Ethanol-preserved eyes provide ocular and retinal predictors of natural morphological conditions in scallops: a case study with Argopecten irradians (Bivalvia: Pectinidae).

This article investigates how preservation in 95% ethanol affects the morphology of scallop eyes, specifically in the species Argopecten irradians, to assess the reliability of museum specimens for morphological and evolutionary studies. The study found that while overall eye size remains unchanged after short-term ethanol preservation, pupil diameter significantly increases, likely due to dehydration-induced contraction of actin fibers. Histological comparisons between ethanol-preserved and paraformaldehyde (PFA)-fixed eyes showed similar photoreceptor spacing and cell numbers, indicating ethanol preservation can yield reliable retinal measurements, though some structures like lens shape are inconsistently affected. These findings suggest ethanol-preserved scallop eyes can provide useful morphological data for research, but caution is needed when interpreting traits sensitive to preservation effects, such as pupil size.