How to Support iNatters in Creating ID Resources & Guides? Case study: How to Identify Speckled Swimming Crabs (Arenaeus)

One of the top 20 most observed crabs on the iNaturalist is the Speckled Swimming Crabs (Arenaeus cribrarius).

Swimming crabs (Family Portunidae), have paddles on the tips of their back legs and many of the larger species are often eaten, such as the familiar Atlantic Blue Crab (Callinectes sapidus)

But the genus Arenaeus has two species in it. Speckled Swimming Crabs on the Atlantic coast of the Americas and the lesser known but very similar Pacific Speckled Crab (Arenaeus mexicanus) on the Pacific side.

When I looked yesterday there were only 13 observations of Pacifici Speckled Crab. I wanted to see if I could find some more among the other swimming crab observations but I’m still not super well versed in the swimming crabs.

In my experience, once you’re familiar with identifying a group of organisms, you go by gestalt. By that I mean what goes on in your brain as an identifier is more like recognizing people you know. When we look at a picture of a friend, we just say “thats Jack” we don’t count the number of freckles. The same goes with species. I’m pretty familiar with lots of crabs and its much easier for me to just say what crab it is than to pick out individual characters and explain why I think that (e.g. “uh, its shell is bumpier and the way the spines are is different”). Getting a feel for gestalt just comes from experience and is hard to explain or teach.

In contrast learning how to identify a species and explaining how to identify a species is often much easier to do when there’s a specific character to get a handle on. I had trouble wading into the genus Arenaeus because there are a lot of other swimming crabs and I didn’t have a good feel for the gestalt of the group. I usually turn to the museum literature for characters but this can be extremely frustrating because often the literature focuses on characters that might be good for a preserved specimen but rarely show up in photos (e.g. hence so much focus on things like the shape of sexual organs). Also the jargon and unfamiliar anatomical terms in the museum literature can be really hard to translate.

Thats why I was so excited to find this great character for identifying Arenaeus. Its described in the literature as “Superior fissures of orbit open , V-shaped” but it wasn’t until I found this great FAO guide in Spanish for identifying Pacific fisheries species that I understood what that means. The character shows up amazingly well iNat photos as shown below:

The most similar crabs to Arenaeus in the range are swimming crabs in the genera Callinectes and Portunus. In these species the notch is closed and much less well marked as shown below:

Once I had this character to hook on to, after flipping through some North American Swimming Crab observations in the identify tool I was quickly able to develop a sense of gestalt for the players in this group beyond this one character. I was able to more than double the number of observations of Pacific Speckled Crab pretty quickly.

I wish we could figure out a way to encourage the sharing of this type of information more on iNaturalist. My sense is its so much easier for identifiers to just identify other people’s observations than it is to put things in terms like this that help people learn how to identify a species and develop a sense of gestalt and build bridges with the often inaccessible information in the museum literature. Its kind of like the whole “give a man fish vs give a man a fishing pole” and I think teaching one another how to identify is going to be critical if we’re going to continue to scale the number of identifier on iNaturalist alongside the rapidly growing number of observers.

I think the reality is authoring this kind of content takes a lot of work. But there must be something we could do to make it more painless. What would that be? And what kind of format/distribution is best for creating and sharing kind of content and what kind of technology tools could accelerate it? Looking forward to hearing ideas from others. And if possible, I’d love to see other attempts at explaining how to ID a species even if its just focused on a single obscure genus with two species as in this case here…


@nathantaylor may have something to say on the topic. He’s provided comprehensive resources and guidance on his areas of expertise – enough that when he need(ed) to take a break from IDs there were enough identifiers to pick up the slack. A number of whom learned from him and/or use the resources he’s created.
At this point despite the scaling issue, American Euphorbia and especially subg. Chamaesyce still have a fast review rate from days to weeks in many cases.


This is certainly a topic I am interested in and can sympathize with. I feel like the foundation of sharing identification information is creating identification guides to link to (like the collection here or here). Otherwise, it’s simply infeasible to keep up with identifications and explain the details. I also like doing a taxon group by taxon group approach in line with the resource written so that I can keep the same link copied to the clipboard and distribute it to as many observers as possible at the time of writing.

To me, it seems like identifications to engage with observers generally fall into three categories: 1. Post a link to identification, very short explanation. 2. More involved post; actively trying to engage the observer with the information. 3. Following up with the observer to actively recruit for more observations/identifications. Depending on the user, this can translate into actually mentoring and training of new identifiers.

