Leechusfoi
The leechusfoi split from vampire litusfoi that progressed from easily sucking blood from exposed gills to making more active attacks. They feed, much like their ancestor, by sticking to their hosts and dissolving its skin where it touches. Indeed, its digestive enzymes have become stronger. It will then steadily absorb blood from its new location, turning a bright pinkish-violet color. They can only feed on hemerythrin, but this has allowed them to expand their repertoire to astergnathids and devorator descendants, though in the latter case, the armor makes them very difficult to feed on. Leechusfois can feed in the gaps between plates on vellicator and its relatives, but the mailclad devorator is nearly impregnable.
A well-fed leechusfoi can bud off gametes, containing half its genetic material, which resemble smaller versions of winged litusfoi. These will swim off and find another gamete to merge with, forming a leechusfoi.