Once scouts reach that decision, their behavior changes. Each scout dashes back to the nest, but instead of coaxing a nest mate for a tour, she just grabs somebody. She uses a mouthpart hook, an over-the-shoulder throw, and off she goes with the passive nest mate curled on her back in an ant version of the fetal position. Carrying takes about a third as long as leading would, and scouts can haul the rest of the colony to a new home within hours. The ants shift from the independent info gathering of scouts to group implementation of the quorum's decision.
I do not understand the usage of in the bold sentence. It throws me off when only "off" stands there. On top of that, though it is logic to look "an over-the-shoulder throw” as an appositive of "mouthpart hook," but I just do not think these two are connected.