Come into my parlour

SPIDERS are known for many things. Sociability is not one of them. Most spiders are more likely to try to eat their neighbours than befriend them. Given that there are at least 43,678 species of the critters, though, it is not too surprising that a few have overcome their natural grumpiness and teamed up to form societies. So far, about two dozen such social spiders have been identified. And among them, something really strange has just been found. For one type of spider society turns out to involve two different but closely related species. It is as though anthropologists had discovered villages populated both by human beings and chimpanzees.

This was discovered by a team led by Lena Grinsted of Aarhus University in Denmark. They were studying a social species of spider called Chikunia nigra, living near Beratan Lake in Bali. Later, as they looked in more detail at their specimens, they realised its genes and genitalia revealed that it was actually two species, according to their findings just published in Naturwissenschaften.