Taxonomy fails irk me. Some might say disproportionately so. They might even have a point. Nevertheless, I think it’s important to at least try to get these sorts of things right, so I was pleased to Alex Wild, over at Myrmecos, taking the time to come up with a formula for figuring out just how wrong a taxonomy fail is. Of course it doesn’t stop people making the mistakes in the first place, but if we have a way of quickly figuring out who’s making the biggest blunders we can, at least, make an attempt to accurately target our … re-education attempts. He calls it the Taxonomy Fail Index, or TFI.

As an experiment, I ran my favourite taxonomy fail through it, and it turns out that calling penguins mammals has a TFI of about 53¹. That makes it about 53 times stupider than calling Sarah Palin a chimp, but still not quite as stupid as insisting that scale insects are beetles.

So there you go.

1. The last common ancestor of mammals and birds was also the last common ancestor of the two great classes of Reptile, the Synapsids and Sauropsids, which diverged some 320 million years ago. Humans and Chimps, by contrast, diverged somewhere between five and seven million years ago. [↩]

I don’t know: no sooner do I start to think I might be doing OK at this taxonomy thing, than someone comes along and knocks me right back down to peg one (to mix my metaphors.)

On Monday, I was able to spot the error in Kevin Z’s WTF without even thinking about it¹ (Echinoderms are not a subset of Insecta; they’re a phylum all their own, and while I can never keep up with whether Insecta is a class or a sub-phylum this week, I do know for sure that it doesn’t contain an entire other phylum. Oh, and it’s not even like Insecta is a subset of Echinodermata; it’s part of Arthropoda)

So there I was, feeling pretty good about myself, when Carl Zimmer comes along and (amidst an entirely fascinating article) hits me with something I never expected: one quarter of all mammal species are accounted for by bats!

That’s staggering. I had no idea they were so successful or so diverse. I’d always thought of them as being slightly odd outliers on the graph of mammal survival strategies; I mean, stretching your arms out hugely and flapping around using sonar to catch insects is just so far from what you expect mammals to do that it didn’t even occur to me that a significant proportion of them might be doing it anyway.

Obviously a quarter of all species is not even remotely the same thing as a quarter of all individuals, but still — how did I not know this? I guess I just haven’t been paying attention.

1. Well, obviously not entirely without thinking about it. [↩]