Surviving Even After 5 Years of Starvation, Armored Snails... TOP 5 Unknown Deep-Sea Creatures

Pitch-black darkness where not a single ray of light enters, and immense water pressure that weighs down on the eardrums. The deep sea, which remains an unknown territory to humanity, is considered one of the worst environments for life to exist. However, even in these extreme environments, there are creatures with survival methods that defy common sense. In the YTN Science program 《If? Rank!》, Dr. Kim Dong-seong of the Korea Institute of Ocean Science and Technology and science communicator Science Dream appeared to reveal the wondrous survival strategies of deep-sea creatures.

The Secret of the 'Giant Isopod' That Can Endure 5 Years of Starvation

The amazing survival capability of deep-sea creatures has also been specifically revealed through recent research. The presenters cited a creature called the 'Giant Isopod,' which is similar to a large pill bug. There is a case where they survived for as long as 5 years without eating anything from their first meal in 2019 until 2024. This transcendental survival can be summarized into two reasons.

The first is the change in physical structure. Their stomachs are so large that they occupy about one-third of their body, allowing them to consume and store a massive amount of food once they find it, and then consume it slowly. The second is a genetic factor. A gene called 'ND1' obtained from bacteria plays a role in lowering the activity of mitochondria in the cold deep-sea environment. Mitochondria are organelles that use oxygen to produce energy, and by artificially lowering this activity, they can reduce their metabolic rate to save energy extremely and endure for a long period.

'Chemosynthetic Ecosystems' Living Without the Sun and Hydrothermal Vents

The unique appearances of deep-sea creatures are the result of environmental adaptation. In the aphotic zone (depths below 1,000m) where there is almost no light, eyes become abnormally large to detect even the tiniest bit of light, or conversely, eyes degenerate. Also, to save energy, they may have jelly-like bodies instead of muscles and skeletons. In the dysphotic zone between 200m and 1,000m, individuals with large eyes are advantageous to receive faint light and can quickly capture the bioluminescent signals of others.

Particularly noteworthy is the ecosystem around 'hydrothermal vents.' In the past, scientists believed that all living things on Earth lived by depending on solar energy, but this common sense was broken when hydrothermal vents were first discovered at the Galápagos Rift in 1977. Hydrothermal vents are places where chemicals such as hydrogen sulfide, hydrogen, and carbon dioxide are emitted from inside the Earth. Here, sulfur-oxidizing bacteria oxidize hydrogen sulfide to obtain energy, and through this, they produce organic matter. This process is called 'chemosynthesis,' and deep-sea creatures live by depending on this ecosystem formed based on chemical energy instead of sunlight. It is as if two massive ecosystems—the solar-powered ecosystem of the sky and the chemosynthetic ecosystem of the ocean floor—coexist.

TOP 5 Unknown Deep-Sea Creatures: From the Alarm Jellyfish to the Armored Snail

The list of deep-sea creatures selected by the cast exceeds human imagination. 5th place is the 'Atolla jellyfish.' This jellyfish, a species of the genus Atolla, emits blue light in a circular pattern from its umbrella-shaped body part when it feels threatened. This is like sounding a theft alarm, and in English, it is called the 'Bubbler alarm jellyfish.' It is a strategy to use light as an SOS signal to confuse predators or to call in larger predators to protect itself.

4th place is the 'Scaly-foot snail.' This snail is clad in an iron armor made of 'iron sulfide' that is strong enough to attract magnets. Bacteria in its body produce hydrogen sulfide and react it with the surrounding iron components to form a hard shell. Uniquely, having extremely degenerate digestive organs, they live by directly absorbing the organic matter synthesized by the bacteria in their bodies. This species was first discovered in the Indian Ocean at Kairei in 2001, and it was also confirmed during an exploration at a depth of 6,500m through joint research involving Dr. Kim Dong-seong of the Korea Institute of Ocean Science and Technology.

3rd place is the 'Magnapinna squid' with giant fins. Discovered at a depth of 6,212m in 2022, this creature has very large fins compared to its body and has eight arms and two tentacles. At the ends of the tentacles, there are long, thread-like filaments that stretch about 1,000m to 4,000m. It is a species that holds the mysteries of the deep sea to the extent that there has not yet been a case of collecting an adult. Deep-sea exploration uses manned or unmanned submersibles (HOV, ROV), but it is so difficult that the ratio of observing the seafloor is not even 0.001%. In particular, when collecting moving creatures, a suction sampler mounted on a robot arm must be used, and the probability of doing so is very low.

2nd place was mentioned as the 'Giant tube worm,' which has no mouth, anus, or digestive tract. This creature, first discovered in 1977, has a history where specimens were stored in vodka due to a lack of expectations regarding deep-sea creatures at the time of collection. They live by depending entirely on the nutrients made by symbiotic bacteria inside their bodies that burn sulfur. In the early stages, they may have a mouth and anus, but they show a habit of degenerating the digestive tract once the bacteria settle in the body.