Over 70% of our planet The world is covered by water, making it a vast and virtually unexplored territory. The oceans hide a multitude of mysteries, and one of the most intriguing are the animals that live in their depths. Forced to adapt to extreme conditions such as lack of light, extremely low temperatures and pressure, these animals have developed unusual characteristics that surprise us.
In this article you will discover some of the rarest animals in the sea and its fascinating features.
frilled shark
One of the most fascinating and ancient sharks is the frilled shark (Chlamydoselachus anguineus), also known as the frilled shark for its long, flexible, snake-like body structure. This shark is considered a living fossil, as it retains many of the characteristics present in prehistoric sharks that inhabited the oceans millions of years ago.
It can reach up to 4 meters in length and has a dark brown color. It has dorsal, pelvic and anal fins, which makes it an agile swimmer in the dark ocean depths. Unlike other sharks, this one adapts perfectly to life at depths that can reach 1500 meters.
The frilled shark feeds mainly on cephalopods and other fish. Its jaw has rows of small, sharp teeth, which allow it to catch slippery prey. One amazing aspect is that its hunting is reminiscent of how snakes act: it bends its body and launches itself towards its prey quickly and precisely.
It lives in the Atlantic and Pacific oceans in different habitats, moving through different depths. Although it usually escapes the sight of humans, this strange fish is occasionally sighted in shallower waters, making it a real surprise for marine researchers.
Psychrolutes micropores (Blobfish)
This strange fish, commonly known as blob fish, has become one of the most iconic marine animals due to its peculiar gelatinous appearance. Its flesh has a density slightly lower than that of water, allowing it to float at depths of up to 1000 meters without expending energy on swimming. This characteristic is key to its survival in the depths of the ocean, where the pressure is much greater than on the surface.
The Blobfish (Psychrolutes micropores) lives mainly in the deep waters around Australia and New Zealand. However, its lifestyle makes it a very difficult animal to observe. What is most surprising is that its appearance changes dramatically when it is taken out of the water due to the difference in pressure: what has an adapted and efficient shape under water, on the surface it turns into a mass of soft and unstructured flesh.
arothron meleagris
El arothron meleagris This is a puffer fish that stands out not only for its size, which can reach up to 65 centimetres in length, but also for its peculiar defence mechanism. When it feels threatened, this fish is capable of inflating itself by swallowing water up to three times its normal size, making it difficult for predators to catch and devour it. In addition, it has a skin covered in spines and toxins that make it even more difficult to consume.
Its distribution is varied, and it can be seen from East Africa to Easter Island, especially in tropical areas rich in coral reefs. It lives among corals and algae, and feeds mainly on mollusks, crustaceans and other marine invertebrates, with the help of its strong teeth.
Yeti Crab
El Yeti crab (hirsute kiwa) is a crustacean discovered in 2005 in the depths of the Pacific Ocean near Easter Island. What most attracts attention about this animal are the silky filaments that cover its claws, giving it a hairy and somewhat intimidating appearance. Although it may seem like a simple decoration, these "hairs" are covered with bacteria that help it detoxify the sulfurous gases from the hydrothermal vents where it lives.
Its natural habitat is at depths of up to 2300 metres in the cold waters of the Pacific. Research suggests that the Yeti crab cultivates these bacteria to use as food, making it an even more fascinating creature. Furthermore, its lack of vision – due to the absolute darkness in which it inhabits – means that it relies entirely on its other senses and its symbiotic bacteria to survive.
Sea Dragon
El sea dragon leafy (Phycodurus eques) is one of the most elegant creatures in the ocean, both for its appearance and for its exotic way of moving. Related to seahorses, the sea dragon uses leaf-like extensions of its skin to camouflage itself among seaweed and escape from predators, making it almost invisible in its surroundings. This animal, which can reach up to 50 cm in length, is endemic to the coastal waters of southern and eastern Australia, having been declared endangered due to overfishing and the degradation of its natural habitat.
Unlike other related fish, the sea dragon deposits its eggs on the male's body, where they are incubated until they are ready to hatch. This fascinating reproductive strategy is shared with seahorses and ensures the survival of the offspring in a predatory environment.
Dumbo octopus
El Dumbo octopus, scientifically known as grimpoteuthis, is one of the friendliest inhabitants of the deep sea. Its name comes from the fins on its head that resemble the ears of Walt Disney's famous elephant, Dumbo. This octopus uses these fins to move gracefully through deep waters, reaching depths of between 3000 and 5000 meters.
This small octopus (usually no more than 20 cm long) is completely benthic, meaning it spends most of its life at the bottom of the ocean. It lives in extreme conditions of pressure and cold, near hydrothermal vents and underwater canyons. It feeds mainly on marine invertebrates, such as small crustaceans and worms.
Ax fish
El ax fish (Argyropelecus gigas) is one of the most intriguing animals on the seabed. This fish lives at depths of over 600 metres and has developed the ability to become practically invisible in order to survive. Its ability to blend in with its surroundings and reproduce the reflections of light coming from the surface makes it difficult to detect by both its prey and predators.
The hatchetfish is one of the main predators in its environment, using its fluorescent organ to stalk its prey. The size of this fish is relatively small, reaching only about 15 centimeters in length, but its ability to adapt to the depths makes it a true miniature predator.
Frog fish
El frog fish is a master of camouflage on the seabed. This animal, scientifically known as Halobatrachus didactylus, has the appearance of a rock covered in algae, which allows it to go unnoticed while stalking its prey. One of its most curious characteristics is that, despite being a fish, it prefers to "walk" on the ocean floor using its modified pectoral fins, rather than swimming.
The toadfish primarily inhabits warm, shallow waters, such as those around Africa and Indonesia. Its body is covered in tiny, hair-like protrusions, further enhancing its camouflage ability. When ready to strike, the toadfish quickly pounces on its prey, using its powerful jaw to capture it in a fraction of a second.
sea pig
El sea pig (Scotoplanes globosa) is an echinoderm that lives on the ocean floor, mainly in the cold waters of the Atlantic and Pacific at depths that can exceed 1000 meters. This inflated-looking animal, which looks like a pink pig, has developed adaptations to live in the abyssal darkness, where it feeds on decaying organic matter and microorganisms found in marine sediment.
Unlike many deep-sea animals, the sea pig does not rely on hunting. Instead, it acts as a “cleaner” of the seabed, making it an essential component of the ecosystem. The average size of a sea pig is about 15 cm, although some specimens can be larger.
hagfish
The hagfishHagfish, or hagfish, are one of the oldest and strangest species in the marine world. These creatures lack jaws and their mouths contain two structures that move horizontally to catch their prey. A curious fact about these animals is that they feed on the entrails of dead or dying animals, and sometimes, they even enter the body of their live prey to devour it from the inside.
In addition, these fish produce a huge amount of protective mucus when they feel threatened, making them slippery and difficult for predators to catch. The mucus not only acts as a physical shield, but can also suffocate other fish in their immediate surroundings, increasing their chances of survival. They mostly live in deep waters, where sunlight barely penetrates.
These fascinating animals are a reminder of how little we still know about our planet's oceans. Every year, scientists discover new species that inhabit the depths and that have surprising characteristics, many of which, to us, still seem straight out of a science fiction book.