When the twilight gill arrived in the Vailnoff ocean, it encountered a bizarre, slug-like organism. While the creature seemed benign at first, some would ultimately become a major nuisance. Without access to much iron, the partially lithotrophic winged litusfoi saw the twilight gill’s exposed gill filaments as nothing short of a smorgasbord of iron. Some winged litusfoi would latch onto the gills and digest their epidermis, causing the twilight gill’s blood to rush into the winged litusfoi’s digestive surface. These winged litusfoi would ultimately become the vampire litusfoi.
The vampire litusfoi has changed little from its ancestor and uses much of its underived anatomy to aid in feeding. It will first drift lethargically through the water column, waiting for a twilight or midnight gill to arrive. It will only move if disturbed by a predator or if it comes across a host. When a host runs into the vampire litusfoi, the vampire litusfoi will latch onto its host and crawl towards the gills. As soon as it reaches the gills, the vampire litusfoi will either wrap its wings around or simply stick to the gills. Once affixed to its host, it will digest some of the skin and consume the blood as it rushes through the gills. The vampire litusfoi will effectively replace the lost epidermis and keep the host from bleeding out. When not attached to a host, the vampire litusfoi can survive by filter-feeding. When attached to a host, the vampire litusfoi will take on a pink color due to the presence of hemerythrin. Those not attached to a host are a dull brown color like that of their ancestor.