The project that I have enjoyed the most so far has been the anatomy and physiology assignment. I decided to study the pupillary operculum on the banded guitarfish, blue-spotted ray, and clearnose skate. Specifically, I analyzed the ratio between the surface area of the elasmobranchs pupil compared to the area of the operculum covering that pupil. Throughout my research, I saw how the fingerlike structures, coming off the main lobe of the operculum varied depending on the type of environment known to that specimen. For example, the clearnose skate exhibited the most pupil coverage from the pupillary operculum. After acknowledging that the operculum creates multiple holes, and therefore enlarges the field of vision, I realized how that correlated to the deep depths that this skate is usually in. In comparison to the other elasmobranchs, the clearnose skate resides in deeper regions of around 200m. Because of this depth, their pupil needs the most regulation in terms of how much light is let through because of the unclear visibility in their habitat. I suspect that by having more fingerlike structures and an operculum that hangs past the pupil—the field of vision is even more so. This is extremely helpful to the skate since they are found in sandy, harsh conditions.
pupillary operculum of Raja eglanteria, Clearnose Skate Amblyraja radiata, Thorny Skate
I really felt that my research culminated most today when I saw this pupillary operculum in action! The marine immersion team captured a thorny skate by using the trawling method on the back of a boat. Although stressed, this female skate possessed almost identical pupillary operculums to that of the clearnose skate that I sketched and studied. Although not in her natural habitat, it was fascinating to see these regulatory systems applied on a real life specimen. I really hope that more research is done on the pupillary operculum of elasmobranchs. After researching online, I discovered that most research regarding this operculum is done on llamas and horses—not marine species. Now that I am completely enamored with this regulatory system that I’ve even seen in person work so well to benefit the species, I can only wish for further research on these amazing structures!
-Maris Zammataro
Adventures in Marine Science 