Darwin's Bark Spider (Caerostris darwini)
Common name: Darwin's bark spider
Credit: Matjaž Kuntner (Scientific Research Centre of the Slovenian Academy of Sciences and Arts)

Rounding out the top 10 picks is an orb-weaving spider from Madagascar that was named for Charles Darwin – Caerostris darwini. The webs of Darwin's Bark Spider have been found spanning rivers, streams and lakes, and in one instance, a web stretched 82 feet across a Madagascar river with at least 30 insects trapped in it. But length of the web isn't the only distinction of this species. The silk spun by these spiders is more than two times stronger than any other known spider silk and reportedly 10 times stronger than a similarly sized piece of Kevlar.