Some species have chevron-markings on their abdomen. The eyes are small and all about the same size and placed in two horizontal lines. In Clubiona leg 4 is the longest, while with Cheiracanthium it's leg 1. The ground dwelling species of Clubionidae are a group of dark, medium-sized spiders with slender legs. Some species, like Castianeira and Copa, look like ants, while others, like Graptarta, look like wasps.
Sac spiders are free-dwelling, aggressive hunters.
They catch their prey with high speeds and agility by jumping them and grabbing them with their long legs. Clubiona make a funnel of twisted leaves, grass or bark, while Cheiracanthium, which is often found in homes, makes flat sacks in folds of curtains, behind and under furniture and closets. These sacks are disc-shaped, feel papery and have a shiny appearance. The webbing is very strong. The eggsac looks the same but is smaller.