Any answer you get is going to have about as many caveats as the number of species. Basically, no one knows. The actually scientifically classified species and genera only represent a small part of the actual ones in existence. It might seem that when you step up to the family classification or above, that things would get simpler, but unfortunately, it only gets more complex at that level with mass changes on practically a daily basis. We haven't come close to counting the number of species, and are barely even getting started on trying to understand their relationships to each other.

Here are some quick google results that might shed some light on your question:

The estimated number of animals on our planet falls somewhere in the vast range of 3-30 million species (Erwin 1983, Wolosz 1988). (see link below)

The National Science FoundationÂs "Tree of Life" project estimates that there could be anywhere from 5 million to 100 million species on the planet, but science has only identified about 2 million. (Life Science, http://www.livescience.com/strangenews/070803_gm_numberspecies.html )

Here is a link that might be useful: How Many (Animal) Species Inhabit Our Planet

thanks for your response. do you think i would have more success if i narrowed my question to--how many orders, families and genera are there in the cronquist classification system?
what puzzles me further is that i can go to a genus and learn how many species there are or go to a family and determine how many genera there are in it but no answer for how many overall families, orders or genera there are.i'm only interested in plants not animals. how about some good old fashioned guessing? anyone?

Based on what I have on hand I would guess about 150 orders of plants. Families and genera are going to be considerably higher. Someone who has access to a complete database would be able to give a pretty accurate number in a minimal amount of time. I don't have access to such a database though.

"How many (known and generally accepted) orders, families, and genera (of angiosperms) are there in the Cronquist classification system?"

If you limit your search to that degree, Wikipedia reports,"The (Cronquist) system, as laid out in An Integrated System of Classification of Flowering Plants (1981), counts 321 families and 64 orders."

Though of course Cronquist is very out-of-date and not much used any more . . .

Resin

Hi
Only family I even remotely keep up with is orchids and last I heard they still are the most diverse most lists say around 30,000 specie 2000 natural hybrids. 60,000 man made
with over 200 man made genus. While I recently heard of 150 new species within the last 5 years no new genus.
Of couse if your reading is over a week old you'll find somebody somewhere revising everything all over again lol.
can't imagine actually counting animal species .I'd bet money plants will prove impossible even if you stick to flowering plants alone. gary

my final estimate is:

orders: 100 +/-
families: 400 +/_
genera: 15,000 +/-
species: 250,000 +/-

would love to hear an opposing view.

Hi
Can't help with the question but was wondering about classification of deep sea life forms or those (Plants?)
found growing in crystals?? bacteria growing in volcanoes.
Seemingly defying all the accepted norms of what makes life possible at all.??
Imagine the chaos if life forms are discovered that are not carbon based?? If (When?) life is discovered on another planet can't imagine what it will do to the naming system lol.??. I can't even keep up with the NEW words being generated by ( What is a planet or a ballpark on how many there are ??.lol Oh well will bump your post up. I'm curious as to the answers myself gary

Gillmass, if you are still around,

Somehow I missed your "final estimate" post back when this thread was current. I notice (even without the study I will mention later) that your data is far, far below even the cataloged numbers! I hope your post wasn't part of a school paper or something, because I bet the results would not have been good.

Anyway, I saw an interesting paper the other day on this subject and thought I'd post a link. According to a new study, which seems to have quite a bit of support, the total number of species on Earth is predicted to be around 8.75 million. The paper is linked below.

Here is a link that might be useful: How Many Species....

can't imagine actually counting animal species

& no one wants to even think about the domains outside of Eukaryota (Bacteria & Archaea). You can't even get a count on "kingdoms" in those.

The problem is that modern taxonomy is based on systems and models that are several centuries old. There are attempts to address the issues (via cladistics & molecular phylogenies) but there's a lot of resistance, especially from the public.

In a cladistic taxonomy, you don't have genera, families, orders, etc. Everything is a clade, with smaller clades within larger clades. It doesn't sound like a huge difference, but it is. It also matches what we see in nature better.

"That way lies madness, and cladistics. But I repeat myself" - James Valentine, "On The Origin of Phyla"