THE TWILIGHT ZONE

“Mesopelagic Zone”

We resume our recreational activities on the beach every summer within the shallow area of the ocean. Some people may think the first few meters in the ocean harbors most of the marine creatures due to it being closer to the sun, and their numbers dwindle in the deeper zones. However, the twilight zone is home to more diverse fish than the rest of the ocean combined. It’s the second zone of depth, covering almost all of the world’s open oceans. Yet despite its size, it’s still not well understood by scientists. It’s present in the world’s 5 oceans; Pacific, Atlantic, Arctic, Southern and Indian oceans.

Four ocean zones exist that vary in depth. The region of the ocean that sits on the surface, is called the sunlight zone (Epipelagic Zone), where enough sun rays can penetrate the waters for photosynthesis to occur. The maximum depth for this zone in clear, open ocean water is 200 meters. Here is where the most common fish and exotic plants thrive in large numbers. Next is the twilight zone (Mesopelagic Zone) where barely any sunlight reaches. It extends from around 200 meters to 1000 meters. The environmental conditions become much more extreme and inhospitable for the average being. It is home to very unique fish and invertebrate species, but there are no photosynthesizing organisms here. This means that animals living in this zone either live on food particles that fall from the sunlight zone or are active predators that can go up to feed. Third, is the midnight zone (Bathypelagic Zone), where it’s completely dark and fewer species can survive the freezing temperatures. It is the part of the ocean that extends from 1000 meters to 4000 meters. Lastly, there’s the abyssal zone (Hadalpelagic Zone) that starts from 4000 meters until 6000 meters, which is usually the maximum depth of oceans if no trenches were formed. The word “Hadal” comes from Hades, the ancient Greek god of the underworld. Only a handful of organisms can live in this depth, such as microorganisms, the snail fish and species of shrimps.

There can be however, as mentioned, a fifth zone, which are trenches. The deepest point in the world reaches about 11,000 meters, and that is the Mariana Trench. It’s called the challenger deep and it was explored by the US explorer Victor Vescovo in 2019 for the first time in a new submersible called the Limiting Factor. He witnessed 4 new species and fun fact, he also found plastic and liter…human contamination even reaches the deepest pits of the earth.

Due to the twilight zone’s extreme depths that exceed the safe diving limit, yet not deep enough to invest in making a lot of machinery or submarines to dive down, this region’s mysterious marine life is vastly unexplored. On that note, Ahmed Gabr, an Egyptian ex-army officer now holds the Guinness World Record for diving the deepest depth of 332 meters on September 18th, 2014! He scratched the surface of the Twilight Zone and probably saw creatures no-one has ever seen, with his own eyes.

But with such a long way down to the twilight zone, why should we care what happens to it? Well, humans receive two key benefits from the twilight zone: the removal of heat-trapping carbon dioxide from the atmosphere, and the support of commercially important fisheries in the surface waters. During their daily migration, the creatures of the twilight zone move heat-trapping carbon dioxide from surface waters to the deep ocean, where it can be stored for long periods. Potential future benefits include the harvest of twilight zone fish to produce fish meals for aquaculture operations or fish oil for human health supplements. Society also receives indirect benefits from the twilight zone, such as the knowledge generated by marine science and the environmental awareness of the ocean. For example, this habitat has some of the most ancient creatures on earth, like the Leatherback Sea Turtle, the largest and oldest turtle in the world. It is from the time of the dinosaurs and hasn’t evolved much for over 70 million years

In the deeper parts of the twilight zone, the sea creatures exhibit an extra-ordinary phenomenon called Bioluminescence. As in, they rely on producing and emitting their own light through chemical reactions or bacteria in their body. It’s an adaptation to guide them in the darkness, send distress signals or lure prey. Magnificent species including colorful jellyfish, worms, bacteria, squid and transparent fish all sparkle in the dark and what a scene that is. Most of these lights are blue or green. Little is known as to why that is, but scientists believe these colors travel faster underwater. Red is sometimes produced, but it is a bit dim against the dark water. There’s even a species called Gossamer Worm that emits gold specks all around it.

Sadly, humans are slowly endangering this zone due to invasive fishing nets, that are pulled regularly to the surface to “catch all in its way”. Just the sound of it feels detrimental to the ocean life. We are so invested with life outside the planet that we overlook life beneath our oceans. We’ve got our very own alien life forms here on earth, waiting to be discovered. Marine biologists are slowly beginning to uncover just the basic species that live there, but surely there’s an infinite number of bizarre creatures in our planet’s sea bodies.

It is impossible for divers to dive deeper than 300 meters into the ocean, but with the help of a magical portal, a diver was able to witness some of the strangest creatures that ever lived.