Humans have been exploring the ocean floor for hundreds of years, yet much of the underwater world remains a mystery. The deeper you travel, the colder, darker, and stranger it becomes. Sunlight disappears, pressure increases, and food becomes incredibly difficult to find.
These harsh conditions made the animals living there come up with some unusual survival tricks. They might look terrifying to us, but every strange feature has a purpose.
1. Giant Spider Crab (Macrocheira kaempferi)
Found in the waters around Japan, these massive spider crabs are the largest living crab species by leg span. Its long, spindly limbs can stretch approximately 12 feet from tip to tip, making it look like an enormous underwater spider.
Despite their intimidating appearance, spider crabs are mainly scavengers feasting on whatever morsels of food they can find, including dead animal bits, shellfish, and other easy meals.
These crabs can usually be found hundreds of feet below, so you will never see one tickling your feet in the beach area.
2. Barreleye Fish (Macropinna microstoma)
The barreleye fish looks like someone designed it for a low-budget science-fiction movie and forgot to spray-paint the Plexiglas parts. Its most famous feature is, of course, its transparent head, through which you can clearly see its large peepers.
Those eyes are usually pointed upward to look for silhouettes of prey, but the fish can turn them forward when it is time to eat. Scientists believe the transparent shield may also protect the barreleye's sensitive eyes when it steals food from siphonophores, strange colonial animals equipped with stinging tentacles.
3. Vampire Squid (Vampyroteuthis infernalis)
With a name like "vampire squid from hell," this little guy sounds much more dangerous than it actually is. It doesn't drink blood, and it's not even technically a true squid or an octopus.
It lives in deep waters where oxygen levels can be extremely low and survives mainly on "marine snow," a steady shower of tiny organic particles sinking from above.
Webbing between its tentacles resembles a dark cloak, which explains the vampire comparison. If threatened, it can release a cloud of glowing mucus that distracts predators while it slips away.
4. Blob Sculpin (Psychrolutes phrictus)
The blob sculpin is often confused with the famous blobfish, but they are not quite the same creature. Blob sculpins live thousands of feet beneath the northern Pacific, where crushing pressure and near-freezing temperatures would kill most animals in seconds.
Their soft, tadpole-shaped bodies are perfectly suited to life on the seafloor. Because they don't need to race after prey, they can wait for food to come within reach.
5. Frilled Shark (Chlamydoselachus anguineus)
The frilled shark looks nothing like its cousins and more like a sea serpent from an old sailor's story. It has a long, eel-like body, a broad head, and six pairs of frilly gill slits that provide the species its name.
It usually lives deep in the Atlantic and Pacific oceans, where it hunts fish, squid, and other marine animals using its backward-pointing teeth that help it hold onto slippery prey.
6. Oarfish (Regalecus glesne)
Meet the world's longest bony fish. Oarfish live in deep waters around the world and are rarely observed alive. When resting or feeding, they sometimes float vertically in the water, with their heads pointing upward.
Its silvery body, red fins, and ribbon-like shape probably inspired many historical reports of gigantic sea serpents, but it prefers to feed on small creatures and plankton rather than attack ships or drag sailors overboard.
7. Anglerfish (Diceratias pileatus)
There aren't many deep-sea creatures that live in people's nightmares that are as creepy as the anglerfish. Its body basically consists of a huge head with an enormous mouth filled with dozens of needle-like teeth.
Thanks to sexual dimorphism, female anglerfish have that little dangling bit that hangs above their mouth like a fishing rod.
Its glowing tip contains bioluminescent bacteria and acts as a lure. Curious prey swim toward the light, only to discover that not all that glitters is food.
8. Cookiecutter Shark (Isistius brasiliensis)
The cookiecutter shark is on the smaller side of the family, but it has one of the strangest feeding methods in the ocean. It attaches itself to larger animals and uses its unique mouth to remove a neat, circular piece of tissue, leaving behind a mark that looks as if it was made with a cookie cutter.
Cookiecutter sharks have been recorded to take bites from tuna, whales, dolphins, and even underwater equipment. They probably didn't like that last one, but when you're hungry, even steel and rubber must look delicious.
9. Dinner Plate Jellyfish (Solmissus incisa)
Found thousands of feet underwater, the dinner plate jellyfish actively hunts zooplankton and may even prey on other jellyfish, instead of just drifting in the water like a plastic bag.
Scientists have photographed these animals around deep underwater mountains, including the Musicians Seamounts near Hawaii. Expeditions to such poorly studied locations continue to reveal unfamiliar species that will eventually haunt our dreams.