Through the large eyes of humpback whales cruising the ocean, the world appears much different from what humans see. For the whales, the world is surprisingly blurrier than expected – and this could have significant implications on the mortality rate of the gentle giants that average between 40 and 50 feet long.
These findings about whales’ vision come from University of Tulsa graduate student Jacob Bolin, who is pursuing a doctorate in biology and conducted the fascinating whale research while working toward his bachelor’s degree at the University of North Carolina Wilmington. His team’s work was published in the journal Proceedings of the Royal Society B in May.
With the opportunity to study the grapefruit-sized eye of a humpback whale, Bolin conducted his undergraduate honors thesis with the goal of learning more about the marine mammal’s visual acuity. According to Bolin, “visual acuity is basically how clear or blurry vision is.” For humans, it is tested when they read the letters off the chart at the eye doctor. Since ocean optometrists are in short supply, Bolin and his team dissected the eye of a humpback whale that had been archived by UNCW’s Marine Mammal Stranding Program in 2011 and took a look at things for themselves.
Knowing that “larger eyes generally have a higher (more clear) visual acuity,” Bolin said, the team was curious whether the trend persisted in large whale eyes. As was discovered, it did not.
“It turned out their visual acuity was an order of magnitude lower (blurrier) than what would be predicted based on eye size,” he said. Bolin explained that there are two factors that measure visual acuity: “the focal length of the eye (the length from the middle of the lens to the retina, which informs focusing power) and the peak density of retinal ganglion cells (which can be thought of as the pixels of the eye where more cells mean more pixels and thus a clearer image).” Using these measurements, Bolin and his team used image modeling to alter an image as a humpback whale would see it.
“What this image modeling showed was that humpback whales are most likely able to see large, silhouetted objects (large school of prey, other whales, etc.) at distance even with their poor visual acuity,” he said. “However, when you model an image of a fishing net, which only appears large if you can distinguish the small details of the netting at a distance, it appears to become unidentifiable from the background to the humpback whale only about two or three body lengths away.” This means humpback whales could unwittingly swim toward certain entanglement, unable to see sinewy fishing nets before it is too late.
Reflecting on his work, Bolin is proud of the attention that his research received, with articles being published about it in The New York Times and Smithsonian magazine. “These findings are a great first step to hopefully one day limit the impact of human activities on humpback whale mortality,” he said.
Bolin has had an interest in marine life and a desire to be a marine biologist since he was young, and he is continuing to conduct research with the hope of making a difference. He is currently working with Alex Kingston, assistant professor of biological science in UTulsa’s Oxley College of Health & Natural Sciences, in her lab studying brain damage in snapping shrimp – the details of which he is excited to share in the future.