species does not benefit people directly, they often don't see a reason to conserve it.
We at WWF are looking at it from an ecological point of view: All species are doing a job, even if we don't know what that job is.
Removing a species from the ecosystem is like removing a rivet from an aeroplane without knowing its function. Nobody would want to fly in that aeroplane - but that is what we are doing to our environment. We are causing species to go extinct left right and centre without knowing what they do.
As far as we know, this is the only planet we can live on. We are stuck here and we are mucking about with our life support system. That doesn't strike me as sensible.
Ian Parker, author and game hunter.
As many life forms are harmful to human well-being, it is downright silly to say we should preserve the world's biodiversity in toto.
We want to exterminate Aids viruses, bacteria that cause tuberculosis, malaria plasmodia that kill millions of children annually, and countless other harmful pathogens. So it is, too, with black rats and locusts.
Our welfare relates directly to eliminating harmful forms of life and we are unavoidably committed to modifying our environments to suit our particular needs.
Common sense calls for accepting that in many cases, this means exterminating some of its elements.
The challenge conservationists face is to keep them as few as possible, and avoiding dogmatic and palpably insupportable claims that all must be preserved.
Henrik Saxe, Environmental Assessment Institute.
If we want to conserve every species on Earth starting with bacteria and virus and ending with the African elephant, we are saying that humans should not inhabit this Planet.
Civilisation comes with a price. And few of us would do without the comfort of modern life.
When we chose to preserve nature - and we should - we have to prioritise how much we will spend, and how to spend it to preserve the most biodiversity.
This takes knowing the greatest threats (agriculture, forest clearing, toxic pollution, climate change, etc), and putting our money where it works. As we see it at the Environmental Assessment Institute, it is all about prioritisation.
Dr Jon Hutton, Chair of the Sustainable Use Specialist Group, IUCN.
One way to make conservation gains is to capitalise on the importance of wild species in human livelihoods - and paradoxically the sustainable harvesting of plants and hunting of animals has often turned out be a highly effective conservation measure.
When we think of biodiversity we tend to think of the obvious elements - all the species of animals and plants that we can see and identify around us.
Should we conserve lions? Most people would say we yes, but people in Africa are happy to see the back of them if it means their children can walk to school in safety.
Conservation is a difficult business, involving tough decisions and trade-offs. Ultimately it hinges on the goodwill of the people who live with the "biodiversity" being conserved.
Professor John Lawton, Natural Environment Research Council.
Beyond mammals, birds and plants, we remain remarkably ignorant of how many species there are on the planet - let alone how many are disappearing.
Even for those plants and animals that we do know about, we understand little about their distribution, ecology or population size.
Our knowledge is most limited for the very geographic areas where the diversity of life is greatest - principally in the tropics. And very little is known of the deep sea.
The charismatic mega-fauna aside, I'd like to see much more research going into things smaller than a millimetre.
If I had my time again, I'd look at nematodes, soil micro-organisms and creepy crawlies. They are the unsung heroes of the natural world, and we know next to nothing about them.
Send us your views:
The earth is such an intricate place with incredibly complex cycles of chemicals that the mass human ignorance, to me, seems incredible. Most still don't realise that every new extinction is a step toward our own. We are born from nature and are part of it, therefore it is ridiculous that our societies drive us to live and believe ourselves to be so far apart from it. Advanced civilisation?! We are not supreme beings merely obscenely arrogant and all life forms are of equal importance. We cannot survive without most of the things that we are so busy destroying. It just seems logical to me that every form of life on this planet has its intrinsic place and requires protection from the ignorant humans.
Laura Blaker, Eastbourne, UK
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