# What is the most numerous free-living species of mammal outside of humans and rats? **URL:** \ **Category:** Factual Questions\ **Created:** [December 8, 2011, 8:27pm UTC](https://boards.straightdope.com/t/what-is-the-most-numerous-free-living-species-of-mammal-outside-of-humans-and-rats/605555 "2011-12-08T20:27:03Z")\ **Posts on this page:** 14\ **Page:** 2
**Author:** ![John\_Mace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_mace/32/185_2.png) [@John\_Mace](https://boards.straightdope.com/u/John_Mace)\ **Post date:** [December 9, 2011, 2:17am UTC](https://boards.straightdope.com/t/what-is-the-most-numerous-free-living-species-of-mammal-outside-of-humans-and-rats/605555/21 "2011-12-09T02:17:46Z")
> [@Stoid](#): > > Correct. > > So the question is probably which rodent? Which bat? I think you had us all confused, otherwise you would’ve gotten brown rat in the first couple posts. No harm, no foul. ---
**Author:** ![Stoid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/stoid/32/272_2.png) [@Stoid](https://boards.straightdope.com/u/Stoid)\ **Post date:** [December 9, 2011, 2:35am UTC](https://boards.straightdope.com/t/what-is-the-most-numerous-free-living-species-of-mammal-outside-of-humans-and-rats/605555/22 "2011-12-09T02:35:29Z")
> [@John\_Mace](#): > > I think you had us all confused, otherwise you would’ve gotten brown rat in the first couple posts. No harm, no foul. Any estimates on numbers? Billions? Yeech. ---
**Author:** ![Namkcalb](https://avatars.discourse-cdn.com/v4/letter/n/c89c15/32.png) [@Namkcalb](https://boards.straightdope.com/u/Namkcalb)\ **Post date:** [December 9, 2011, 2:36am UTC](https://boards.straightdope.com/t/what-is-the-most-numerous-free-living-species-of-mammal-outside-of-humans-and-rats/605555/23 "2011-12-09T02:36:32Z")
The buffalo??? okay, maybe I should stop using my 19th century Children’s encyclopædia. ---
**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\ **Post date:** [December 9, 2011, 3:12am UTC](https://boards.straightdope.com/t/what-is-the-most-numerous-free-living-species-of-mammal-outside-of-humans-and-rats/605555/24 "2011-12-09T03:12:06Z")
> [@Stoid](#): > > The ocean is different, since almost everything in it qualifies as a predator of some kind or another; the ocean has nowhere near enough plant life to support very many vegetarians. [QUOTE=njtt] Unless pelagic animals have learnt how to photosynthesize, this cannot possibly be true. [/QUOTE] The plant life in open oceans, the phytoplankton, is mostly microscopic, that is algae, diatoms, dinoflagellates, etc. There are also huge numbers of photosynthetic cyanobacteria. Most creatures that eat phytoplankton directly are also very small, the zooplankton. It’s true that most of the larger sea life eats animals, but those smaller animals do eat plants or bacteria. ---
**Author:** ![njtt](https://avatars.discourse-cdn.com/v4/letter/n/ecd19e/32.png) [@njtt](https://boards.straightdope.com/u/njtt)\ **Post date:** [December 9, 2011, 3:58am UTC](https://boards.straightdope.com/t/what-is-the-most-numerous-free-living-species-of-mammal-outside-of-humans-and-rats/605555/25 "2011-12-09T03:58:09Z")
> [@John\_Mace](#): > > I think you had us all confused, otherwise you would’ve gotten brown rat in the first couple posts. No harm, no foul. Well, except for the fact that “rat” is explicitly ruled out in the thread title. ---
**Author:** ![John\_Mace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_mace/32/185_2.png) [@John\_Mace](https://boards.straightdope.com/u/John_Mace)\ **Post date:** [December 9, 2011, 4:51am UTC](https://boards.straightdope.com/t/what-is-the-most-numerous-free-living-species-of-mammal-outside-of-humans-and-rats/605555/26 "2011-12-09T04:51:46Z")
> [@njtt](#): > > Well, except for the fact that “rat” is explicitly ruled out in the thread title. Apparently we were not supposed to consider the genus _Rattus_ as one category. Species within the genus are A-OK. ---
