The dagger spider was a Rahi insect of Voya Nui which attacked its victims by stabbing them with their front legs, injecting them with a paralyzing venom.
These spiders were often seen on Voya Nui swarming out of cracks in the earth, particularly in the forested "green belt" around the edge of Voya Nui. Unlike most Rahi spiders, these creatures did not bite their enemies. Rather, they made a move as if they were going to bite, then stabbed with their front legs to inject a paralyzing venom. The sharpness of these legs gave them their name.