Today, NPR published the article “’One of a Kind’ Collection of Animal Eyeballs Aids Research on Vision Problems.” It elaborated on the Comparative Ocular Pathology Laboratory at the University of Wisconsin-Madison. I enjoyed the article because I think that database and sample collection and management could be a fantastic resource for researchers. However, many scientists still shy away from overly collaborative projects or sharing their hard-earned data or resources. I find this rather unfortunate because their resources could potentially make vital contributions to scientific research. Hence, I am always excited to hear about projects that aim to integrate rather than separate. Yes, an eyeball collection is a rather odd topic, but it seems like it is providing a wealth of information for animal- and human-based research. I think that these collections are great because all of the specimens are stored in the same place for easy access, and sometimes research takes unexpected turns. Who knows when you might need a collection of over 56,000 specimens!?
On the subject of eyes, I find the different shapes of pupils fascinating and looked up a few articles to discuss today: Eye Shapes of the Animal World Hint at Difference in our Lifestyles (NPR), Weird pupils let octopuses see their colorful gardens, and Revealed: Why animals’ pupils come in different shapes and sizes. The first and third article are rather similar, but The Conversation article (third one) expands a little more than the NPR article on the topic of cyclovergence. This was my favorite pupil-based fact. Goats, deer, horses, and sheep can rotate their eyes inside of their heads! First off, let me state that these animals have rectangular pupils, and yes, it does look slightly creepy. The article elaborates that by having a horizontal pupil, these animals expand their horizontal visual field. Consequently, these farm creatures increase their peripheral vision, a sense necessary for avoiding predator attacks. (Predators, in contrast, have vertical pupils to give them enhanced forward vision to ambush prey.) That background out of the way, back to cyclovergence. The trippy thing (besides their rectangular pupils) is that goats, deer, horses, and sheep can rotate their eyes so that their pupil is always borderline parallel with the ground! In other words, even if the animals bend their head and neck down to graze, their pupils remain parallel. It is like those unnerving paintings where the eyes seem to follow you no matter where you walk in the room. Maybe they studied painting around farm animals!
The other wonderfully weird pupils that I will touch on belong to octopuses, squids, and cephalopods. Although these animals have been categorized as colorblind, their bizarre pupil shapes may actually allow them to distinguish various colors. The wide U- or W-shaped pupils of these sea creatures means that they receive more “chromatic aberration.” Having a more dilated pupil means that the light (and consequently colors) hitting the retina are more spread out. As a result, the image sent to the brain is blurry, but it also has colorful fringes around objects in the field of vision. Most animals evolved to have sharper vision, but it seems that cephalopods valued color recognition and discrimination higher than sharper vision. Therefore, we have animals that should only be able to see in black and white. However, they have discovered a sneaky loophole to keep their lives colorful and help them camouflage from predators, as well as produce effective mating displays. Many other fantastic pupil shapes exist, but I do not have time to fit them all in one post! Maybe in the future… I hope that you still got your anatomy/sensory/biology fix of the day! I leave you with a picture of my favorite critter, Ollie, my one-eyed cat. She might be missing an eye, but she has all of her whiskers! She is also a great example of the vertical pupil shape that is characteristic of predators!