What single species' extinction would do the most damage to Earth?

Not a species, but a group of animals - the spiders. Imagine mosquitoes and disease spreading flies with no control. Hello, Malaria!

There’s a type of beetle that eats cattle dung; without it, it just accumulates and accumulates ( that happened once to an island that lacked the beetle, until it was imported ).

Plankton, that would then wipe out most sea creatures and plenty of land animals.

Sitnam’s suggestion was what was going through my mind when I read the OP. Yes – plankton, krill, the start of the marine food chain that affects so many other creatures further up the line, including ourselves.

The dodo bird.

We must protect this species at all costs. Once it’s gone, we’re all doomed.

My first thought was the ocean algae that generates so much of the oxygen we enjoy on a daily basis. I don’t know if there’s a single key species, though.

We could still use a clarification of the OP (or at least, I could).

A statement was made in the new TED video – can’t remember who by – saying, “If all insects disappeared tomorrow, homo sapiens would be extinct in 50 years, but if homo sapiens disappeared, life would flourish.”

True, but there are many species of plankton IIRC. For a single species to do much damage to humans by vanishing, I bet it would have to human specific, like e coli as mentioned.

And just what is this globally distributed unique cow-poo eating beetle? I’ve seen all sorts of beasts eating cow dung, up to and including spaniels. Cow flops are the pretty much the hamburgers of the detritivore world - not necessarily that healthy or filling, but always popular with the crowds.

Yeah. Just what do you call a beetle that eats dung?

My vote goes with Krill or Kelp - both are pretty crucial to the health of the oceans. We just don’t know how much impact it would have - but it would be worldwide, not just on one or two continents.

(We would probably be better off, ecologically, in North America if the earthworm didn’t get brought here 400 years ago.)

Why?

I did not know that. I can now go to bed a little less ignorant than I woke up. Thank you Fetchund, that’s another CecilPoint to your score.

Ringo?

Humans, of course. Think of all the starving rats, mice, cockroaches, yorkshire terriers, shetland ponies and chickens we’d leave behind! Not to mention all the food crops that would go extinct.

My vote goes to the Bees (Anthophila) in general. But it would have to be all 20,000 species.
My second vote is, as stated by others above, krill or plankton.

Whatever. :rolleyes:

There are redundancies built into our ecology, my dear JThunder. If anything were to happen to the dodo, the passenger pigeon could easily step into its place.

Too late.

Yep, I was thinking cows. Man I love me some beef. Chickens also crossed my mind, but there are enough chicken and egg substitutes that I don’t think it would be all that big a deal. Extermination of the cows would IMO wreak the most havoc with humanity.

I think that if plankton were wiped out, that would wreak the most havoc on the Earth. Plankton is at the bottom of the oceanic food chain, and most of the ocean’s fauna depend on it in some form, either 1st, 2nd, 3rd degree, etc.

If I were the malignant entity, I wouldn’t take away a species, I’d speed up the proliferation of the already proliferating coliform taxifolia.