Fish is a paraphyletic grade that gave rise to tetrapods. Crustacean is a paraphyletic grade that gave rise to hexapods. These are analogous situations. Yet inaturalist treats crustacean as an official group and not fish. Why? I cannot see any utility in keeping crustacea together that doesn’t appl…

Because Catalogue of Life is the taxon authority for animal subphyla and includes Crustacea but not Pisces. It’s worth noting that from my understanding paraphyly of Crustacea is a much more recent discovery, with its wide acceptance probably post-dating the founding of iNat by several years. I als…

I believe the same happened with birds being dinosaurs being reptiles. While all three are listed as classes, all three are part of the reptiles. The same reason was given, however I don’t see why dinosaurs couldn’t at the very least be moved to the reptiles

@yongestation is correct. At this point, the iNaturalist database is so large it is virtually impossible to move around any high level taxa, sometimes even down to family. @loarie has said that they are looking into addressing this, but it will “not be addressed for a while.” iNaturalist is not inte…

Some of that is discussed here: https://forum.inaturalist.org/t/list-of-paraphyletic-groups-in-inats-taxonomy/19456

This reminds me of my favorite podcast, No Such Thing As A Fish by the people that write for QI.

Honestly if they are gonna keep Reptilia and Crustacea they should have kept Pisces too.

why? if a new user wants to browse fish observations they can find 95% of them under Actinopterygii, which is the first thing that comes up if you type “fish” into the search bar. i think it’d be nice if all the clades were monophylectic, but i do seriously see a downside in the new user experience…

IMO, given that genetic studies are showing phylogenies we previously could never have imagined (maybe we will eventually know if ctenophora or porifera are truly the most basal animals, and where placozoa go!) I think the ideal solution would be to have a truly monophylitic tree with support for pa…

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) [image] List of paraphyletic groups in iNat's Taxonomy Discussions like this could become pretentious if we’re not careful. Birds may be phylogenetically within reptiles,…

Why is crustacean a group but fish is not?

General

upupa-epops March 16, 2026, 9:41pm 10

I made a Fish project which includes fishes and doesn’t include not-fishes: https://www.inaturalist.org/projects/these-are-fishes

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Why is crustacean a group but fish is not?

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