Early warning system

Blue Mountains Funnel-web spider burrow entrance (Hadronyche versuta) Photo: © R Mascord.

The silk entrance to the burrow of a Sydney Funnel-web Spider has a more or less well-defined funnel-like silk entrance 'vestibule' within which is a collapsed, tunnel-like structure with one or two slit-like openings. The tunnel leads back into a short surface chamber from which the burrow descends. The burrow is often weakly silk-lined and rarely more than 30 cm deep. Typically, silk trip-lines radiate irregularly out from the vestibule margin, extending some 5 to 30 cm across the ground. The spider (hunting mostly at night) sits just inside the entrance with its front legs on the trip-lines. When a beetle, cockroach, or small skink, typical items of funnel web food, walks across the lines, the spider senses the vibrations and races out to grab its meal. The prey is quickly subdued by an injection of venom from the spider's large fangs. Funnel-web spiders may also forage on the surface in the vicinity of the burrow.

If a spider burrow has obvious silk trip-lines around its rim you can be fairly certain that it belongs to a funnel-web spider.