Pressure-Proof Bodies

At 4,000 meters depth, pressure reaches 400 atmospheres — enough to crush a submarine not built for the task. Deep-sea creatures survive by eliminating gas-filled spaces in their bodies. Many have no swim bladder.

The snailfish, recorded at 8,178 meters in the Mariana Trench, is one of the deepest-living fish ever observed — though the depth record now belongs to a snailfish filmed at about 8,336 meters in the Izu-Ogasawara Trench. Its body is gelatinous and translucent — essentially a blob of flexible tissue that pressure cannot crush.