![]() ![]() The result? Cloaking shields down.īut after studying seven types of hyperiids, Bagge found one species, Cystisoma, whose legs were covered by extremely tiny structures, called nanoprotuberances. (Think of what happens when you shine a flashlight on a transparent glass window at night.)Īnd that’s what threatens the hyperiids-the light passes through seawater, which has an RI of 1.34, and then collides with the transparent crustacean, with an RI of 1.57. If light smacks into a material with a higher refractive index, the sudden change can create a very bright reflection. So, if water ice has a RI of 1.31, that means light travels 1.31 times faster in vacuum than it does through ice. A measurement called the refractive index (RI) tells us how quickly light travels through various types of materials. Light slows down when passing through anything that isn’t a perfect vacuum. Shag Carpet of the Seaīut Bagge discovered that some hyperiids enhance their invisibility by making use of antireflective coatings. Hyperiids are also vulnerable to certain predators-like the deep-sea dragon fish-that use bioluminescent searchlights to hunt for their meals. “Any reflections that hit you from above are going to make you just flash really brightly against the darker background,” says Bagge. So, even in the open water, transparent hyperiids might have their cover blown by sunlight and moonlight shining down on them, striking at an angle that can make them more visible to predators. Some of the light is reflected back at us, allowing us to see some details, such as shape and size. That’s because when light encounters a transparent object, not all of it passes through. You can, for instance, see a clear drinking glass or a sheet of cellophane. ![]() Although transparency is a nifty camouflage mechanism, it doesn’t render objects completely invisible. Still, Bagge was curious about why these crustaceans are so difficult to see. "You'll just see them floating around, looking for their next meal, and if you're transparent, then it's good, because then you don't have a shadow, you don't have a silhouette," says Bagge. That's a nice trait to have when you're swimming in the open ocean among a lot of fish that have upward-facing eyes. I pulled my hand out of the bucket and it looked like a glass animal.” “I stuck my hand in the bucket to try to reach in and grab something else, and instead I hit something that was hard, but I couldn't even see it. “The first time we looked at what we had caught, there were a whole bunch of animals in the bucket, and I was looking at all these black, scary-looking fish,” she says. ![]() (One species, Phronima sedentaria, is rumored to have been the inspiration for the monstrous alien queen in the 1986 film Aliens.)īagge’s fascination with the invisible animals stems from her own close encounter a few years ago, while aboard a research ship collecting specimens. They’re related to sand fleas, except that they can grow up to seven inches and look much creepier. Aliens Among Usīagge is a specialist on invisible crustaceans-most notably, predators known as hyperiid amphipods. The agile Octopus berrima shows us its getaway moves and camouflage tricks. ![]()
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