Metamorphosis in y-larvae (Crustacea Facetotecta). (A) Light microscopy. Lateral view of a juvenile facetotectan (ypsigon stage) after 28 hours exposure to 20-hydroxyecdysone (20-HE), leaving the molted cuticle of the preceding y-cypris stage. The pigment of the degenerating compound eyes is seen anteriorly in the ypsigon. The shield and swimming limbs of the cyprid are left behind. (B) Lateral view of a free ypsigon after escape from its y-cypris 26 hours after exposure to 20-HE. Note the absence of segmentation and limbs. The elongated brownish body may represent the vestigial gut. (C) Dorsal view of free ypsigon disconnected from the empty y-cypris cuticle.