There lies in the ocean an unseen world that is filled with creatures beyond the imagination. It lies 660 to 3,300 feet below and is known to scientists as the twilight zone. Not much research has been done on this layer of the ocean, but it is believed that there are more animals here than anywhere else in the world.

There’s a group of scientists currently studying this area’s bizarre inhabitants and they are hoping their research can help find a more sustainable approach to the surface’s fisheries.

Creatures Beyond Science-Fiction

The ocean’s creatures are unique compared to those on land because they each hold their own auditory signature that our ships can detect using our own sound waves. The animals that reside in the twilight zone are also known to produce their own light through different chemical reactions.

This light helps them blend in with the light flowing from the surface. Hatchet fish use this technique called counter-illumination to hide from predators looking for their silhouettes from below. Other animals down here may turn their eyes into giant lenses (like how our eyes adjust to light) or even opt to use other senses instead like the Fangtooth. The Fangtooth is known to bump into objects and other fish using pressure sensors on the sides of its body.

The Great Migration

Biologists have known about a vertical migration since the 1800s because their sample nets seemed to come back fuller at night than during the day. The size of the migration wasn’t discovered till World War II when the Navy sailors detected what they called a “false bottom” on their sonar screens.

The “false bottom” was later named the deep scattering layer as it occasionally rose toward the surface each night and sank again the next morning. This layer is produced when sound waves reflect off gas-filled swim bladders or fat droplets within the migrating creatures. This daily migration is one of the largest in the world and it happens every day. Every night creatures from the dark come to the surface just to return to the depths in the morning.

What is the point? Why travel such long distances every single night? The simple answer is food. They do it for survival, but it also helps our planet regulate climate change.

Helping The Earth’s Climate

The creatures that reside in the twilight zone are very small which is very important in an environment like this since small things don’t eat as much. However, when these organisms travel to the surface at night they will often eat the plant material there before traveling downward.

The plant material they eat consists of a large amount of carbon and through the organism, it gets transferred from the surface to the ocean depths. The animals from the twilight zone will then recycle the carbon they collected as feces, breath it out as carbon dioxide, or just turn it into dissolved organic carbon. This entire process has helped the planet regulate the amount of carbon dioxide that exists in our atmosphere. It’s just another important piece to the giant carbon cycle puzzle.