The functional and comparative morphology of the photoreceptors of the copepodid larva of the salmon louse Lepeophtheirus salmonis (Kroyer, 1837) (Crustacea : Copepoda, Caligidae)

Citation

Bron J & Sommerville C (1998) The functional and comparative morphology of the photoreceptors of the copepodid larva of the salmon louse Lepeophtheirus salmonis (Kroyer, 1837) (Crustacea : Copepoda, Caligidae). Zoologischer Anzeiger, 237 (2-3), pp. 113-126.

Abstract
The ultrastructure of the optic and extra-optic photoreceptors of the copepodid larva of the caligid copepod Lepeophtheirus salmonis (Krøyer, 1837) is described. The optic photoreceptor comprises a median nauplius eye consisting of two lensed dorsolateral ocelli and a single unlensed ventral ocellus. The dorsolateral ocelli each comprise 9 retinula cells whilst the ventral ocellus comprises 10 retinula cells. All ocelli are bounded by a capsule of conjunctival cells and the entire nauplius eye is surrounded by pigment cells except for two fixed apertures lying above the anterodorsal lenses. An extraoptic photoreceptor is described for the first time in caligids; each bilateral organ comprises two cells resembling retinula cells and is located in the anterior cephalothorax. The functional significance of the photoreceptors is discussed and theoretical abilities compared with known behavioural responses.

Keywords
nauplius eye; ultrastructure

Journal
Zoologischer Anzeiger: Volume 237, Issue 2-3