Ommatokoita is a monotypic genus of copepods, the sole species being Ommatokoita elongata.

[1] However, a specimen has been found on the skin of the great lanternshark (Etmopterus princeps), which has been assigned to the genus but not the species.

[2] Ommatokoita elongata is a 30 mm (1.2 in) long pinkish-white parasitic copepod, frequently found permanently attached to the corneas of the Greenland shark and Pacific sleeper shark.

[3][4][5] The parasites cause severe visual impairment, but it is thought that the sharks do not rely on keen eyesight for their survival.

[4] It was speculated that the copepod may be bioluminescent and thus form a mutualistic relationship with the shark by attracting prey, but this hypothesis has not been verified.