Good global criteria when identifying unknowns

I’ve been identifying observations stuck at phylum Arthropoda, which is pretty fun. One can often get to a finer ID just by counting legs.

  • 6 legs = hexapoda, and most likely insecta. a lot of beetle and other larvae get identified as myriapods, it’s satisfying to correct those.

  • 8 legs = arachnida, and you can also probably get down to araneae if there’s silk involved

  • many segments and lots of jointed legs usually means myriapoda. 2 pairs of legs per segment = diplopoda, 1 pair of legs per segment = chilopoda EDIT: I forgot about the weird, tiny, shorter ones: symphyla and pauropoda. But those are relatively rare.

  • I don’t have any good tips for crustaceans, but isopods often get identified as another arthropod, so knowing what they look like is helpful.

There are also a lot of egg case observations and gall observations, which I’m not too good at, but I try to annotate those at least.

A few tricky things:

  • pill millipedes and isopods are confusing, so be careful with those.

  • some spiders mimic insects (especially ants) quite well, so make sure those “antennae” are not legs.

  • sometimes arthropods lose legs, which can mess up your count.

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