In my opinion, a good mix of guide creation, speed identification with or without links to guides, and training new people who can help to fill your shoes when needed to really excel in spreading the identification information is probably best. And yes, it is a lot, especially for a group like Euphorbia that has 185 species and about 65,000 currently documented for the US, but it can be extremely satisfying.

The main problem I always run into these days are time constraints/differences in where I’m interested in devoting my time. The amount of engagement you get is proportional to how much time your willing to invest. I suspect that the time needed to provide good engagement scales exponentially with increased observations making things more challenging. Training too many complete newbies can be draining, especially if the only species in their area are common. I’ve always wanted to try to recruit more folks from areas with a lot of the common species specifically to help curate, but even finding those individuals can be challenging with the large numbers of observations and observers.

Another problem is actually managing to communicate with all of them once you find them. I usually get ID requests daily from around the world and usually end up with about 3-5 each week that require a well thought out reply. Other things that sometimes complicates this for me is that I have a lot of undescribed variation (whether it be new species or populational variation) to deal with in some areas, so I can’t even really point to an article or a journal post I’ve made to resolve the situation. This is particularly true in Mexico, where I probably get half of my ID requests from. I sometimes wonder if it might save time to finish up describing and publishing the variation, but given my procrastination, it probably hasn’t gotten that bad yet. :-)


To follow up on the mentoring/training side of things, I actually have created some custom identify links for a couple of the other power identifiers that I’ve helped train to check their work and make suggestions as needed. I’ve included species their unsure about or want some additional input on. It seems to work pretty well. Not only do I get to double-check their work on less familiar species, but I also get to see their improvement which is extremely motivating. @trh_blue and @janeyair are more than welcome to comment on whether this has worked or not for them if they want (and feel free not to hold back on any criticisms too :-) ).

I have some other ideas of expanding the effort in Euphorbia, but haven’t really been able to get them up and running yet. For instance, I actually have a tutorial that is nearly done, but I had to stop working on it a while back to focus on grad school.


It’s so good that it was/is one of our recommended practices for our team of mentors over at the ID-athon May 2021! (and Mentorship Program), and almost all of them will be using it to help their students.

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I wonder if changing the Topic Title might get more people contributing to this important topic? It seems to me that you are seeking feedback and input on getting folks to share this kind of ID resources/guides on iNat and Speckled Swimming Crab is just a great example (not the focus of the topic) of why this type of content is valuable to iNat. I almost didn’t read the topic because of the title (I like Crabs but I am more interested in other organisms) but I am glad I did read it once I got to the questions you ask about how to encourage folks to create ID resources/guides and the responses you are receiving. Maybe a title as simple as How to Support iNatters in Creating ID Resources & Guides


(naturebugs I changed the title)

nathantaylor thanks for sharing your experiences. The “identification guides” you refer to are mostly personal journal posts right? ie just unstructured text? Does this formal work pretty well for conveying the information you want to share? Or are there certain things (e.g. allowing photo upload) that would make it a lot easier?

Yep, journal posts usually with photos embedded and they usually work pretty well if a bit time-consuming. Allowing photo uploads would definitely help, but I really like linking the photos to observations when possible so that viewers can actually go to the example provided and compare to other observations. The thing that takes the most time is trying to scale the photos correctly so that they can be viewed next to one another without one being larger than the other.

I take a lot of different approaches depending on the species group I’m working with, but I like to incorporate photos where possible. I’ve included a few examples below that I think are pretty representative of what I usually post (a full list of my Euphorbia of the US resources can be found here. I’ve also added a few examples at the bottom not in Euphorbia that I wrote as part of my ongoing effort to put together a flora of the High Plains of Texas.
More recent example with little text:
More lengthy explanation:
Explanation of subgroup:
Explanation of morphological characteristics:
Oenothera draft species treatment:
Astragalus draft key:
Discussion on the taxonomy of Malvella:


This is a great topic, and one that should be discussed and addressed further.
I have tried to gather and organize some ID tips and guides, mostly for portuguese/iberian fauna. They’re presented on my iNat profile.

I’ve also made a collection of useful Facebook Identification Groups .


I wonder if providing some templates may make it easier to support ID resource developers?

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The two big blockers, in my mind, are:

  • Where do I put information I want to share?
  • Where do I look to find information others have shared?

The natural answer to the first question is to put it where others will look for it and notice it, so essentially the two questions have the same answer. After that, it all comes down to hassles and obstacles which have to be overcome by content authors and editors to get anything visible done at all.

