Genus of freshwater copepods, comprising over 400 species, with a single large eye (7)
I believe the answer is:
cyclops
(Other definitions for cyclops that I've seen before include "Mythical creature" , "In Greek myth, one of a race of one-eyed giants" , "A one-eyed giant in Greek myth" , "Fabled one-eyed giant" , "one with limited perception" .)