Dear Readers, while I was laying on the sofa with my leg suitably elevated I suddenly remembered that I had some bought yet more nature books, and that they were waiting at our local Post Office. So my extremely-helpful husband headed off and returned with this wonderful book about spiders, which has some of the best spider illustrations that I’ve ever seen. The book is full of hard-science and pretty pictures, and what more can you want (other than seeing the Tories booted out which is obviously a personal preference). Anyhow, I found myself intrigued with one species in particular.

Bagheera kiplingi, (male) the more or less vegetarian jumping spider (Photo By Maximilian Paradiz – https://www.flickr.com/photos/maxorz/4360611024/in/photolist-7DkgJG-7CdsDj/, CC BY 2.0, https://commons.wikimedia.org/w/index.php?curid=47104533

This little chap is Bagheera kiplingi, a jumping spider found only in Mexico and Central America. The spider was named originally by entomologist couple George (1845 – 1914) and Elizabeth (1854-1940) Peckham, who specialised in the study of jumping spiders, and who discovered the spider in a trip to Guatemala. They named the species after Bagheera from The Jungle Book, and after Rudyard Kipling, but they didn’t stop there – other spider species were named for Akela the wolf, Naga the snake and Messua, a female character in the book. I’m not quite sure what the link between a tale about Indian wildlife and some spiders on the other side of the world was, but at least it makes the creatures easy to remember.

However, Bagheera kiplingi is unusual in another way – it is the only spider species so far discovered that is pretty much vegetarian. Furthermore, it is reliant not only on a particular group of plants (the Vachellia or thorntrees) but also on just one part of the tree. Some thorn trees produce globules of fat and nectar at the tips of their leaves, which are known as Beltian Bodies. These are produced purely to encourage the ferocious ants that protect the tree to stay put – the ants live in the thorns that the trees produce, feast on the Beltian bodies, and rush out in a frenzy if any passing antelope or monkey tries to eat the leaves.

Ants on the thorn of Vacellia – note the little yellow blob of the Beltian Body  on the leaves to the left (Photo By Ryan Somma – flickr image page, CC BY-SA 2.0, https://commons.wikimedia.org/w/index.php?curid=9031797)

The jumping spider’s diet comprises 60 to 90 percent Beltian Bodies, but grabbing them obviously poses a problem – the ants would clearly kill something as small as a spider very easily. Fortunately, jumping spiders have both excellent eyesight and superb speed and jumping ability, so they can leap onto a leaf and munch a number of planty-nuggets before bouncing away again. They have been observed by scientists as they watch the flow of ants and judge their leap to fit into a gap in the traffic.

Bagheera kiplingi (Female) Photo Wayne Maddison, CC BY 3.0 <https://creativecommons.org/licenses/by/3.0>, via Wikimedia Commons

Not only do the spiders avoid the ants, but they sometimes cheekily supplement their plant-based diet with an ant-larva snatched from the jaws of a worker carrying it to a new location.

Of all the 40,000 species of spider, this is the only one that relies for most of its diet on plants. However, there is so much competition in the rainforest that finding a reliable niche seems to pay off for Bagheera kiplingi. The Beltian Bodies are produced all year round, so there’s no lack of food, and except when feeding the spiders hang out in the drier parts of the plant which aren’t protected by the ants. It all seems like a pretty halcyon existence to me, unless you mistime a jump and get pulled to pieces by angry insects, and presumably the risk pays off. Nature is endlessly surprising and adaptable!

Bagheera kiplingi eating a Beltian Body (Photo from https://spooder.fandom.com/wiki/Bagheera_kiplingi