I think the most obvious place to look for information about (identifying) a taxon, on iNaturalist, is the taxon page. BugGuide does something like this, where there are tips for distinguishing species within a genus on genus pages, tips for distinguishing genera within a family on family pages, and so on, and detailed descriptions on species pages. When there are guides which cut across taxa, they’re linked to from all the relevant taxon pages.

Finding identification tips by visiting taxon pages on BugGuide is a lot easier than searching observations for rare identifier comments (something BugGuide and iNaturalist have in common). Having an obvious place to look shouldn’t be underestimated.

As for creating and hosting content, I’m probably more comfortable with the process than 90% of identifiers out there (I know how to edit photos, I have a degree in Computer Science, and I work with web servers as part of my day job), so I may have a warped perspective on what the common obstacles are, but I’ll try. I think normal people overwhelmingly prefer “What You See Is What You Get”-style editors vs directly writing HTML or Markdown or any other code-like things, no matter how simplified. This can be mitigated somewhat by having side-by-side code editing and result windows. WYSIWYG editors are also preferred over “Wizard”-style setup dialogs with multiple steps. People like to get immediate feedback from every change they make so they can experiment, rather than getting railroaded through a whole series of forms where it isn’t entirely clear what the consequences of each action will be. A lot of people will give up halfway through a Wizard.

It’s rare that a single person is able to create a fully detailed guide by themselves. I therefore think it’s critical that many users be able to edit and contribute to the same same content pages. Vandalism might become a problem, but it’s a much easier problem to manage than having zero content or masses of low-quality duplicate content which can’t be merged or improved. The Wiki model, content editable by (almost) everyone, seems to be better than all the other alternatives in the long run.

Maybe you can see where I’m going with this. I’ve said it before (and elaborated). I don’t think I’ve emphasized, before now, how much the lack of bare-bones, free-form tools prevents things from getting started. Every thing a new person has to learn is an obstacle to them ever getting anything done.

I also haven’t emphasized how important it is for there to be an obvious place to start looking for information. Even a search box can be an obstacle if you don’t know what to search for. The flip side of this is that it provides an obvious place where working on content will have a big effect. Nothing’s more demoralizing than putting a ton of effort into something that you then realize almost no-one will ever see. Nothing’s more motivating than knowing that lots of people will see your work (or knowing that lots of people are looking at something incomplete).

So: set up a wiki. Put it somewhere obvious, like or Import the content from taxon articles into the taxon pages, like you already do for Wikipedia articles.


I think this issue is definitely the next frontier for improving participation in iNaturalist at the observer and identifier level. I’m hoping some general frameworks for building photography based identification guides could be built so that people could build there own easily for a new group.

@Megachile and @jeffdc are working on a cool project for galls.


I personally don’t like the idea of wikis for identification guides as much (though I do support this for introductory info) and I might not end up using them except as a place to copy and paste to from my own guides. Part of the satisfaction of putting together a guide is that you learn all that is known about a group for an area, add the information and know that you’re responsible for the information that goes out. Also, identification guides are almost always location specific. This doesn’t lend itself well to a centralized wiki in my opinion.

With a wiki, I’d also imagine that it would be susceptible to differences in taxon concept. That could get really messy. For instance, say I post information on Euphorbia grantii (the currently accepted concept) and someone else is using the name to apply to the commonly cultivated Euphorbia grantii based on Synadenium grantii, this necessitates ongoing vigilance to correct taxonomic concept. There are much more difficult examples than this one. What I think would be better is a more obvious location on the taxon page to display links to helpful resources separated by user generated resources and external resources.

Perhaps this could be accompanied by a simpler version of “Guides”. The old guides are nice, but overly complicated. A newer version of guides really wouldn’t have to differ much from journal posts in style as not much more is needed than the ability to list taxa, embed and upload photos, add text, and add hyperlinks to create a good guide. I like the freer style of the journal posts even if it does require knowing two html commands.

If these two were put together (guides where you could add taxa and taxon pages that pick up on these taxon names), relevant guides could be automatically linked to the taxon page. Perhaps you could even restrict this based on location if you put in the option of a location parameter on the guide.


Focusing on the technology to facilitate guide creation, I don’t know if providing the technological tools as a component of iNaturalist would encourage more guide creation…I just honestly don’t have a way to judge that. For me, Google Slides has checked all the boxes. It’s super easy to paste images, annotate the images, and even create clickable “keys” of sorts. Mistakes can be fixed without having to recreate annotated images from the original file–which I’m loath to do because of the extra time and file organization that requires. With Google Slides, each component can be edited, adjusted, and improved right there in the one document and from any computer with an internet connection. IF a custom iNat tool was created, I think it would need those features.

