I found here that species-wise it is cow. But, collectively, insects may exceed even mammals. So, which class of animals constitutes the largest biomass?

  • $\begingroup$ Prokaryotes still rule the world. Bacterial and Archaeal biomass far exceeds any other class of living organism. $\endgroup$
    – AMR
    Commented Oct 26, 2015 at 8:58
  • 2
    $\begingroup$ But prokaryotes are no animals. $\endgroup$
    – ChrKoenig
    Commented Oct 26, 2015 at 9:28
  • $\begingroup$ according ot this, arthropods. weforum.org/agenda/2021/08/total-biomass-weight-species-earth the big kicker is krill, there is a LOT of rill in the ocean. $\endgroup$
    – John
    Commented Sep 13, 2023 at 22:42

1 Answer 1


Following from MarchHo's comment, I have not been able to find class-specific (in the formal sense) estimates, but if you meant 'class' in an informal sense, the following may be useful.

A nice infographic covering the relative biomass of all land mammals is here, and a full table for species groups (at the level of domesticated vertebrates, invertebrates, etc) is here (reproduced below).

enter image description here

Short answer: amongst animals, invertebrates are where the mass is.

  • $\begingroup$ Don't invertebrates make up multiple phyla and not a single class though? $\endgroup$
    – March Ho
    Commented Oct 26, 2015 at 13:50
  • $\begingroup$ @MarchHo Good point. I read the question as 'group' in the informal sense, but that was based on the comments mentioning Kingdom-level groups, rather than the question itself. $\endgroup$
    – bshane
    Commented Oct 26, 2015 at 14:29

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