By Brandon Keim
October 12, 2009 |
Each of the world's 40,000 spider species survives by hunting and killing - except, that is, for Bagheera kiplingi, the world's first vegetarian arachnid.
Found in Central America, the order-defying jumping spider eats nutrient-rich structures called Beltian bodies, which are found on the tips of Acacia trees. Trees produce the bodies to feed ants that defend them, which is a textbook example of what's called co-evolutionary mutalism, and one that B. kiplingi has evolved to exploit.
In a paper published Monday in Current Biology, researchers describe the spider's ant-evading habits and provide a molecular analysis of its body composition, proving that B. kiplingi is indeed what it eats: plants, with a few larval ants on the side. (After all, 400 million years of evolutionary habits die hard.)
A few other spiders have been documented consuming nectar, but only as a snack. No other spider is so predominantly vegetarian. And that's not all: It looks like B. kiplingi males help care for eggs and young - something entirely unprecedented in the spider world.
The researchers are now studying whether there's a link between B. kiplingi's predilection for plants and parental concern. Maybe going veggie softened its heart.
Image: Current Biology