Peptidases were observed in all parasitic species, both at the whole body and pharyngeal level, but the recovery of only metallo-peptidases in Hysterothylacium sp., compared to the observation of several peptidases families in Anisakis spp., may suggest that these proteins could be related to invasive larval behavior, with relevant impact on the pathology in human infections, or to their ability to resist to the host’s body temperature. The gene discussed is LAP3; the disease is infection.