 In poecilostomatoids the mouth is represented by a transverse slit, partially covered by the overhanging labrum which resembles an upper lip.Although there is variability in the form of the mandible among poecilostomatoids, it can be generalized as being falcate (sickle-shaped).The antennules are frequently reduced in size and the antennae modified to terminate in small hooks or claws that are used in attachment to host organisms.