hey so anyone with arachnophobia might want to not open that spoiler
Chiwis are terrible spider-like monsters. They're large-sized and have 12 aberration RHD, with good physical stats, okay wisdom, and terrible intelligence/charisma.
Aside from their horrifying appearance, they're pretty standard monsters though. They get some natural attacks with improved grab and constrict, a burrow speed, tremorsense, and a completely arbitrary sonic vulnerability, and that's about it. Not much worth using, especially not at level 12. And that's before getting into the difficulties of using loot, interacting with NPCs, of fighting anything that you can't grab. -0 LA.