Imagine, for a moment, the horror if we humans were stalked by a common predator that hid itself in the open by looking...just like us. A humanoid patrolling the streets like a bloodthirsty mannequin, picking off pedestrians that venture too close. Fortunately for us, this sobering thought is only a grim fantasy.
Australian weaver ants, however, routinely face just such a nightmare predator. Several species, in fact. Weaver ants (Oecophylla smaragdina) contend with a number of ant-like spiders that look similar enough to their favored food to avoid detection by the ant guards. They lurk around the ants' trails, pretending to be ants and grabbing a meal when the opportunity arises.
During my recent travels in tropical Australia I spent a morning observing an ant-mimic crab spider Amyciaea albomaculata. The following photo essay shows the spider at work.
See also Aphantochilus rogeri, a New World crab spider that attacks turtle ants: