The burrow is the whole strategy. A trapdoor spider excavates a shaft, lines it with silk and closes it with a lid of soil and silk that matches the surrounding ground. Radiating trip lines carry vibration to the spider holding the door shut from below, which opens it, seizes the insect and withdraws in a fraction of a second.
Because a female may never leave, the arrangement supports extraordinary longevity and terrible dispersal. Individuals of the Western Australian species Gaius villosus were followed by the arachnologist Barbara York Main from 1974. The animal numbered 16 was found dead in 2016 at forty-three years old, after a parasitic wasp reached her burrow.
The same immobility explains a conservation problem. Trapdoor spider populations often turn over across a few kilometres, so clearing a single patch of habitat can remove a species that occurs nowhere else.