Ipnops

The unusual flat structures on the top of an Ipnops fish's head are highly modified, bioluminescent organs that have completely replaced traditional eyes. They lack lenses and retinas, instead functioning as glandular organs that emit a faint light. This bioluminescence is used to detect the shadows of prey swimming above them against the faint downwelling light of the deep sea.

Ipnops fish are abyssal residents, typically found at extreme ocean depths ranging from 3,000 to 5,000 meters (9,800 to 16,400 feet). They belong to the family Ipnopidae, which is well-adapted to the immense pressures and total darkness of the abyssal plain. At these depths, they rely heavily on their specialized head organs to sense their environment.

As predatory ray-finned fishes, Ipnops feed primarily on small crustaceans and tiny swimming invertebrates that drift through the deep water column. Because food is extremely scarce in the abyssal zone, they likely remain relatively motionless to conserve energy, waiting to ambush prey that swims overhead. Their modified head organs allow them to detect these passing meals.

Yes, Ipnops are considered functionally blind because they lack typical eyes with lenses or retinas that form images. Instead of relying on vision to navigate, they use their modified head organs to sense faint changes in light. This evolutionary adaptation allows them to survive in the pitch-black environment of the abyssal ocean.