There Is A Spider That Is Almost Completely Vegetarian

“Because some [animals] have no compassion, feeling, or reason, are we to possess no compassion, feeling, or reason?” —George Nicholson, Remarks on defenses of flesh-eating

In A Nutshell

We think of spiders as viciously predatory, injecting venom into their prey and sucking out the liquefied innards. However, there is one species of jumping spider, called the Bagheera kiplingi, that subsists almost entirely on nutrient-rich leaf tips. Scientists are somewhat baffled as to how this spider developed a vegetarian diet or even how it manages to digest plant matter in the first place.

[Note that the above is actually a photo of a different species of jumping spider, due to the rarity of pictures of Bagheera kiplingi.]

The Whole Bushel

Even those who did not overtly suffer from arachnophobia are often unnerved by the presence of spiders. It is thought that this is an evolutionary trait, a “healthy fear.” While the majority of spiders are capable of giving us little more than a painful bite, the most dangerous species can be lethal, and are best avoided entirely. We view spiders as wicked, cold-blooded predators possessed with a depth of cunning. There is one species of spider, however, that isn’t bloodthirsty at all.

The Bagheera kiplingi, found in Mexico and Central America, is unique among the 40,000 or so other known species of spider in that it subsists almost entirely on a herbivorous diet. The name comes from Bagheera, the black panther in Rudyard Kipling’s The Jungle Book collections. It is a bit of a misnomer, as this spider isn’t much of a hunter at all.

Article Continued Below

They are arboreal, typically living in Mimosaceae flowering trees. Their main food source is a nub at the end of the tree’s leaves called a Beltian body. This structure is rich in fat, protein, and sugar and is used to fulfill a symbiotic relationship with ants. The ants eat the Beltian bodies and in turn keep away more destructive creatures. To share a food supply with the aggressive ants, the spiders are very quick and dexterous, dodging in to grab some food and then scuttling away at velocity. While the Bagheera kiplingi tends to carefully avoid these ants, it isn’t entirely herbivorous; it will occasionally munch on ant larvae and cannibalize other spiders during the dry season, when their regular food supplies are short.

Although they have been known for over 100 years, the rainbow-colored, jumping B. kiplingi is still something of a mystery to scientists. They aren’t quite sure how the spider digests its food or how they evolved toward their peculiar diet in the first place. It has been speculated that the intense competition for resources slowly drove previous carnivorous spiders to take up alternate food supplies.

Show Me The Proof

Featured image photo credit: Opoterser
BBC News: ‘Veggie’ spider shuns meat diet (with video)
Not Exactly Rocket Science: Bagheera kiplingi—the mostly vegetarian spider

Looking for our newsletter? Subscribe here!