Darwin's bark spider (scientific name Caerostris darwini) is an orb-weaver spider that produces one of the largest known orb webs, ranging from 900 to 28,000 square centimetres (140 to 4,340 sq in), with anchor lines spanning up to 25 metres (82 ft). The spider was discovered in Madagascar in the Andasibe-Mantadia National Park in 2009. Its silk is the toughest biological material ever studied, over ten times tougher than a similarly-sized piece of Kevlar. The species was named in honour of the naturalist Charles Darwin, with the description being prepared precisely 150 years after the publication of The Origin of Species, on 24 November 2009.