sex-determination system ZW sex-determination system https://en.wikipedia.org/wiki/ZW_sex-determination_system https://www.wikidata.org/wiki/Q135752 A chromosomal system that determines the sex of offspring in birds, some fish and crustaceans such as the giant river prawn, some insects (including butterflies and moths), and some reptiles, including Komodo dragons. In this system, female has a pair of dissimilar ZW chromosomes and male has two similar ZZ chromosomes.