Many of you have seen my previous post where I compared the sampling completeness for 126 arthropods on inaturalist. I want to give further perspective by comparing them to all the vertebrate orders too.
As you can see, tetrapods and especially birds are highly complete, such that they appear as a straight line. Fish on the other hand are kind of intermediate between tetrapods and arthropods.
Just like with the analysis of arthropods alone, the species richness of orders has almost no correlation with their completeness on inat, except for ones with less than 10 species. Birds are all super complete for example. And even fish with wildly varying numbers of species seem to have similar levels of completeness.
And here is for number of observations. What is up with these birders??? Birds never stay still, and they never let you get close to them. How is there so many observations?
What are your guys thoughts? Could fish reach bird or mammal levels of completeness? Will we see an unexpected myriapod revolution?
Why not? Fish, in spite of their difficulties, are far better observed than any class of arthropods. How often are new fish species discovered (not counting taxonomic revisions)? Part of the problem with arthropods is that bajillions of new species are being discovered and the inat observations canāt keep up with it. While not quite on the same level as mammals or birds, it seems a majority of fish species have been genuinely discovered, and certainly they are much closer to approaching complete discovery than crustaceans, myriapods, arachnids or insects (note, I am just speaking of how many species are discovered then observed on inat, not how many times each species is observed which is a whole different story)
A lot of places fish live are pretty much inaccessible to humans without extremely specialized equipment. In the deep sea new fish are discovered regularly, albeit at a low frequency. And we donāt really have a good handle on what the actual diversity is in some of the colder oceans either, especially under ice shelves.
Birds are pretty easy, all things considered, all you need is a bit of money and time. Birding is one of the most popular nature based activities for retirees and people getting into nature, and people travel widely in search of birds to add to their life-lists.
New birds are still ādiscoveredā, but those are often splits of already observed species.
When comparing completeness and number of observations, most insect orders seem to be on a similar magnitude to fish orders. Fish on the one hand are easier to identify to species level and have fewer species, but are often highly inaccessible. Insects are much more common and accessible, but are way harder to id to species level and have way more species. So it balances out.
Then you have crustaceans, which have the drawbacks of both fish and insects with the benefits of neither. Imagine the small size, identification difficulty, and high species count of insects combined with the inaccessibility of fish. Yeahā¦
Insects are kind of a different thing altogether. We havenāt fully identified all the species, let alone observed them. With wasps and beetles alone we have only named a fraction of the total number of estimated species.
A bunch of insect species need highly detailed microscope photos, or high magnification macro photos, to even properly identify them.
Looking at iNat observations and IDs of insects gives a somewhat biased view as what has been identified in the scientific literature is not at all representative of the total number of estimated species, so our actual IDās are a much lower percentage than what iNat data would suggest.
Haha how is birding so surprising to you? Birds are the easiest group to observe - and in particularly to record for iNat, because itās pretty easy to get photos that are good enough for ID - and you can also just record sounds.
How difficult is species id for fish? Can they be reliably narrowed to species by photographs of living individuals?
As for insects having unknown diversity, i assume this must apply to crustaceans as well. So the overall point stands. Like i said, crustaceans have the drawbacks of both fish and insects and the benefitts of neither.
Can you reliably ID the grasshoppers by the sounds? May be actually worth doing if thatās the case! Probably not here in Europe, where there isnāt that many species, so Iād get photos of all eventually, but maybe somewhere in the tropics? But then maybe the cacophony is too much?
Itās still a pretty small part of insects though. I think that for many ābirds are easy because they Xā, you are gonna find a group of insects for which thatās true, but the difference is how universally easy the birds are, except for a small hard subset.
It varies widely depending on what kind of fish it is - many medium to large coral reef fishes are easily identified off colouration and pattern, even with distant views, but others, like small gobies and various small cypriniforms, may require very close-up photos with the fins spread to use fin ray counts for identification.
I would imagine the hardest bird order to complete would be Passeriformes - if only due to the sheer number of species placed in this order (approximately half of all extant birds!!). It would be easy to rack up a large number of species in this order, but actually completing it would require finding hundreds of species that are exceedingly rare, occur only in a tiny range, are highly cryptic, or any combination of those.
It is probably something this obscure. I have never seen anything from that order myself, I donāt even know off the top of my hat where they live. Generally in the tropics there are several groups (not sure if orders) of birds that lead very secretive lives.
