A perpetually happy Venezuelan Leptogenys
We don’t really know why some species of Leptogenys hunting ants sport a permanent grin. The oddly ecstatic mandible shape might, however, have something to do with handling the broadly curved exoskeleton of their preferred prey: isopods (the sow bugs and pill bugs).
Flickr user “venwu225” recently uploaded a fantastic series of the related species L. falcigera in action. Some of the shots show how the mandibles allow the ant to grip the isopod both above and below its wide skirt of armor. Cool stuff.
photo details: Canon MP-E 65mm 1-5x macro lens on a Canon 20D
ISO 100, f/13, 1/250 sec, flash diffused through tracing paper