Aphantochilus rogersi (left) with prey

The most astounding arthropod I found in Ecuador last month wasn’t an ant, believe it or not, although it looks just like one from a few feet away.

Aphantochilus is a crab spider slightly over a centimeter long.  The species isn’t exactly uncommon in the Neotropics- in fact, Aphantochilus has appeared previously on Myrmecos. Rather, it is spectacular for its color, size, shape, texture, and movement. Aphantochilus is a convincing stand-in for Cephalotes atratus, the giant turtle ant, and every time I see one lurking about the margins of a turtle ant trail I do a double take and gleefully pass the next half hour watching it work.

Last month’s encounter was the first time I had a camera handy. Thus, some photographs to share with you folks.

A quiet moment

Although it may seem that the spider uses its impressive camouflage to fool its prey, I am not convinced.

The vision of most ants is rather rudimentary, enough that I think it unlikely such remarkable visual mimicry would yield enough of a payoff to be worthwhile. Ants perceive their environment predominately in a chemical medium. Instead, I suspect the spider intends to fool other visual predators- birds, maybe- that would normally pass up acidic chitinous ants but would happily take a spider. For more detailed explorations of the topic, see here and here.

Which is the spider, and which is the ant?

photo details
Canon EF 100mm f/2.8 macro lens & 12mm extension tube on a Canon EOS 7D
ISO 200, f/16, 1/250 sec. Indirect strobe bounced off white paper