Burrow security

Five different burrow designs (L to R): Burrow closed by trapdoor;
Open burrow blocked by pebble attached to silk lining;
Hardened abdomen of a Trapdoor Spider blocking the burrow;
Burrow with a side chamber and a second door;
Wishbone burrow with hidden escape tunnel.
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Burrows provide refuge from predators like birds, bandicoots, centipedes and scorpions, as well as buffering climatic extremes for spiders and their young. Some spiders have a trapdoor at the top of their burrow, useful for disguising the burrows presence and ambushing prey. It can also be held shut by the spider or securely silked down when the spider is moulting. Some burrows have extra security within, in the form of additional chambers and doors, escape tunnels and burrow blocking devices like pebbles and loose silk collars. One trapdoor spider (Idiosoma nigrum) even uses its thick, hard abdomen as a plug against burrow invaders.

The entrance to a Wolf Spider's burrow.
Now you see it...