Unlike other flukes (trematodes) in which sexes are not separate (monoecious), schistosomes are unique in that adults are divided into males and females, thus, gonochoric. However, a permanent male-female pair, a condition called in copula, is required to become adults; for this, they are considered as hermaphrodites. Male worms are robust, tuberculate and measure 6-12 mm in length. Females are longer (7-17 mm in length) and slender.