The deep sea is one of the least explored environments on Earth. Far below the surface, sunlight disappears, temperatures drop, food becomes scarce, and pressure becomes enormous.
Yet life thrives there.
Deep-sea animals have evolved some of the strangest bodies and behaviors found anywhere on the planet. Some produce their own light, others have enormous mouths and teeth, while some look almost completely alien.
Here are some of the strangest creatures found in the deep sea.
1. Anglerfish
The anglerfish is one of the most famous deep-sea creatures.
Many deep-sea anglerfish have a small glowing structure called an esca attached to a modified fin ray called an illicium.
The glowing lure can attract curious prey toward the anglerfish’s enormous mouth.
2. Viperfish
Viperfish look like something from a science-fiction movie.
They have extremely long, needle-like teeth and enormous mouths relative to their bodies.
Their teeth can be so long that they appear almost impossible to fit inside their mouths.
They also have bioluminescent organs that help them navigate the darkness and potentially attract prey.
3. Dragonfish
Deep-sea dragonfish have long bodies, huge mouths, and sharp teeth.
Many species possess light-producing organs along their bodies.
Some can even produce red bioluminescent light, which is unusual because much deep-sea bioluminescence is blue or blue-green.
4. Gulper Eel
The gulper eel has an enormous mouth compared with the rest of its body.
Its mouth can expand dramatically, allowing it to swallow relatively large prey.
Its tail is long and slender, making the animal look almost like a living underwater ribbon.
5. Giant Isopod
Giant isopods look like enormous versions of the small woodlice found on land.
They are crustaceans that live on the deep seafloor.
Some species can grow to several tens of centimeters long and survive in cold, high-pressure environments.
6. Dumbo Octopus
Dumbo octopuses are named after their large, ear-like fins.
They use these fins to move gently through deep water.
Unlike many shallow-water octopuses, they are adapted to life in the darkness of the deep ocean.
They often hover just above the seafloor while searching for small prey.
7. Deep-Sea Hatchetfish
Hatchetfish have extremely unusual body shapes.
Their bodies are thin and laterally compressed, resembling a small hatchet.
Many have bioluminescent organs on their undersides.
This can help them blend with the faint light coming from above in a strategy known as counterillumination.
8. Barreleye Fish
The barreleye fish has one of the strangest heads in the ocean.
Its head contains a transparent, fluid-filled dome.
Inside this dome are tubular eyes that can rotate and point upward or forward.
The unusual eyes help the fish detect prey and silhouettes against the faint light above.