There are many living things on the Earth. Among them are plants and animals with wildly unique looks and features that you would not even have imagined. They mostly live in harsh environments, such as the deep sea, or the part of the ocean below two kilometers. This dark place gets very little or no sunlight at all, and the water is cold enough to be close to 0 degrees Celsius.

Additionally, the water pressure down there is incredibly high. At a depth of 10 kilometers, the water pressure is as high as 1,000 atmospheres, which is equal to the force that presses on an area of 1 square centimeter with a weight of 1 ton. Imagine that your entire body is being squeezed under that pressure. We would die in less than a second.

Just 100 to 200 years ago, people thought that there was no life in the deep sea. However, as technology advanced, people began to discover life in this dark, high-pressure environment. In addition, we should realize that there are quite a few different forms of life.

Plants cannot survive in the deep sea because they cannot get sunlight, but animals can adapt to live in their own way. Deep-sea animals feed on the carcasses and excrement of animals and plants that live near the surface and sink into the deep sea. Ecosystems are created near deep sea vents, which use heat and minerals from the Earth's interior.

Deep sea creatures have several common characteristics. Many of them have deteriorated eyes because they cannot see in the dark anyway. Some animals, on the other hand, have large eyes that allow them to see better even in little light. Some have organs that emit light on their own to attract prey or find a mate.

▲Image by: GettyImagesBank

Atlantic football fish, for example, have tentacles on their heads, which emit light from the tips. These were named so since they look like a soccer ball. The pelican eel, which has a much larger mouth than its body, emits light from an organ on its tail to attract prey.

There are more features in the appearance of deep-sea fish. Their mouths are significantly large or they have terribly large teeth.

Their stomachs stretch to accommodate large prey as there is very little food in the deep sea. They have evolved for survival - not to lose the prey they just caught.

Unlike other fish, deep-sea fish have degenerated swim bladders. The swim bladder is an air sac in the body of fish. Fish move up and down in the water by controlling their buoyancy with the air in the swim bladder. Fish without the swim bladder, like sharks, accumulate a lot of oil in their bodies. Fish can float upwards as oil is lighter than water. Deep sea fish also control buoyancy by accumulating oil in their bodies.

Living in such an extreme environment, deep-sea fish may seem strange to our eyes. As most are adapted to high pressure, they die quickly when caught in a net and pulled out of the water. Due to the water pressure, their looks become more bizarre with protruding bodies or eyes.

Not all deep-sea environments are cold. There is a very peculiar environment called the hydrothermal vent, around which many creatures live in an ecosystem. Hydrothermal vents release magma materials from the seafloor. As they emit something that looks like dark smoke, they are also called “black smokers.”

▲Black Smokers(Image by: Wiki Media Commons)

In the warm water near hydrothermal vents, microorganisms live by getting energy from minerals coming out of the ground. Several marine animals, such as shrimp, crabs, and clams, eat or form a symbiotic relationship with these microorganisms. For example, the microorganisms live on the shells of blind shrimp that swim around hydrothermal vents. By doing so, microorganisms can obtain what they need to survive, and blind shrimp feed on the microorganisms.

Looking like an elongated tube, Riftia pachyptila has no digestive system, but instead stores microorganisms in its internal organs. The underwater worm has a symbiotic relationship with microorganisms where they provide minerals, and microorganisms produce and offer energy to Riftia pachyptila.

▲Riftia pachyptila(Image by: Wikimediacommons)

Surprisingly, much of the deep sea remains unexplored. It is difficult for humans to travel under the sea, and only limited areas can be investigated. Nevertheless, we have still been able to discover such rare creatures. There must be more surprising findings if we become able to investigate every nook and cranny of the Earth's deep sea.