At the deepest point in the ocean lives a fish that is pink, slimy, and looks a bit like an oversized tadpole, up to a foot long.

In the Mariana Trench—7,000 meters below the ocean’s surface—these fish makes a living in total darkness and at crushing pressures that can reach 1,000 times more than at sea level.

But the Mariana snailfish is not only abundant in this area; it’s the region’s top predator. How does an animal make a living in such an extreme place? (See "How the Mariana Trench Became Earth's Deepest Point.")

New research provides clues. In a study published in Nature Ecology & Evolution, Chinese researchers examined the anatomy and genetics of the fish. The team picked