![]() Navy is looking for new ways to cloak and hide submarines and other vessels in open water. This would reveal whether polarization is even useful as a camouflage for fish like the lookdown.īut Cummings and the scientists she worked with aren’t just interested in learning about fish. Still, he argues, these fish are “not by any means invisible.”Ĭronin says researchers should next investigate whether the kinds of high-speed predators that hunt these shiny fish - like marlin, tuna and mahimahi - have vision that can deal with polarized light. And the difference in contrast provided by the reflectivity is relatively small, he says. Thomas Cronin, a visual ecologist at the University of Maryland, Baltimore County, says the fact that shiny fish are camouflaged in polarized light has been known for a long time. “It’s at those direct views that the fish also does a fantastic job at minimizing contrast,” Cummings says. From that angle they would be in full view of a predator. But they were surprised to find that the fish also had good camouflage when viewed from the side. These are the “chase angles” - the positions from which a predator would most likely approach. (That angle is about half the size of the inside angle of any corner of a square.)īased on earlier laboratory research, the scientists had suspected that fish would be well hidden at chase angles. The result? The fish were camouflaged most effectively when being looked at from an angle of about 45 degrees in every direction from the tail or head. This changes how the body reflects light. Their platelets are strategically placed on different parts of the body, the researchers found. These are environments that have less polarized light than the open ocean.īut open-ocean fish are not camouflaged evenly. They were also better camouflaged than the other three species, which lived either in reefs or near the water’s surface. And it helped them blend into polarized light much better than the mirror reflections did. Platelets on these fish reflected polarized light. The other was the bigeye scad, a tropical species that has a blue-green or green back and white belly. One was the lookdown, a silver fish that swims in the Atlantic. Of the five species they studied, the two open-ocean fish had the best camouflage. Researcher Molly Cummings measures fish camouflage with a video polarimeter in the ocean off Curacao. ![]() Then they took pictures of the fish from more than 1,500 different angles. The team used netting to hold a fish in place on an underwater platform against a mirror. This is a camera that lets scientists see polarized light as fish do. To find out, Cummings and her colleagues built a video polarimeter (PO-lar-IM-eh-ter). They wondered if some fish might also have evolved a way to blend in to these light patterns. Biologists have long known that many ocean animals could detect changes in polarized light. That means the light is scattered in a specific pattern, with all the light waves moving along the same plane. But much of the light beneath the ocean’s surface is polarized. She also is a co-author of the new study.įor many years, scientists thought fish camouflaged themselves by reflecting light in the same way a mirror does. ![]() She is a biologist at the University of Texas at Austin. And they are so small that 100 could fit in a grain of sand! “It’s why fish seem so shiny and reflective,” says Molly Cummings. These platelets look like thin, flat crystals. Some species of fish have microscopic structures called platelets in their skin and scales. Understanding how it works may let scientists and engineers develop new forms of ocean camouflage. But some may have evolved a kind of natural invisibility cloak that helps them hide in plain sight. Fish that swim in the open ocean have nowhere to hide from hungry predators.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |