I am always amazed at the answers in , especially for insects and plants. It seems like a grainy photo, a vague description, and very broad geographical location (often just a continent) is all that it takes to pinpoint a species. Yet there are millions of species! That seems remarkably efficient from an information theory standpoint to me.

Before asking online I always try to identify my critter myself first, and I never have much luck.

  • Searching by traits ("large green head with black oval eyes and slender body") turns up too much irrelevant information
  • Binary tree style identification flowcharts seem hard to find, and having used those to identify microorganisms I get the impression that they tend to be very imprecise
  • Phone apps and similar software seems absolutely useless 99% of the time

But somehow the answerers are able to identify species so easily and so accurately. How do you do it? What's your secret? Do you just have encyclopedic knowledge of all the common species out there? Are there just lots of clade nerds lurking this site, who each know everything about one cluster of species, and it's just that whatever the species there happens to be someone on this site who knows it? Or is there some kind of system for IDing even species you haven't heard of before?

  • 1
    $\begingroup$ What helps a lot is a precise information about the location. And then patience and Google image search. And sometimes you actually know the plant/animal. So, no magic involved :-) $\endgroup$
    – Chris Mod
    Commented Mar 14, 2017 at 7:36
  • $\begingroup$ IDing things you already know is neat because you can provide a lot of pertinent info about it to easily educate others. However (for me at least) answering questions in which I have absolutely no idea what I'm looking at are often times more fun! :). In that case, a lot of Google image searching happens. I still always make sure I'm finding a reputable site to back up anything I find via google. In those cases, the more info the better - so I agree with @Chris that location is often key $\endgroup$ Commented Mar 14, 2017 at 16:13
  • $\begingroup$ @theforestecologist Yes, this is the fun for this questions. Finding something completely unknown, kind of a scavenger hunt :-) $\endgroup$
    – Chris Mod
    Commented Mar 14, 2017 at 16:20
  • $\begingroup$ @Chris, right! I think of it as a puzzle. I've been doing species IDs for years for friends/family/coworkers -- this site just gave me more puzzles to do!! :). $\endgroup$ Commented Mar 14, 2017 at 16:22
  • $\begingroup$ I definitely have a good understanding of most major phyla and often can ID something to a specific order/family, so I can usually look at something and instantly narrow my options. Also, I've been IDing for a while, so I often have an idea about what I'm looking at. When I don't, after narrowing taxonomically, it's all about searching using relevant key words and being able to recognize seemingly related species that come up. Recognizing that search picture species are related just on appearance is key to allow me to follow those "rabbit holes" to gain more info and inch my way to an answer $\endgroup$ Commented Mar 14, 2017 at 16:37
  • $\begingroup$ Answered a few species-identification questions, the idea was to search and search...until I got the right species or sometimes just the genus. The process is very engaging. $\endgroup$
    – Tyto alba
    Commented Mar 16, 2017 at 13:41

1 Answer 1


Some thoughts....
In general, having good overall knowledge of groups (orders/families etc) and their characteristics can quickly narrow down the answer set, which makes searching for traits more efficient and practical. Therefore, having a good overall background in e.g. entomology (or botany etc...) can allow you to relatively quickly arrive at the correct order, family genera etc more easily. Without more knowledge, dichotomous identification keys are often relatively useless, since they are often useful only in specific regions, or can only determine individuals to e.g. the level of order.

However, we definitely also get overconfident answers, where the answerer underestimates the difficulty of getting correct ids to the species level only from one or two pictures (I may also be guilty of this). There are often sets of species that require deep knowledge and day to day familiarity with the species (i.e. looking at them regularly) to id them correctly. Also, the information you find on the internet is scattered (at best). Just because the overall appearance fits with one particular species present on the internet (with a couple of pictures, some basic info etc) doesn't exclude that there might be several other extremely similar species, only known to specialists on that particular taxon. Even so, providing a suggested ID isn't a problem, as long as it is done in a humble way, acknowledging that there might be species unknown to you and clearly stating your level of expertise. In that way, the OP can interpret the reliability of the answer in a better way.

So to your bullet points:

  • Yes, but together with e.g. Megachilidae found in Germany you might have more luck.

  • I agree, in the sense that they are either only useful for very broad classifications (e.g. orders), or very narrowly (Longhorn beetles in Scandinavia). Also, most really good determination keys (of the latter kind) are found in specialist books that are not found openly on the internet.

  • There exist some good ones, but, again, they are usually only useful on specific regions or countries. I haven't used that many species-ID apps though.

  • 2
    $\begingroup$ Information not found on the internet? Well I never! $\endgroup$
    – Superbest
    Commented Mar 14, 2017 at 14:44
  • $\begingroup$ @Superbest I know. It's hard to fathom. $\endgroup$ Commented Mar 14, 2017 at 15:21
  • $\begingroup$ Right, so even though dichotomous keys would be super helpful at times, in most cases either 1. the species in question is from a specific place requiring a specific key to that place (which most users will not have and which are typically not online) and 2. most keys require inspection of minute details to differentiate species (e.g., jaw structure or gonads of insects and magnified seed or leaf detail in plants) which would require up-close inspection of the OP's specimen -- again usually not possible. $\endgroup$ Commented Mar 14, 2017 at 16:20

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