Are they parasites though? It may be symbiotic, especially if the relationship between the species has spanned over many years. e.g. their presence may promote the production of rhodopsin.
OTOH it may be natures way of allowing natural selection to take place in the sharks since their lifespan is so long. The wiki article seems to imply that's not the case though.
> These parasites can cause multiple forms of damage to the sharks' eyes, such as ulceration, mineralization, and edema of the cornea, leading to almost complete blindness.
OTOH it may be natures way of allowing natural selection to take place in the sharks since their lifespan is so long. The wiki article seems to imply that's not the case though.