16 Fantastic Sea Creatures You Never Knew Existed

Some of these sea creatures are beautiful, while others are the scariest things we've ever seen...

Not long ago, people couldn't go deep underwater because we didn’t have good enough technologies that would allow us to survive the enormous pressure, a lack of oxygen, and total darkness. Year after year, more and more scientists become interested in underwater studies. They started to believe that even in one of the most dangerous places on the planet, interesting creatures could be found.

And they were right! When they saw deep underwater animals and other organisms for the first time, oceanologists were shocked. These organisms looked completely different from what they have ever seen. After all, some oceanologists even thought that these beings were aliens from other planets who were preparing to attack us from the depths of the ocean ... yes, that's how out of this world these animals look.

Even today, we know less about our own oceans than about surfaces of other solar system planets, so we still have lots of things to learn about the deep sea.  Even with our limited technologies, oceanologists were able to discover and learn a lot about the 16 fantastic sea creatures listed below.

16 Humpback Anglerfish


This fish lives at least two kilometres below the surface and hunts other organisms by attracting them with an antenna-resembling organ on the head. In the deep underwater, there is no light, so other creatures become attracted by this light and swim closer, but by the time they understand that it’s a trap, it’s already too late.

Their favorite targets are small fish and many strange deep underwater animals that can’t protect themselves. Humpback anglerfish create a white light by using the antenna chemical reactions that result in creating a blue light.

One more interesting detail about their species is that males and females look and live completely differently. In the above picture, you see how a female looks, while males are many times smaller and only needed for reproduction because they are too weak to survive without females.

So, females are like protectors and hunters of food, while males just companions for reproduction.

15 Stargazer Fish


You can find this fish in more shallow waters waiting for prey to arrive but perhaps you wouldn’t be able to see it because they bury themselves in the sand and without movement - waiting for the right moment.

When a small animal comes closer hoping to find food, a stargazer fish kills the prey with its sharp teeth. As stargazer fish live in shallow areas, they find more targets than those animals who live deeper underwater. Why? Because many water animals prefer to live closer to coasts, as there is more sunlight and nutrients coming from the soil. Because of the extra nutrients, more animals can live in less space in the shallow areas.

Stargazer fish uses these benefits and, while still living in the sand, it benefits from getting more food, as this organism has a faster metabolism. This means that stargazer fish needs more food than most underwater animals.

14 Giant Spider Crab


There are animals that don’t hunt or fight against other animals at all. One of such examples is the giant spider crab. While they are bigger than most crabs and other deep underwater creatures, they don’t use their size for fights.

The reason why they became so big is because they need to travel far distances in short amounts of time. By being fast and flexible, they are able to come first to the places where sea creatures die and use them as food.

They live at least 300 meters underwater, in a good place to get a little bit of sunlight and find more dead animals. Also, giant spider crabs are believed to be the largest crabs in the world. After all, they measure up to 4 metres from claw tip to claw tip.

While they are big, their metabolism is slow and allows them to survive many days even if they can’t find food.

13 Giant Squid


Long ago, there were many myths among sailors and coast-living people that believed that if they would travel too far from a coast, a giant squid would eat them. However, these old myths give some real details.

Researchers found that many species of squids can grow much larger that those that live closer to the sea level. Furthermore, they discovered the remains of squids that were as much as 15 meters in size. If we could find such big squids, maybe even bigger squids await us in the future?

After all, in the past, there lived many more large animals. Dinosaurs, mammoths, and maybe even giant squids could have die as the result of too little food to survive. For instance, herbivorous dinosaurs could eat the whole day. That says they needed a lot of food to stay alive. This could be the same situation with super giant squids as well.

12 Megamouth Shark


One of the biggest and strangest sharks ever found was discovered in 1976 and only 50 specimens have been found so far. No matter how rare they are, they're as big as five and a half metres in size, and experienced perhaps the least amount of evolutionary changes from all shark species.

One of the most important details that makes them look different from other sharks is their megamouth. It’s so big that allows megamouth sharks to hunt and protect themselves from much bigger animals.

