Borrowing from similar creatures...
Web (Ex): A crystal spider can throw a web eight times per day. This is similar to an attack with a net but has a maximum range of 50 feet, with a range increment of 10 feet, and is effective against targets of up to Medium size. The web anchors the target in place, allowing no movement.
An entangled creature can escape with a DC X Escape Artist check or burst the web with a DC X Strength check. The check DCs are Constitution-based, and the Strength check DC includes a +4 racial bonus. The web has 6 hit points, hardness 0, and takes double damage from fire.
Crystal spiders can create sheets of sticky webbing from 5 to 60 feet square. They usually position these to snare flying creatures but can also try to trap prey on the ground. Approaching creatures must succeed on a DC 20 Spot check to notice a web, or they stumble into it and become trapped as though by a successful web attack. Attempts to escape or burst the webbing receive a +5 bonus if the trapped creature has something to walk on or grab while pulling free. Each 5-foot-square section has 6 hit points, hardness 0, and takes double damage from fire.
A crystal spider can move across its own sheet web at its climb speed and can determine the exact location of any creature touching the web.