If there’s one thing the fish known as Macropinna microstoma doesn’t have to worry about, it’s being hit in the head by a falling brick. Its tube-shaped eyes typically look straight up -- through the transparent top of its own head. But it can also rotate its eyes so they look forward -- through organs that are the equivalent of nostrils.
Macropinna has a transparent head. Credit: 2004 MBARI (Monterey Bay Aquarium Research Institute)Macropinna is found along the rim of the northern Pacific Ocean, from Japan to the Bering Sea to Baja California.
It lives at depths of up to a couple of thousand feet, and it may troll for food in the tentacles of jellyfish. So it needs eyes that can gather a lot of light, but that are protected against the stinging tentacles.
So Mother Nature has come up with a bizarre but apparently effective solution: moveable tube-shaped eyes housed inside a shield that’s filled with fluid. The shield is clear, so Macropinna’s head is transparent.
Scientists used to think that the eyes always aimed straight up -- through the top of its head. But recent observations with a small submarine in Monterey Bay show otherwise. The fish can turn the eyes so they aim straight ahead. In that position, they peer through small structures above the mouth that look like eyes, but are really organs for sensing smell.
With this arrangement, Macropinna may be able to track food as it falls from above. Or it may spot a potential meal above it, then rotate its body to bring its mouth in position to snatch it -- all while keeping its movable eyes right on the target.
