A Strange Spider, the Vegetarian Bagheera kiplingi
This is the story of a remarkable spider that feeds almost entirely on plant material. The scientific name of this spider is Bagheera kiplingi, a type of jumping spider (Family Salticidae).
The genus name Bagheera is named after the character Bagheera, the black panther from The Jungle Book by Rudyard Kipling. The species name kiplingi is named after Kipling himself.
It is native to Central America including Costa Rica, Guatemala and Mexico and is only about half a centimeter long.
Males and females of Bagheera kiplingi have different colouration. Males have amber legs, a dark greenish body and a slender reddish abdomen with green lines. Females have amber front legs but their other legs are light yellow and more slender those of the males. The females also have a reddish-brown body and a large light-brown abdomen with dark brown and green markings.
Out of the around 40,000 known spider species on planet earth, Bagheera kiplingi is the only one known to be predominatly vegetarian (some other spiders will supplement their diet with nectar or pollen from flowers, but are mainly carnivorous).
It feeds on the protein and fat-rich beltian bodies on the leaf tips of acacia plants. The beltian bodies are normally there to provide a food source for ants that in turn guard the tree against critters that want to eat it. The ants build nests within the hollow spines of the acacia trees, ready to swarm anything feeding upon it at a moments notice.
The spiders spend most of their time on the tips of old leaves that the ants have already harvested all the beltian bodies from and no longer guard. When the spider decides it wants to feast on some fresh beltian bodies it runs towards the new leaves, dodging and jumping over ants along the way.
The spiders have good vision which they use to determine the best route of approach to the beltain bodies, encountering the smallest number of ants possible along the way.
Once they reach the beltian bodies, they bite one of them off and holding it in their mouth they retreat back to the safety of the old leaf tips. They are then free to feast on their prize without disturbance.
So how on Earth does a spider end up being mostly vegetarian you ask? Well jumping spiders do not build webs and are active hunters of their prey. Beltian bodies have no ability to escape (as part of the immobile leaves) and are on the tips of every new leaf and thus the spider has to expend little energy to collect them. The Acacia also produces new leaves all year round so the beltian bodies are a reliable, consistent source of food.
In nature there is always competition for limited resources, this spider obviously has a niche it can do well in and has no problem competing with the ants.
This spider also has a more sinister side, while about 90% of their diet consists of these Beltian bodies they will also feed on nectar and will sometimes even steal ant larvae carried by passing ants. Occasionally if they're really desperate they'll even canabalise other Bagheera kiplingi.
It also appears that the amount of vegetation in their diets depends on where they live, Mexican Bagheera kiplingi tend to be more herbivorous than Costa Rican Bagheera kiplingi.