Did you know that around 70% of the Earth’s surface is covered by oceans? That’s a vast expanse of water, teeming with incredible marine life! Some of the major oceans you may be familiar with include the Pacific Ocean, Atlantic Ocean, Indian Ocean, Arctic Ocean, and the Southern Ocean.
With so much water covering our planet, it’s no surprise that the oceans are home to hundreds of thousands of marine species. However, scientists believe there are still countless undiscovered creatures lurking beneath the waves. Among them are some of the most weird ocean animals you could ever imagine.
In this post, we’ll explore some of the most fascinating and unusual sea creatures. While some may be familiar, others will leave you in awe – or even a little creeped out! Many of these weird ocean animals dwell in the darkest depths of the sea, far beyond human reach, where the environment is cold, high-pressure, and mysterious.
From bizarre-looking fish to otherworldly deep-sea creatures, the ocean is full of surprises. Some of these marine animals are stunningly beautiful, while others may seem straight out of a sci-fi movie. Whether they make you laugh, gasp, or shiver, one thing is certain – you’ll be amazed by these extraordinary underwater beings!
01. Sea Pen
Sea Pens are fascinating marine invertebrates, with approximately 300 known species. They inhabit both shallow and deep waters. One particular species, the Subselliflorae, closely resembles the traditional quill pens once used for writing, which is how they got their name. Typically, Sea Pens anchor themselves to the ocean floor.
Fun fact: Although they require careful maintenance, Sea Pens are sometimes kept in larger aquariums.
02. Blobfish
The blobfish is a gelatinous deep-sea fish found along the shores of Australia, Tasmania, and New Zealand. On average, it measures no more than 30 centimeters in length, though some individuals, like the one in the image, can grow significantly larger. Its soft, jelly-like body helps it withstand the immense water pressure of its deep-sea habitat.
Fun fact: The blobfish is often labeled as the world’s ugliest animal due to its unusual appearance.
03. Pink See-Through Fantasia
The Pink See-Through Fantasia is an unusual sea cucumber distinguished by its translucent pink body. This bizarre creature resides 2,500 meters beneath the surface of the Celebes Sea. It is a relatively recent discovery.
Fun fact: This species moves through the water using small webbed feet located on the underside of its body.
04. The Squidworm
The Squidworm is a newly identified species with a somewhat eerie appearance. It can grow up to 3.7 inches in length. Despite its name, it bears little resemblance to either a worm or a squid. Instead, it has ten tentacle-like structures extending from its head.
Fun fact: The Squidworm uses these head appendages to capture particles and organic debris as food.
05. Sea Angel
The Sea Angel is a small species of sea slug that initially appears delicate and harmless. These creatures have translucent, wing-like structures on their sides, which they flap to propel themselves through the water. However, despite their angelic name, Sea Angels are actually predators that feed on other sea slugs and snails.
Fun fact: Sea Angels are tiny creatures, with the largest known species, Clione Limacina, reaching a maximum length of just 5 cm.
06. Axolotl
Axolotls, also known as Mexican salamanders or Mexican walking fish, are four-legged amphibians commonly found in lakes. They were once referred to as “water monsters.” Unlike most amphibians, adult axolotls remain aquatic throughout their lives, relying on their gills to breathe. These fascinating creatures can grow anywhere between 15 to 45 cm in length. Unfortunately, since 2010, axolotls have faced the threat of extinction due to water pollution.
Fun fact: The popular Pokémon character Mudkip is believed to have been inspired by the axolotl’s unique appearance.
07. Kiwa Crab
The Kiwa crab, scientifically named Kiwa hirsuta, is an unusual-looking crustacean that was first discovered in the South Pacific Ocean. Reaching up to 5.9 inches in length, this species is often called the “Yeti crab” or “Yeti lobster” because of the thick, hair-like structures covering its legs and pincers.
Fun fact: The setae, or “hairs,” on the Kiwa crab’s legs and pincers harbor bacteria that help purify the water surrounding hydrothermal vents, contributing to the ecosystem.
08. Pycnogonid Sea Spider
Pycnogonids, more commonly known as sea spiders, can be quite unsettling for those with arachnophobia. Despite their name and typically eight-legged structure, they are not true spiders and do not belong to the arachnid family. Some species even have 10 to 12 legs instead of eight.
Fun fact: Some pycnogonids are so tiny that they lack a respiratory system altogether!
09. Frilled Shark
The frilled shark is a rare deep-sea species found in the Atlantic and Pacific Oceans. With its elongated, eel-like body and perpetually open mouth, it has a bizarre, prehistoric appearance. These deep-sea dwellers can reach up to 6.6 feet (about 2 meters) in length.
Fun fact: The name “frilled shark” comes from its distinctive gill slits, which have extended filaments that give them a frilly appearance.
10. Longhorn Cowfish
The longhorn cowfish stands out due to its hard, angular carapace that shields most of its body. As its name suggests, it has a pair of elongated horns on its head, resembling those of a cow. These solitary creatures are highly territorial, with both males and females displaying a bright yellow hue. Additionally, they secrete toxins through their skin as a defense mechanism.
