Small jumping species steals lunch from ants.
A little eight-legged pickpocket that darts around acacia trees could be the first known vegetarian spider.
Bagheera kiplingi belongs among the big-eyed, athletic
predators in the family of
jumping spiders and gets its name from a panther in a Rudyard Kipling story. Yet
a population of these spiders in
A few other spider species do taste vegetable matter now and
then, says Yael Lubin of
These arachnid herbivores are no wimps. “The tree is full of
biting, vicious ant guards,” Meehan said during the 12th International
Behavioral Ecology Congress meeting August 9 through 15 at
Acacia trees and their resident ants have become a textbook example of a mutually beneficial partnership. Tree thorns grow swollen bases the right size to shelter ants. Glands at the base of the leaves ooze nectar, far from flowers but just at the spot to offer refreshment for ants. Acacia leaflet tips sprout nubbins of protein and fat suitable for ant snacks.
Certain ant species take full advantage of these comforts and defend their home trees against all comers. In the course of their vigilance, the ants get rid of caterpillars and other invaders that might chew on the tree.
Meehan says the spiders manage to dodge the ants, perching on leaf tips and nesting in mature leaves, which aren’t as heavily patrolled as other tree parts.
Ecologists have studied the partnership for years, but “people who look at ant acacias — they look at the ants,” Lubin says. “It took the eyes of a student naturalist to see this.”
That fresh observer was Meehan, who, along with his Villanova
colleague Robert Curry, noticed the spiders dining on the leafy snacks of
Those meat moments don’t happen often, according to studies
done in collaboration with Matt Reudink of Queen’s University in
That carnivore signal does not show up in the acacia-tree spiders, which carry a relatively light concentration of N15, one that is typical of plant-eaters, according to the team’s data. The researchers also found that the concentration of the heavier form of carbon, C13, also looks typical for a vegetarian.
Meehan, C., and R.L. Curry. 2008. Exploitation by a predominantly vegetarian jumping spider (Bagheera kiplingi) of Acacia mutualism through ‘clever’ avoidance of ant-guards. 12th International Behavioral Ecology Congress. August 9–15. Ithaca, NY.
For pictures of ant-plant partnerships (pictures open in separate windows):
Milius, S. 2005. Proxy Vampire: Spider eats blood by catching mosquitoes. Science News 168(Oct. 15):246. Available at [Go to].