Social spiders, who live together in colonies, are rare. Yet scientists have discovered a colony consisting of two different species living together. The spiders are both from the genus Chikunia, making each species as related to one another as wolves are to coyotes, or modern humans are to Homo erectus. Lena Grinsted, a researcher from Denmark, discovered the unusual arrangement when she was performing experiments to see if females would reliably protect the broods of other females.
It soon became clear that there were two species of spiders in the colony she was investigating. The revelation came about following genetic analysis and the discovery of notable differences in the genitals of the species. It’s not clear what advantage the species get from living together, as neither really brings anything different to the party. They don’t hunt together, and can’t interbreed. The only apparent benefit is mutual childcare, as females appear happy to watch the spiderlings of either species.