Ocular lesions associated with attachment of the parasitic copepod Ommatokoita elongata (Grant) to corneas of Greenland sharks, Somniosus microcephalus (Bloch & Schneider)

The eyes from six Greenland sharks, Somniosus microcephalus (Bloch & Schnei der), infected with the parasitic copepod Ommatokoita elongata (Grant) were collected in the Arctic waters of Victor Bay, North-west Territories, Cana da, for study. Transformed adult female copepods, one per eye, were firmly attached to the corneas by an anchoring structure (i.e. the bulla) and each bulla was associated with an opaque area on the cornea. Two eyes additiona lly had one O. elongata copepodid attached to the cornea via frontal filame nts with bullas which were each associated with a small corneal opacity. In addition to opacities associated with copepods at the time of collection, there were several randomly distributed, small, round-to-irregular, full-th ickness corneal opacities which were not associated with copepods. Two unfi xed eye lenses grossly examined in the field were normal in appearance. His tologically, corneal epithelial ulceration and heterophilic keratitis, disr uption, mineralization, and detachment of Bowman's membrane, thinning, diso rganization, mineralization and fibrosis of the corneal substantia propria, and focal thinning and mineralization of Descement's membrane were observe d. Mild heterophilic and mononuclear anterior uveitis was also present. Bas ed on the present observations, it is concluded that parasitism by O. elong ata could lead to severe vision impairment (possibly including blindness) i n Greenland sharks. However, the otherwise healthy appearance of the infect ed sharks studied and the information contained in the literature suggests that O. elongata infections do not significantly debilitate the hosts.