Sackspinnen

Sackspinnen, commonly known as sac spiders, refer to several genera of hunting spiders that do not rely on conventional webs to capture prey. They typically hunt by active foraging and use silk to create retreats or sacs for protection, often in crevices, leaf litter, bark, or inside human dwellings.

Taxonomy: Sac spiders have historically been placed in the family Clubionidae, but modern classifications have moved core genera, especially Cheiracanthium, into families such as Cheiracanthiidae or Eutichuridae depending on the taxonomic system. The common name Sac spiders describes several related genera rather than a single, narrowly defined group.

Appearance: They are usually pale yellow, tan, or greenish, with a slender body and relatively long legs. Size ranges from about 5 to 15 millimeters in body length, depending on species. Some species show darker markings on the abdomen or carapace.

Distribution and habitat: They are cosmopolitan, found worldwide in a variety of habitats including forests, grasslands, gardens, and human dwellings. They often prefer warm microhabitats and are more active at night.

Behavior and ecology: Sac spiders are active hunters, relying on venom to subdue prey rather than web traps. Silk is used for retreats, egg sacs, and for securing prey after capture. Females often guard egg sacs and may carry them before dispersal.

Humans and medical relevance: Bites from sac spiders are occasionally reported and can be painful; severe reactions are rare. The exact medical significance varies by species, with some European species such as Cheiracanthium punctorium historically associated with notable bites, though evidence of widespread necrotic lesions is limited and medical attention is advised for suspicious bites.