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While the thought of a spider often coincides with mental images of a large, geometric, spiral web, many spiders don't use their silk in this way. Some are active hunters, while others build tunnels or burrow retreats. Most of these tunnel-building spiders prefer to sit in their retreat and wait patiently for prey; these spiders are often successful ambush predators.
Trapdoor spiders excavate tunnels -- sometimes quite deep -- and line them with silk to create protected retreats. Many species secure a hinged lid over their underground tunnel to protect themselves from predators. Trapdoor spiders often put trip lines of silk around the entrance of their tunnels and around the perimeter of their hunting territory. When prey triggers the trip lines, these spiders lunge out of their retreats with great speed to capture their unsuspecting prey.
Not all wolf spiders build tunnels, but a few species rely on tunnels to ambush prey instead of actively hunting throughout the night. Like trapdoor spiders, these wolf spiders construct tunnels in which they hide, waiting patiently for prey to walk within striking distance. Wolf spiders have many unusual characteristics and behaviors when compared with other spiders; these hunting spiders lunge on their prey and sometimes roll over onto their backs, clenching their prey in their legs before biting. These nocturnal hunters are often visible while hunting at night; their eyes reflect light much like many mammals.
Funnel weavers are often mistaken for wolf spiders because they share a similar shape and often similar coloring. Many of the funnel weavers commonly encountered in the U.S. are large and various shades of brown with lighter or darker markings. These spiders build large sheet webs that have a distinctive funnel -- or tunnel -- that is open on both ends. Like trapdoor spiders and tunnel-building wolf spiders, funnel weavers sit in their funnels and wait for prey.
Purseweb spiders aren't frequently encountered, except for the sometimes slow-moving males that are wandering in search of a mate. One of the most distinguishing physical characteristics of these spiders is their unusually large chelicerae, or the part of the jaws that the fangs are attached to. These large chelicerae give these spiders a fierce, intimidating appearance. Pursewebs don't necessarily build tunnels, but instead upright, silken tubes with burrows at the end which they rarely leave. They remain hidden in the tubes until prey comes about and then bite through their silken retreat to the prey.
- O. Orkin Insect Zoo: Order: Araneae -- Common Name -- Spiders
- North Carolina Cooperative Extension: Common Spiders in the Landscape
- University of Michigan BioKIDS: Wolf Spiders
- University of Kentucky Entomology: Funnel Weavers & Grass Spiders
- University of Kentucky Entomology: Purseweb Spiders
- University of Michigan Animal Diversity Web: Sphodros Rufipes
- Jupiterimages/Photos.com/Getty Images