Repeatedly over the course of ant evolution, when called for by particular predatory lifestyles, mouthparts have morphed into a sort of awful bear-trap mechanism. Mandibles are held open with tremendous pent-up energy and slam shut on hapless prey when triggered. This modification is called a trap-jaw, and slightly different versions of it are present in various groups of carnivorous ants.

The single trap-jaw to emerge in the ant subfamily Formicinae (the same group as the carpenter ants) belongs to Myrmoteras, a tropical Asian insect that hunts springtails in the leaf litter. Our lab hosts a few individuals of Myrmoteras iriodum, recently collected from Borneo, and I spent a few hours photographing one last week. You can see the best shots here.

Of all the ants I’ve photographed, Myrmoteras seems the least real. It appears to have sprung to life from the caricatured pages of a comic book.

More Myrmoteras photos here.

David Sloan Wilson on Nowak, Tarnita & Wilson

For those of you following the fireworks over this paper, David Sloan Wilson has a nuanced take on the inclusive fitness debate:

Few people who use inclusive fitness theory are aware of the long list of simplifying assumptions that result in Hamilton’s deceptively simple rule. Nowak et al. are performing a service to the evolutionary community by challenging the assumptions and forcing them to be openly discussed.

The Taxonomy Fail Index

It occurs to me that an objective measure of the amount of Fail in a given misidentification could be useful.

I propose the following:

A = the actual taxon of the pictured organism
B = the taxon as misidentified
T = the number of million years since A and B shared a common ancestor*
H = the number of million years since humans and our closest relatives,
the chimps, shared a common ancestor.

Taxonomy Fail Index (TFI) = T/H

In other words, the Taxonomy Fail Index scales the amount of error in absolute time against the error of misidentifying a human with a chimp.

If I were to run a story about Sarah Palin, but accidentally illustrate it with a photo of a bonobo, that would be a taxonomy fail of magnitude 1.

The classic Taxonomy Fail of possum/cat has a TFI of 24.6.

The yellow jacket/honey bee fail in the last post has a TFI of 25.2, or slightly stupider than mistaking an opossum for a cat.

Snope’s insistence that scale insects are “beetles” (via Bug Girl) is even stupider, TFI = 58. In fact, now that we can quantify the Fail, we see that Snopes fails more than twice as hard as the possum cat.

See? Science can be fun.

* A quick and easy way to get ancestry dates is the timetree of life