Definitions

Sense organ on upper side of head in many branchiopods.
(syn. neck organ) [Moore and McCormick, 1969]
(Taxon-specific: Class Branchiopoda) Sense organ on upper side of cephalon.
(syn. neck organ) [McLaughlin, 1980]
(Taxon-specific: Order Cladocera) Frontal organ. [Stachowitsch, 1992]
(Taxon-specific: Order Notostraca) Dorsal organ. [Stachowitsch, 1992]
(Taxon-specific: Order Anostraca) Unpaired median sensory organ located on dorsal surface of head; visible beneath cuticle.
(syn. neck organ) [Stachowitsch, 1992]
(Taxon-specific: Subclass Copepoda) Organ associated with specialised areas of modified integument, possibly with osmoregulatory function, typical of fresh and brackish water taxa. [Boxshall and Halsey, 2004]