They don’t necessarily need to hunt big animals to survive as planktons work for them as a good dietary source. Megamouth sharks attract planktons by using a glowing light that is inside of the mouth. Such qualities make them much more capable of surviving than other sharks, but the question is: if they are so good at surviving, why there are so little of them?

11 Benthic Chenophores


They are transparent invertebrates that use their cilia to swim through the water. However, some species of benthic chenophores can’t swim at all because they don’t have cilia. They use their mouth to walk on the sea floor when they need to change their living place. It’s a slow method of moving but it's good enough for them because most often prey that is looking for food swims nearby the seafloor and is easy to catch.

Depending on their species, they use different tactics to get food. Some are able to catch food with their long tentacles, others use their transparency and camouflage skills and wait for a prey to arrive. While others chose to cling to the bodies of a starfish and use their nutrients for their own survival.

The last method is called the parasitic one. It’s when one organism, this time benthic chenophore, benefits from this relationship, while a starfish becomes weaker as it loses nutrients.

10 Hooded Nudibranchs


Some deep underwater animals are so strange that they don’t even resemble animals. They look more as if they were a mix between plants and some sort of a trap. A good example of this is a hooded nudibranch that opens a massive mount to catch small fishes, with its big tooth resembling sticky tentacles.

They are good hunters as they are transparent and, by clinging to seaweed, become invisible to small victims that go into this “living trap." What’s more interesting is that when you pull one of these creatures from the water, they smell like flowers, but if you don’t want to get hurt, it’s better to leave them and buy real flowers.

Most often, they live in warm and quiet oceans that are less inhabited by other sea creatures. However, a hooded nudibrach doesn’t need much energy and nutrients to survive, as most of his body is made from water, so even a rarely caught prey is enough to feel full.

9 Helmet Jellyfishes


These creatures have a strange habit of swimming while holding their stiffer tentacles in front of them, rather than behind, to capture small fishes and then absorb them into their primitive digestive systems. Also, their purple coloration makes them invisible to predators, even when eating bioluminescent victims (those creatures who can emit light from their bodies).

Usually, they avoid light and live up to 1 kilometre below the water surface. Huge numbers of their population can show themselves at night and even become invasive pests off the coasts. Some invasions became such influential happenings among local people that they even created mystical legends about these animals.

But most often, they don’t attack people because they don’t recognize us as their enemies or food. Unless someone starts to attack them, then they, as all other animals, respond and protect themselves and their group members.

8 Xyloplaxes


One of the most unexpected finds by scientists are xyloplaxes that live deeper than sunlight can reach. By their form, they resemble tiny cookie shapes and are close members of the starfish family, as most of their DNA is the same.

What’s more interesting about them is that they eat nothing unless it’s made from wood. Trees, chairs, tables, and branches are okay for them as long as they have wood, which can be found in deep underwater corners more often than you could expect.

Due to storms, many wooden objects sink so xyloplaxes have lots of tasty wood to eat. After they eat a wooden object, they float through oceans until finding something else wooden to eat. If they have plenty of food, their population can skyrocket in a few days. If not, population growth stops and, after a longer period of time, starts to die off.

7 Pterotrachea


A transparent animal with strange eyes, and a trunk on its head is another interesting creature from the deep oceans that is called a “sea elephant."

While most snails living on the ground are slow and inflexible, that's not how pterotracheas are. They are fast predators that, with their brilliant vision, easily spot even the smallest prey and catch them with their trunks. If you can’t remember how they look, just know that they swim as if they were flying, and you’ll be able to recognize them.

Moreover, if they eat something, you can see the prey inside of this creature, as it’s almost completely transparent.

Their transparency is the result of a huge percentage of water in their bodies that is only coated with a thick layer of skin resembling stuff. Most often, they are found in places where the sun can’t reach.

