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The irregular pupils in plecos are obvious, however, what purpose does this serve?

Thank you for your thoughtful replies.

The omega factor/optical operculum is used for light intake management.

Yes, the omega iris does allow for plecs to vary the amount of light that enters their eye. It's theorized also that it has the extra purpose of concealing the shape of the normal eye, which helps in camouflage; the eye is an exceptionally obvious part of many animals. IMO, this argument breaks down because not all loricariids have the omega iris. The presence or absence of the omega iris allows the identification of certain genera in Loricariinae, and all members of the small group Rhinelepini lack the omega iris.

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The aquarist is one who must learn the ways of the biologist, the chemist, and the veterinarian.

Shini- as always a great response.

Cup- thank you for your informed response.

You two are great advisors.