In the open ocean, there's nowhere to hide. Being visible isn't safe for animals that live here. So many of them take up a remarkable form of camouflage: they're transparent.
Transparent animals let light pass through their bodies the same way it passes through a window. These animals usually live between the surface of the ocean and a depth of about 3,300 feet (1,000 m) — as far as most light can reach. Most of them are extremely delicate and can be damaged by a light touch.
How does an animal become see-through? The objects around you are visible because they interact with light. But a transparent object doesn't interact with light, at least not very much. To become transparent, an animal needs to keep its body from absorbing or scattering light. According to Sonke Johnsen, a marine biologist and professor at Duke University, avoiding absorption is actually easy. Living materials allow light to get through them if they don't have pigments, which are chemicals that absorb specific colors of light. Pigments make your blood red and plant leaves green, but if an animal doesn't have them, its tissues won't absorb light.
__________ Light bends and scatters when it goes through different materials of an animal-skin, fat, muscle, and more. All that bending means light can't pass straight through the animal, so the animal is visible. Transparent animals use different tricks to fight scattering. Some animals are just very small without much tissue to scatter light. Others build a large, clear mass of non-living, jelly-like material and spread themselves over it. Actually the living tissue of the animal is pretty thin.
Eyes and stomachs are hard to hide. To keep enemies from seeing their eyes or their last meal, transparent animals use disguises. Eyes might be placed far away from the rest of the body. A stomach may be covered by something like a mirror which makes others only see the ocean around the animal. It may also take strange, needle-like shape that is difficult to see the edge.
