I was reading a previous post about the potential problems occurring from a severe decline in the population of bees and huge ramifications it would have on human beings. That got me thinking, what other animals are out there performing functions necessary for human life as we know it which cannot be replaced by artificial means at this time?
Well, losing pigs, chickens, cows and sheep would be quite a big blow. I’m sure we’d find alternatives, but it would be a big deal even to lose one major domestic farm species like that.
My suggestion would be bacteria. Especially those involved in the decomposition of organic material. ( I just read a cool book called “The Ghost Map”.)
Anyway, that’s my submission.
But maybe you were asking about larger animals that could actually face extinction, in which case I got nuthin’.
Life as I know it requires bread and beer, so I nominate yeast.
Yeast is not an animal. Neither are bacteria.
Mitochondria.
Wait, I guess they’re out, too. 
Correct.
It seems that bacteria reproduce asexually by eithe “budding” or 'fission".
So they do not qualify as animals.
Submission withdrawn.
I could see losing the large mammals without too much of a problem. People have shown that humans can live on a vegan diet… whether or not that’s a life worth living is debatable.
What about insects though? If every insect on the planet was to disappear tomorrow would plant life be affected in enough ways that our oxygen supply would be threatened?
If every insect disappeared, it would be a very big deal - certainly causing massive food chain disruption including lots of extinctions. Some humans would probably survive, but the ecosystem of our planet would be vastly altered.
However, ‘insects’ is a really large diverse group - I get the impression the OP was looking for species or at least smaller, more distinct groups.
Some animals can reproduce that way. I think bacteria are excluded by phylogeny, not morphology.
Check out Dust by Charles Pellegrino for an interesting idea on what would happen if all the insects went extinct. (He has a lot of other ecological weirdness going on at the same time, too.)
I’d nominate earthworms. As I understand it, many food crops would be at best difficult to grow if these little critters weren’t terraforming the soil.
I think that of all living things in this world (bacteria, fungi, plants, animals, etc), losing animals would have the least impact on our lives and of the whole ecosystem deal. Let alone one specific species.
I nominate cows tho. As least for here in America. At the very least, if every cow were to suddenly die, there would be widespread panic. I don’t think that would be the case with certain insects.
Believe it or not, bats. At least they would have enormous ramifications for SOME populations and I suspect that could end up reaching farther than one might think. There are some islands (Puerto Rico, for one) in which the bats come out at night, pollinate numerous necessary plants and control the insect population.
Without them, plants would die, insects would take over and chaos would ensue, snowball style.
Additionally, the danger of losing entire bat populations is very real. For one thing, people fear them unnecessarily and don’t like seeing them out and about doing their business at dusk (they tend to flock out when the sun sets, creating a scene much like a volcano). For another, it’s VERY easy to wipe out the entire population of an island or other area, just by “bombing” one cave. Toss in whatever poison is necessary while they’re all hanging there and voila…end of the pollinators and insectivores.
And, you know…end of the local crops (now eaten by bugs, unpollinated, etc.).
I dunno. According to the latest issue of National Geographic, there were no earthworms in the Americas before the Europeans landed, yet the Indians had developed an awesome array of agricultural products.
I don’t know about Terraforming, seems to me the Earth has already been terraformed.
Aerating, maybe, which is a good thing.
The complete loss of any animal, ecologically speaking, would create some sort of domino effect, which would, in turn, cause problems in those populations. In North America, I’d go with either the bovine or possibly some sort of predator bird species.
If we lost cows, we’d see both positive and negative effects. Negative in that we have no more beef to eat, positive in the amount of pasture land and especially WATER we’d save.
IS there an online cite for that?
Actually, now that I’ve read ALL the posts, I’m going to agree with bats. They are a very important species.
With all the furor lately I’m surprised nobody has mentioned bees.