Click to enlarge. Credit: AMNH

A field of spigots is seen in this electron microscope close-up (a) of the Thaida peculiaris spider's silk-spinning organ, or cribellum. The spigots, seen even closer in an image of the Filistata insidiatrix spider (b), extrude liquid silk through openings at the bulbous end. The pressure of the extrusion and manipulation of the silk by the spider's legs transforms liquid silk into a flexible thread. Spider hairs, or setae, on the abdomen (c) can contain sensory neurons and irritating chemicals for attacking enemies. The scales (d), made of chitin, are responsible for the brilliant colour and iridescence of some spiders.

These are four of more than 32,000 images from the Phylogeny of Spiders project, part of the international, US-funded Tree of Life initiative to create an evolutionary map of all plants and animals using genomic and physical data.