Why Animals Get Creepier the Deeper You Go? | Real Science

The Deep Dark Sea

Not all of the darkest, strangest corners of the universe are in some distant galaxy millions of light years away. In fact, the most mysterious of these dark places is right here on Earth. A place with no sunlight, crushing pressure, and near-freezing temperatures is not the desolate wasteland that one might expect it to be. It is instead populated with a huge variety of life, life that takes shape in ways that our terrestrial minds can barely comprehend.

Some creatures of the deep have enormous, piercing eyes, others have no eyes at all, and others still have eyes inside their transparent domed heads. Others glow for defense or predation, and at these depths where photosynthesis cannot occur, the food chain becomes a little unpredictable. Some creatures typically classified as filter feeders have even evolved to become unlikely, terrifying carnivores. Others become such effective predators that their mouths are bigger than the rest of their entire body or have teeth that pierce the darkness in every direction. From the ethereal to the spooky, the dark sea holds a world of adaptations that jars the imagination, and the deeper you go, the creepier it seems to get.

The Twilight Zone

The uppermost layer of the deep sea is the mesopelagic, aka the twilight zone, and it extends from 200 meters to a thousand meters. A little bit of light still penetrates at these depths, but not much. The very first color to disappear is red because it has the longest wavelength and the least energy of the visible spectrum, and a lot of creatures that spend time in the twilight zone use this to their advantage, evolving to be shades of red that render them practically invisible at these depths. Enter the vampire squid. Catching a glimpse of it in the lights of a submersible, you might understand why it got such a ghastly name. On top of its red skin, it has enormous eyes that seem to glow and spine-like protrusions from its tentacles all give it a far more fearsome look than the cephalopods of shallower waters. But just as its red color seems eerie to us but has a vital evolutionary purpose, so too do its other sinister-looking features. Despite its spooky name, vampire squid are not actually bloodthirsty hunters. Unlike almost all other cephalopods, this creature is a detrivore. It gets almost all of its calories from marine snow.

Marine snow is particulate matter that trickles down from higher up in the ocean and is made of decaying crustaceans, zooplankton, larvaceans, diatoms, and fecal matter.

The vampire squid has four arm pairs with finger-like tendrils called siri plus two long retractable filaments. It sits practically motionless around depths of 600 to 900 meters, slowly collecting marine snow on its mucous-laden filaments and slurping it down. Scientists were surprised to discover that marine snow has a pretty high nutritional value, but the vampire squid still doesn't have a whole lot of energy to expend. They get by thanks to having a suppressed metabolism, much lower than any other cephalopod of a comparable size.

The Big Fin Squid

As you descend deeper, the cephalopods become even more terrifying. The genus Magnapina, or the big fin squid, are thought to be the deepest occurring squid genus with sightings as deep as 6212 meters. This makes the big fin squid the only known squid to occupy the hadle zone, the deepest region of the ocean. Their arms and tentacles can be up to eight meters long and are usually held at disconcerting right angles, the squid giving itself the appearance of having elbows, and its translucent, shimmering mantle makes the creatures seem completely otherworldly.

Little is known about the feeding behavior of these squids. Scientists have speculated that they might use their long arms by dragging them along the sea floor and grabbing whatever edible organisms that they can. Alternatively, the arms might passively grab food such as zooplankton or bits of marine snow. But in an environment without any plant life to form the base of the food chain, being a detrivore is far from the only strategy. In fact, a number of organisms that are herbivores or filter feeders in shallower parts of the ocean become carnivores in the deep sea. That's the case with the predatory tunicate.

The Predatory Tunicate

The predatory tunicate belongs to the acidian family, who are also known as sea squirts, a class of colorful stationary filter feeders that generally live in

Deep Sea Creatures: Adaptations and Fascinating Discoveries

Deep sea creatures invoke creepy feelings in us because they are nothing like the ones we see in our daily lives. Their habitat is so far removed from us that we liken it to the underworld and associate it with fears, secrets, and eternal death. However, every freaky adaptation is something crafted by millions of years of evolution to live in such an unusual environment. Let's explore some fascinating discoveries about deep sea creatures and their amazing adaptations.

Barreleye Fish

Barreleye fish are known for their transparent heads and tubular eyes that are pointed upwards. They live in the twilight zone where there is still a little bit of light available for them to make use of. They can keep their prey in view at all times, even as they snap their body vertically to snatch the food swimming above it. Their eyes can roll forward and see through the front of their heads as well as the top for a maximum arc of 75 degrees. This strange adaptation allows them to hunt effectively when their tiny mouth points in a different direction than their eyes.

Deep-Sea Creatures That Forego Vision

Some deep-sea creatures forego vision altogether, like the tripod fish. Instead of relying on sight, they balance on the sea floor like little tripods and wait for other creatures to swim by. They use their elongated pelvic fins to stretch down to the ground holding the motionless and upright while they use their pectoral fins like hands to reach forward. These fins are filled with enlarged spinal nerves to help them sense the water currents and whatever objects might float their way. In this way, they can sit tight and wait for food to come to them.

The Deepest Fish Ever Found

Recently, scientists exploring a marine trench near Japan found a fish living 8336 meters below the surface, the deepest fish anyone has ever found and is likely to ever find. What they found is a type of hadal snailfish, a translucent scale less tadpole-shaped creature that thrives in a place named after Hades itself. Little is known about this ghostly ethereal fish that lives in complete darkness.

Human Sonar

Human eyesight is one of the most complex biological processes we know of. But what's even more amazing is what individuals who have lost their sight are still able to see. Human sonar allows people without sight to see with sound. Other individuals who lost their sight due to damage to their visual cortex can still complete obstacle courses with no knowledge that they even did so.

Nebula: A Streaming Platform for Educational Content

If you're interested in educational content, Nebula is the place to go. It's a streaming platform made by several educational YouTube content creators, where you can take more risks, upload videos early, and post original content that doesn't necessarily fit on YouTube. There are many original series, such as Becoming Human, which is a passion project about the incredible story of human evolution. Nebula has even produced a feature-length film called Night of the Coconut and a genre-bending award-winning play called The Prince. You can watch them in their entirety on Nebula.