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The principal eyes of jumping spiders (Salticidae) integrate a dual-lens system, a tiered retinal matrix with multiple photoreceptor classes and muscular control of retinal movements to form high resolution images, extract color information, and dynamically evaluate visual scenes. While much work has been done to characterize these more complex principal anterior eyes, little work has investigated the three other pairs of simpler secondary eyes: the anterior lateral eye pair and two posterior (lateral and median) pairs of eyes. We investigated the opsin protein component of visual pigments in the eyes of three species of salticid using transcriptomics and immunohistochemistry. Based on characterization and localization of a set of three conserved opsins (Rh1 - green sensitive, Rh2 - blue sensitive, and Rh3 - ultraviolet sensitive) we have identified potential photoreceptors for blue light detection in the eyes of two out of three species: Menemerus bivittatus (Chrysillini) and Habrocestum africanum (Hasarinii). Additionally, the photoreceptor diversity of the secondary eyes exhibits more variation than previous estimates, particularly for the small, posterior median eyes previously considered vestigial in some species. In all three species investigated the lateral eyes were dominated by green-sensitive visual pigments (RH1 opsins), while the posterior median retinas were dominated by opsins forming short-wavelength sensitive visual pigments (e.g. RH2 and/or RH3/RH4). There was also variation among secondary eye types and among species in the distribution of opsins in retinal photoreceptors, particularly for the putatively blue-sensitive visual pigment formed from RH2. Our findings suggest secondary eyes have the potential for color vision, with observed differences between species likely associated with different ecologies and visual tasks.
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Ethanol-preserved eyes provide ocular and retinal predictors of natural morphological conditions in scallops: a case study with Argopecten irradians (Bivalvia: Pectinidae)
usp.br Ethanol-preserved specimens represent one of the most common resources for biological research. However, little is known of how ethanol preservation may change tissue morphology and impact the interpretation of trait quantification in structures, such as eyes. While scallop eyes are an interesting system for investigating eye evolution and visual adaptations, cross-species comparisons mainly depend on museum specimens. Therefore, to test whether ethanol-preserved specimens serve as accurate indicators of natural eye morphology, we investigated the effects of preservation on selected traits, such as eye and pupil diameter, in the scallop Argopecten irradians . We also compared ethanol-preserved eyes to paraformaldehyde (PFA)-fixed eyes to investigate possible impacts on retinal morphology. Our results demonstrate that eye size does not change with short-term preservation, whereas pupil size becomes significantly larger, likely due to the contraction of actin fibers during dehydration. When comparing measurements among eyes and treatments, eye size correlates to pupil size, but is not correlated to body size. We found that ethanol-preserved eyes provide close estimates of retinal traits, with similar photoreceptor spacing distance and number of photoreceptor cells, compared to samples fixed in PFA. These findings might also be applicable in the context of other mollusks, especially bivalves and gastropods, with delicate visual systems. Our study provides evidence that ethanol- preserved eyes exhibit tissue-specific differences that should be acknowledged in morphological studies. For example, pupil size should be investigated while accounting for post-preservation effects. Other traits, such as lens shape, are inconsistent and severely impacted by preservation. Finally, eye size and some photoreceptor cell measurements can be helpful to describe natural morphology.
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- Award ID(s):
- 2148203
- PAR ID:
- 10613283
- Publisher / Repository:
- Oxford University Press
- Date Published:
- Journal Name:
- Journal of Molluscan Studies
- Volume:
- 90
- Issue:
- 5
- ISSN:
- 0260-1230
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.1093/mollus/eyae044
