# Why is crustacean a group but fish is not?

**URL:** <https://forum.inaturalist.org/t/why-is-crustacean-a-group-but-fish-is-not/76654>\
**Category:** General\
**Created:** [March 15, 2026, 2:39am UTC](https://forum.inaturalist.org/t/why-is-crustacean-a-group-but-fish-is-not/76654 "2026-03-15T02:39:38Z")\
**Posts on this page:** 1\
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**Author:** ![AdamWargon](https://sea2.discourse-cdn.com/flex016/user_avatar/forum.inaturalist.org/adamwargon/32/44649_2.png) [@AdamWargon](https://forum.inaturalist.org/u/AdamWargon)\
**Post date:** [March 16, 2026, 9:47pm UTC](https://forum.inaturalist.org/t/why-is-crustacean-a-group-but-fish-is-not/76654/11 "2026-03-16T21:47:32Z")

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I think Jason put it well. You might not agree with every word, but I think he makes a valid point:  
(I bolded the punchline)

> [@List of paraphyletic groups in iNat's Taxonomy](https://forum.inaturalist.org/t/list-of-paraphyletic-groups-in-inats-taxonomy/19456/10):
>
> Discussions like this could become pretentious if we’re not careful. Birds may be phylogenetically within reptiles, but including them in reptiles would require a lot of changes to our practical definition of reptiles; to the point that it would be nigh impossible to have a useable definition.
> 
> There are already problems on iNaturalist due to the elimination of Class Pisces: sharks and rays which appear as “vertebrates,” because the original observer wanted to ID them as “fishes,” and the only option which has that word in it is “ray-finned fishes.” Someone else then gave the more precise ID, which is not a daughter of ray-finned fishes.
> 
> **Phylogenetic pedantry only makes nature even less accessible to laypersons, which is the opposite of iNaturalist’s purpose.**

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