Deep in the ocean, there may be a yawning abyss where rare and high-quality deep-sea creatures thrive. From enormous spindly crabs to enormously adorable octopuses, discover some wonderfully strange creatures living many leagues beneath the ocean.
Adorable, Eerie, and Enigmatic Creatures
Japanese Spider Crab
The Japanese Spider Crab is a gangly deep-sea creature. Famous for having the largest leg span of any crustacean (up to 12 feet from claw to claw), this crab looks like an oversized spider. Despite its massive size, the Japanese Spider Crab is not a fierce predator. Rather, it glides on the sea floor using its long slender limbs in search of dead and decaying remains. An even more interesting fact is that young Japanese Spider Crab sometimes wear sponges or seaweed, likely to camouflage them from predators.
Flapjack Octopus
The Flapjack Octopus is undeniably cute. Its large eyes, stubby webbed hands, and ear-like fins on its mantle make this octopus adorable. The flapjack octopus is a benthic cephalopod, spending most of its time on the bottom and appearing flat, resembling a pancake from which it derives its name. When it is time to fly, the flapjack octopus swims or hovers above the bottom by flapping its fins and pulsing the membrane along its fingers, giving it an appearance resembling a jelly-like pulsating creature rather than a true octopus. Unlike many shallow-water octopus(creatures) species, the flapjack octopus lacks an ink sac and cannot change color for camouflage.
Sea Pig
The sea pig may also get its name from its crimson-colored body and love of the muddy seafloor, but it is a species of sea cucumber. This peculiar-looking, but extremely cute, creature has tubular fingers on its belly, back, and around its mouth. The sea pig spends its days sniffing around in the muddy sediments of the seafloor, eating bits of dead algae and animals that have fallen from the ground. When something large, such as a whale, sinks to the seafloor, large herds of sea pigs move in to feast on the rich organic sediments of the decaying carcass.
Sea pigs are likely babysitters of the deep sea. Our fellow students at the Monterey Bay Aquarium Research Institute (MBARI) frequently see juvenile lithodid crabs (Neolithodes diomedeae) climbing or hiding beneath sea pigs, likely as a way for the young crabs to protect themselves from predators(creatures).
Large Isopods
These plump deep-sea creatures resemble their distant relatives, the tiny tablet insects found in many gardens. One difference between the giant isopod and your run-of-the-mill Trojan horse is their size: large isopods can grow up to 40 centimeters long! This oversized crustacean slowly wanders along the seafloor, feeding on dead animals. It is found in deep, cold waters and can withstand depths of more than 7,000 feet (2,100 meters).
Sea Angel
Sea angels are tiny, swimming sea slugs whose visible bodies and flapping wings make them look more heavenly than slugs. That cold-water, deep-sea population are modified gastropods: the muscular foot common in gastropods (snails and slugs) has evolved into wing-like appendages for powerful swimming in open water, and their shells have been lost.
Don’t let their angelic appearance fool you: Sea angels use their radula and tentacles to pull different swimming snails out of their shells and eat them. They feed exclusively on Clione limacina, a species of shelled pteropod that is predicted to be negatively impacted by climate change and ocean acidification.
Large larvae
Regardless of its call, a large larva is less than 10 centimeters (four inches) long. But this tiny, loose-swimming invertebrate is a remarkable snot architect. Large larvae create an elaborate shape from slimy mucus that can be up to 3 feet wide—their snot palace. The larvae use the shape to trap food within marine snow drifting in from the waters above. If the snot filter becomes clogged, the large larvae can quickly get rid of it and build a new one. The abandoned snot house sinks to the seafloor, where it provides vital food and nutrients to other animals in the deep sea. Watch as we dive inside the snot palaces of large larvae with MBARI scientist Kakani Katija.
Blood-belly Comb Jellyfish
The song of the blood-belly comb jellyfish may be macabre, but the animal itself is stunningly beautiful. The heart-shaped, bright red blood-belly comb jellyfish is protected by tiny cilia that beat constantly, propelling it through the water. When light hits the cilia, it is refracted, creating a brilliant spectacle. Ironically, at the depths where this jellyfish lives, its pink coloration makes it nearly invisible to predators. Pink light disappears in this jellyfish’s dark, deep-water habitat, and biologists agree that its colorful pink belly helps disguise bioluminescent prey, which, if kept bright, can also make the jellyfish a meal.
Anglerfish
With their predating behavior, these fishes have rightfully acquired the angel name. Characterized by a fierce appearance, anglerfishes possess an elongated structure, originating from their snout, with an organ at the extremity containing millions of bioluminescent bacteria. This fishing rod throws a bright point of light just above the anglerfish’s mouth perfect trap to lure inquisitive prey. The anglerfish simply sits and waits for an unsuspecting fish to swim by. There is little prey in the deep sea, so this method of fishing can help the anglerfish save energy while it tries to find its next bite.
Want to know another mind-blowing truth about these toothy fish? In some species, a tiny, parasitic male will latch onto the much larger female with his teeth until she absorbs him completely—her skin and blood vessels fuse and many of her organs fall apart. The male begins to evolve to get all the nutrients he needs from her blood. Soon, the female can use (what little is left of) her mate to reproduce and spawn.
Large Siphonophore
The large siphonophore looks more like a silly string than an animal: its elongated, rope-like shape floating in the depths of the ocean can stretch to reach 40 m in length. The large siphonophore, like many other siphonophores, is a set of relatively specialized functional parts: some capture prey, some digest food, some reproduce, and others direct the action by swimming. This siphonophore is bioluminescent: it creates its light. When it collides with something, its stem glows with an intense blue light.