There could also be far fewer plants and animals left for them to find

We've already found more than a million species, but unearthing the rest was thought to be an impossible task.

But now it seems an army of amateur scientists have taken up the cause. A new study concludes that, thanks to them, we're in a golden age of discovery, with 20,000 new finds charted each year.

There could also be far fewer plants and animals left for them to find. The researchers say rather than tens of millions of species living on Earth, there could be between two and eight million.

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I think “for them to find” is a complement for “left,”
and “left for them to find” is a complement for “plants and animals.”
and “plants and animals” is a complement for “far fewer,”
and “far fewer plants and animals” is a complement for “could also be.”
Is this right?