Apparently, “Star Wars: The Rise of Skywalker: 3D," was not playing.
Cuttlefish were outfitted with special glasses in a tank at the Marine Biological Laboratory in Woods Hole, then shown a 3D movie of tasty shrimp on an underwater screen: They lashed out at their prey as if they had been fooled by the images, indicating that they have depth perception, researchers said.
The University of Minnesota-led team’s results were published Wednesday in the journal Science Advances. Cuttlefish are only the second invertebrate species shown to be able to see in 3D, researchers said.
The research clearly establishes that the diminutive cephalopods use stereopsis, or depth perception, when hunting, said Trevor Wardill, assistant professor at the University of Minnesota’s Department of Ecology, Evolution and Behavior.
Wardill, whose lab focuses on how the visual systems of insects and cephalopods process information and generate behavior, said putting the 3D glasses on the cuttlefish with a bit of glue and Velcro wasn’t always easy.
“Some individuals will not wear them no matter how much I try,” he told The New York Times.
Once the glasses were on the European cuttlefish Sepia officinalis, researchers showed them 3D images that made it appear shrimp were in front of the screen. The cuttlefish backed up so they could deploy their tentacles, which they use to subdue their prey before biting them and injecting them with toxins.
The cuttlefish "moved their body away from the screen and shot tentacles at a perceived location,” Wardill said in a telephone interview.
When researchers showed images that made it appear the shrimp was behind the screen, he said, “They would run into the screen trying to get the shrimp behind the screen.”
Researchers said that when only one of a cuttlefish’s eyes could see the shrimp, it took longer for it to position itself for attack. Having stereo vision could thus make a big difference in catching a meal, they said.
Wardill noted that the MBL was “instrumental in helping us get this to work.” He also said researchers had been inspired by similar research showing that praying mantises have stereo vision.
“The evidence presented here,” the study said, “establishes that cuttlefish make use of stereopsis when hunting and that this improves hunting performance by reducing the distance traveled, the time taken to strike at prey, and allowing it to strike from farther away. Further investigation is required to uncover the neural mechanisms underlying the computation of stereopsis in these animals.”
Wardill said cuttlefish actually do better than humans in dealing with depth perception in an environment where there’s a lot of variation in brightness and may have “evolved a more advanced version of stereopsis.”
“While cuttlefish have similar eyes to humans, their brains are significantly different,” Paloma Gonzalez-Bellido, assistant professor at the University of Minnesota and a coauthor of the study, said in a statement. “We know that cuttlefish brains aren’t segmented like humans. They do not seem to have a single part of the brain -- like our occipital lobe -- dedicated to processing vision."
However, she said, "Our research shows there must be an area in their brain that compares the images from a cuttlefish’s left and right eye and computes their differences.”
“This study takes us a step further toward understanding how different nervous systems have evolved to tackle the same problem,” Rachael Feord, a graduate student at Oxford University, the research paper’s first author, said in the statement. “The next step is to dissect the brain circuits required for the computation of stereopsis in cuttlefish with the aim of understanding how this might be different to what happens in our brains.”
Material from Globe wire services was used in this report.
Martin finucane can be reached at email@example.com