All spiders, with one known exception, are carnivores. That exception is Bagheera kiplingi, a jumping spider whose relatives seem quite normal, but which has taken up a mostly vegetarian lifestyle. It does this by eating the nutrient-rich Beltian bodies on acacia trees that are tended by ants. If you Google “Bagheera kiplingi”, you’ll find references to studies by Christopher Meehan and colleagues.
The last time I saw the species live was in 1983, and following its fame I wanted to see it again. When Heather spotted a bullhorn acacia as we were driving near San Mateo, Jalisco, we decided to stop the car for a moment. Without even opening the window, I saw a Bagheera kiplingi crawling on the plant. Woohoo! Here are a male and female that we found. The female has normal jaws that hang down from the face, but the male has jaws (chelicerae) that stick forward, instead of down.
As thrilling as it was to find Bagheera kiplingi, there was a cost, as Heather recounts in her blog post about Gasteroposting.