Fun fact: Like others in the boxfish family, the longhorn cowfish is an incredibly slow swimmer—so much so that it can actually be caught by hand!
11. Flying Gurnard
These fascinating, big-eyed fish inhabit the warm waters on both sides of the Atlantic Ocean. Known as the flying gurnard or helmet gurnard, they are recognized for their expansive, wing-like pectoral fins, which spread open when they become excited. These semi-transparent fins feature a striking phosphorescent blue hue along their outer edges.
Fun fact: Flying gurnards sometimes “walk” along the ocean floor in search of small invertebrates and crustaceans.
12. Mola Mola
The Mola mola, commonly called the ocean sunfish, is a massive and uniquely shaped fish. On average, they reach a length of about 5.9 feet and a height of 8.2 feet. Their bodies are laterally flattened, with prominent elongated fins extending from both the top and bottom. To sustain their enormous size, Mola molas consume vast amounts of jellyfish.
Fun fact: The largest Mola mola ever recorded measured over 10 feet in height and weighed nearly 5,000 pounds!
13. Blue Dragon
The Glaucus atlanticus, or blue dragon, is a tiny but striking species of sea slug. Fully grown, they measure around 3 centimeters in length. Their bodies feature a sleek silver stripe running down the middle, while their six appendages branch into multiple “fingers” that resemble wings when spread out.
Fun fact: Despite their small size, blue dragons can deliver a painful sting due to the venomous nematocysts they store in their bodies.
14. Carpet Shark
Also referred to as Wobbegongs, carpet sharks are a group of sharks known for the intricate patterns covering their bodies. These unique markings serve as camouflage, helping some species blend seamlessly with their surroundings.
Fun fact: Carpet sharks spend most of their time resting on the ocean floor, their patterned bodies resembling an underwater carpet.
15. Sea Pig
The sea pig, scientifically known as Scotoplanes, is an unusual deep-sea creature with a rounded, pinkish body. Growing to about six inches in length, they bear a strong resemblance to a plump potato. These strange animals are found in the Atlantic, Pacific, and Indian Oceans, feeding on organic particles scattered across the seafloor. Their stubby legs and pink coloration contribute to their pig-like appearance.
Fun fact: Sea pigs use their legs to help guide food into their mouths.
16. Red-lipped Batfish
These peculiar and somewhat eerie-looking fish are native to the waters near Cocos Island off the coast of Costa Rica. Also referred to as Galapagos batfish, they have an unusual way of moving—rather than swimming conventionally, they utilize their fins to “walk” along the ocean floor. Their diet primarily consists of smaller fish and crustaceans.
Fun fact: Similar to the Anglerfish, the Red-lipped Batfish possesses an extended structure on its head known as the illicium.
17. Mantis Shrimp
Mantis shrimp, also known as stomatopods, are vibrantly colored crustaceans commonly found in tropical and subtropical waters. Historically, they have been called “sea locusts” and “thumb splitters.” These fascinating creatures can reach up to 12 inches in length and are famous for their incredibly strong claws, which they use to strike with impressive force.
Fun fact: Some larger species of mantis shrimp have been known to shatter aquarium glass by forcefully “punching” it with their claws.
18. Narwhal
The Narwhal, sometimes spelled “Narwhale,” is a medium-sized whale species recognized for its distinctive long tusk protruding from its head. These marine mammals can grow up to 5.5 meters in length and weigh as much as 1,600 kilograms. They primarily inhabit the waters of the Canadian Arctic and the seas surrounding Greenland.
Fun fact: Narwhals communicate with one another through a variety of sounds, including clicks, whistles, and knocks.
19. Mimic Octopus
While most octopuses have the ability to change their skin color, the Mimic Octopus, or Thaumoctopus mimicus, takes it a step further. This highly adaptive species can alter both its shape and movement to imitate other sea creatures, using its flexible body as a defense mechanism. To evade predators, it often disguises itself as corals, rocks, or even other marine animals.
Fun fact: The Mimic Octopus is intelligent enough to determine which creature or object to imitate depending on the threat it faces.
20. Megamouth Shark
This deep-sea shark is one of the rarest species in existence, found in the depths of the Pacific, Atlantic, and Indian Oceans. True to its name, the Megamouth Shark swims with its enormous mouth wide open as it filters plankton and jellyfish for sustenance. It can grow up to 5.5 meters in length and weigh approximately 1,215 kilograms, with an average mouth size of around 1.3 meters.
Fun fact: The Megamouth Shark is so elusive that only 58 individuals have ever been recorded through sightings or captures.
21. Chimaera
Chimaeras are believed to be among the oldest living fish species, with origins tracing back roughly 400 million years. They typically reside at depths of around 8,500 feet in temperate ocean waters. One of the most distinctive types, the long-nosed chimaera (Rhinochimaeridae), is recognized for its elongated snout and sharp teeth.
Fun fact: A viral image of a long-nosed chimaera once circulated online, with many mistakenly identifying it as a Goblin Shark.