6 Ramisyllis Multicaudata


One of the strangest animals by its form is ramistllis multicaudata, which looks like a reversal of the mythological hydra. It has lots of winding bodies that branch off one another but has just one head and is a lot smaller than a mythological one. The head is at the centre of this animal while its smaller additional bodies spread throughout the tunnels of the sponge host.

They are found in very deep corners of the oceans and only eat animals that are smaller than themselves or any dying organic matter they can find. Most often, not everything is eaten by underwater animals that live close to the sea level. So, it means that tiny organic particles fall deep in water and become as additional food to ramisyllis multicaudata.

5 Dolphin Barnacles


Using a filter-feeding type of eating to survive, flexible dolphin barnacle creatures can be found attached to fast-moving dolphins. Similar to their organisms, they are small and difficult to get rid of so they can live for many days and even months on other organisms.

However, dolphin barnacles are special because most of their relatives are less flexible and attach themselves to slow animals, like whales and turtles. By using their thickly anchoring organ, they attach themselves deep into dolphin’s flesh and use their energy and nutrients for their own survival. The only problem is that they have to travel everywhere where dolphins go.

Furthermore, if dolphin population decreases, dolphin barnacles don’t somewhere else to live so they start to die off. It’s the primary weakness of parasitic organisms. They thrive only if they find animals to use as their host.

4 Stalked Jellyfish


This group of jellyfish has given up swimming and changed their eating habits closer to their far coral and anemone cousins. Due to this animal form, that more resembles some sort of plant, they are capable of waiting a long time in the same place for a prey to arrive. Then, they catch it with its short, muscular arms and eat it with the always open mouth.

When stalked jellyfishes want to change their living place, they walk end over end from its stem to its arms. If it’s too huge distance to travel, they detach themselves and float in the water until they reach a needed place.

These traveling techniques allow them to find new places that are not only richer in food but also are better for other purposes - like more suitable temperature, fewer predators, and other animals among the stalked jellyfishes that create a concurrency for food.

3 Ribbon Worms


These worms are found not only in the oceans but can also be seen in many backyards. Usually slimy, gooey worms are carnivorous and hunt their victims by venomous stings, acidic spits, toxic secretions, and even something familiar to a spidery web. Or, if they have a chance, they just eat already dead creatures to save energy for the future needs.

What makes these worms even more dangerous is that they can eat a lot bigger enemy than themselves, like snakes do. Some of their species are the longest animals on the Earth and can grow longer than a regular human, but most often stay as wide as a human finger.

How big they grow depends on their living conditions. For instance, in South America, these worms are so big that a person who would see them for the first time could think that he/she is in a nightmare. But usually, they are harmless as they don’t recognize us as their enemies.

2 Christmas Tree Worms


No, you don’t need to have them on Christmas, but if you’re interested in deep sea creatures, you should know that they are filter-feeding worms that spend their whole lives in the same place and use their highly specialized lips to catch planktons.

After thousands of years, they changed their mouths to such extent that their mouths evolved into their new eyes that allow them to see and catch enemies at the same time. This allows them to use all other parts of their body to attach themselves to rocks and coral reefs, while using their month purely for hunting.

As there are many similar animals living on rocks and corals, the best way to remember them is by recognizing their shape that is similar to Christmas trees. The primary difference is that they are much smaller and have bright-warm colors. These colors don’t give them problems, as no one eats these animals.

1 Chambered Nautilus


The nautilus is an ancient creature that has experienced no evolutionary changes in 400 million years. Because of that, they look completely the same as they were long ago. Why haven't they experienced any changes?

It's perhaps because they didn't need to evolve to thrive. Similar organisms that experienced almost no evolutionary changes are sharks, sea stars, and some turtle species.

They live in tropical waters from deep to extreme deep regions, and use their tentacles to catch smaller animals than themselves and protect themselves by using what is called “chamber” if they are attacked by bigger or stronger enemies.

However, they are rarely attacked by other creatures, as they are difficult to consume. Also, while they look quite big, they look like this because the chamber makes them seem so. Without it, they are tiny and, for a predator, would provide only little amount of calories.


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