The rumen is the first gut chamber of certain animals called ruminants. Ruminants use microorganisms to ferment and otherwise partially digest cellulose-bearing vegetable matter. Ruminants include cattle, dear, giraffes, antelopes, goats, sheep but also some marsupials. The microorganisms include fungi, bacteria, archaea, ciliates and more.

There’are something like 4 billion ruminants in the world (4 × 10^9), and it is estimated that a litre of rumen fluid contains a quadrillion organisms (10^15).

Obviously the size of the rumen varies greatly by species but the single biggest category of ruminant by headcount is the dairy cow, which has a rumen about 175 L in capacity.

The rumen world population, then, is something in the general vicinity of 700000000000000000000000000, or 7 × 10^26. This could be expressed as 700 septillion, or seven hundred million billion billion.

I wonder how many rumen biotas were there when there were animals of mass migration and mammoths and aurochs and such.

You know just what to say before I even ask.

sarahs mum said:

I wonder how many rumen biotas were there when there were animals of mass migration and mammoths and aurochs and such.

I wouldn’t be surprised if it turns out that we are now at the highest rumen population count ever, given the number of dairy cows. Mammoths were big but there weren’t a billion of them.

dv said:

sarahs mum said:

I wonder how many rumen biotas were there when there were animals of mass migration and mammoths and aurochs and such.

I wouldn’t be surprised if it turns out that we are now at the highest rumen population count ever, given the number of dairy cows. Mammoths were big but there weren’t a billion of them.

And ruminants burp methane a lot, seriously adding to ruminantogenic global warming.

dv said:

sarahs mum said:

I wonder how many rumen biotas were there when there were animals of mass migration and mammoths and aurochs and such.

I wouldn’t be surprised if it turns out that we are now at the highest rumen population count ever, given the number of dairy cows. Mammoths were big but there weren’t a billion of them.

Agree. Not much survived the ice ages.