A couple of examples:

Personally, I created guides because I wasn’t able to remember the identifying features after I discovered them. I kept having to look them up time and again. So I decided to put together an illustrated guide for myself. Then figured everyone else would benefit from it also.


Our site (, which we’ll be announcing on here soon) began from my wish to add features to the iNat guide tool. To achieve that, we’ve had to replicate it from the ground up (without the support of iNat’s existing taxonomic and mapping infrastructure), and the result is something we’re really proud of but which of course is entirely dedicated to one kind of phenomenon and not easily ported to other taxa. Now that we have it, I’m more convinced than ever that iNat should just build a more robust version of the guide tool, which retains the custom filter/tag system but with better support for images and especially managing quotes from primary sources (these are invaluable for us and I imagine they would be for other taxa as well). The fact that ppl continue using the Guide tool as-is even in its limited state and without ongoing support seems to suggest that it’s something people would use even more if it were replaced/expanded.

One other tool we’re considering adding is something similar to @cazort’s comparison tool, which presents illustrated side-by-side tables showing diagnostic differences between a pair of species. A tool like this built into iNat could automatically link from each taxon page included in a comparison.

Another thought is that, given all of the existing resources people have been mentioning here, iNat could simply find a way to make links to such external pages more convenient to create and more salient to users. At the moment, the “more info” tab is full of automatically generated links to sites that generally contain no information, and they require a click through to the About tab to even see. Not sure the best way to do that though.


Sounds exciting. I know you’ve put a ton of work into it.

I’m wondering if another advantage of having iNat build and maintain the guides framework is that it would make it easier legally speaking to share observation photos directly from iNat on the guides. My understanding is that licensing issues (cc-by-nc) actually limited the photos you could pull in on your website. That’s another consideration for building a guide that can be responsive to knew information and get the most of interacting with iNat.

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My understanding is that we can use any CC images by default and can get permission to use all rights reserved images.


Yes @nathantaylor your system has worked well. It is seamless and I wouldn’t know anything was happening with custom links if you hadn’t informed me and @trh_blue beforehand asking for our input.
How did I end up helping with IDs? Nathan’s willingness to engage with me on Euphorbia sect. Anisophyllum had peaked my curiosity about these fascinating plants (I do love weeds). His guides were extremely helpful as well. It has been a rewarding and stress-free ;) experience


My two cents, the single best thing that I think people could do to facilitate my creation of ID resources and guides like the ones I’ve been doing, would be to address my concerns about image licensing that I’ve raised in other threads, most notably this one (which is now closed).

The limiting factor in my ability to make these guides is often my ability to quickly find photos for them. The dominance of licenses with the NC clause in iNat’s pool of photos (which I’m skiddish to use for reasons I explain in that linked thread) is a major limiting factor. And I do believe that those NC licenses are so dominant mainly because they’re the default and the language iNaturalist presents on signup strongly recommends them, as the “the best license for sharing with researchers.” something I dispute vigorously.

I was frustrated that that thread was closed, and it’s been around six months since I brought the issue up, but the issue was not resolved, and in fact, nothing whatsoever has changed. iNat still defaults to a NC license, still does not allow the selection of any non-NC CC license on signup, and still misrepresents the implications of that license on signup with that misleading text. And there has been no prompt to encourage users to revisit their license, which was another potential solution that was discussed.

I would ideally like iNaturalist to be more dynamic and responsive at addressing and resolving concerns brought up by users in a timely manner, especially active ones who are putting a lot of energy into the site.

Permission is tricky. I want my resources to remain freely and openly available to all, and as such, I may want to release them under CC licensing. In some circumstances, depending on the nature or structure of what I’m creating, I might be legally required to release them (such as if making a photo collage which contains an image with a CC-BY-SA license.) The same is generally required if you are to add the material to Wikipedia or some other resource published under a copyleft license, such as a copyleft textbook or course materials.

When I ask for permission I usually ask if someone is willing to release their images under a license like CC-BY-SA or CC-BY, so that I can include them in material released under such a license.

If you are just looking to publish a single guide that cannot be built off of or reshared other than by citing or linking to it, then simply asking is sufficient. But I think that, for the long-term life of the material and greatest reach, open licensing is better. Organizations and people reach their end-of-life and if it isn’t open-licensed and arrangements aren’t made, the material may be lost forever. On the other hand, good open-licensed material typically gets shared far and wide and will never be lost.