**Author:** ![Namkcalb](https://avatars.discourse-cdn.com/v4/letter/n/c89c15/32.png) [@Namkcalb](https://boards.straightdope.com/u/Namkcalb)\ **Post date:** [December 10, 2011, 3:13am UTC](https://boards.straightdope.com/t/what-is-the-most-numerous-free-living-species-of-mammal-outside-of-humans-and-rats/605555/27 "2011-12-10T03:13:34Z")
Sheep are out, the Chinese alone outnumber them. What about rabbits? ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [December 10, 2011, 3:19am UTC](https://boards.straightdope.com/t/what-is-the-most-numerous-free-living-species-of-mammal-outside-of-humans-and-rats/605555/28 "2011-12-10T03:19:22Z")
Did anyone suggest rats? ---
**Author:** ![njtt](https://avatars.discourse-cdn.com/v4/letter/n/ecd19e/32.png) [@njtt](https://boards.straightdope.com/u/njtt)\ **Post date:** [December 10, 2011, 7:29am UTC](https://boards.straightdope.com/t/what-is-the-most-numerous-free-living-species-of-mammal-outside-of-humans-and-rats/605555/29 "2011-12-10T07:29:43Z")
> [@Leo\_Bloom](#): > > Did anyone suggest rats? :dubious: ---
**Author:** ![Darth\_Panda](https://avatars.discourse-cdn.com/v4/letter/d/ee7513/32.png) [@Darth\_Panda](https://boards.straightdope.com/u/Darth_Panda)\ **Post date:** [December 10, 2011, 8:14am UTC](https://boards.straightdope.com/t/what-is-the-most-numerous-free-living-species-of-mammal-outside-of-humans-and-rats/605555/30 "2011-12-10T08:14:07Z")
> [@John\_Mace](#): > > I think you had us all confused, otherwise you would’ve gotten brown rat in the first couple posts. No harm, no foul. Who’s confused now? I see no need to bring birds into this. ---
**Author:** ![Namkcalb](https://avatars.discourse-cdn.com/v4/letter/n/c89c15/32.png) [@Namkcalb](https://boards.straightdope.com/u/Namkcalb)\ **Post date:** [December 10, 2011, 11:05am UTC](https://boards.straightdope.com/t/what-is-the-most-numerous-free-living-species-of-mammal-outside-of-humans-and-rats/605555/31 "2011-12-10T11:05:06Z")
> [@Leo\_Bloom](#): > > Did anyone suggest rats? [I hope these lot get you in your sleep](http://whfb.lexicanum.com/mediawiki/images/4/45/SkavenArmy2.jpg) ---
**Author:** ![TinkerT](https://avatars.discourse-cdn.com/v4/letter/t/b5a626/32.png) [@TinkerT](https://boards.straightdope.com/u/TinkerT)\ **Post date:** [August 13, 2014, 8:22pm UTC](https://boards.straightdope.com/t/what-is-the-most-numerous-free-living-species-of-mammal-outside-of-humans-and-rats/605555/32 "2014-08-13T20:22:19Z")
Killer Whales, Orcas ---
**Author:** ![naita](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/naita/32/5862_2.png) [@naita](https://boards.straightdope.com/u/naita)\ **Post date:** [August 13, 2014, 8:46pm UTC](https://boards.straightdope.com/t/what-is-the-most-numerous-free-living-species-of-mammal-outside-of-humans-and-rats/605555/33 "2014-08-13T20:46:44Z")
> [@TinkerT](#): > > Killer Whales, Orcas You woke a three year old thread to give a completely, bizarrely wrong answer? Not a good first move on a message board dedicated to fighting ignorance. Welcome though. ---
**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\ **Post date:** [August 13, 2014, 10:06pm UTC](https://boards.straightdope.com/t/what-is-the-most-numerous-free-living-species-of-mammal-outside-of-humans-and-rats/605555/34 "2014-08-13T22:06:28Z")
**TinkerT** , we allow old threads to be revived in General Questions in order to provide new information. Since the global population of Orcas is probably well under 100,000, and other species of mammals number in the millions, it clearly is wrong. Therefore I’m going to close this. Colibri General Questions Moderator [Previous page](https://boards.straightdope.com/t/what-is-the-most-numerous-free-living-species-of-mammal-outside-of-humans-and-rats/605555.md?page=1)