8 deep sea creatures that survive without sunlight: Giant tube worms, hadal amphipods

Life in the abyss: Creatures that never see the sun

Sunlight drives almost all life on Earth. But in the deep ocean, kilometres below the surface, darkness is permanent. Here, organisms have evolved to survive without any light at all.

Scientists have catalogued at least eight distinct creatures that thrive in these extreme conditions. Among the most famous are giant tube worms, which cluster around hydrothermal vents on the ocean floor.

Giant tube worms: Chemosynthesis over photosynthesis

Giant tube worms, or Riftia pachyptila, can grow over two metres long. They live near volcanic vents that spew superheated, mineral-rich water. Instead of eating, they host symbiotic bacteria inside their bodies. These bacteria convert hydrogen sulfide from the vent fluid into organic matter, a process called chemosynthesis.

Without a mouth or digestive system, the worms rely entirely on this bacterial partner. They have bright red plumes that absorb oxygen and hydrogen sulfide from the water. These creatures were first discovered in 1977 near the Galapagos Rift.

Hadal amphipods: Scavengers of the deep trenches

Hadal amphipods are small, shrimp-like crustaceans found in the deepest parts of the ocean, such as the Mariana Trench. They live at depths exceeding 10,000 metres. Recent expeditions have found them thriving in the hadal zone, where pressure is over 1,000 times atmospheric pressure at sea level.

These amphipods are scavengers, feeding on dead organic matter that sinks from above. They have adapted to the crushing pressure by using special enzymes and flexible body structures. Some species can even digest wood and plant material that falls into the trench.

Other deep-sea survivors

Other creatures on the list include the yeti crab, which farms bacteria on its hairy claws near hydrothermal vents. The dumbo octopus, named for its ear-like fins, drifts at depths of up to 7,000 metres. The frilled shark, a living fossil, hunts in the twilight zone between 200 and 1,500 metres.

Deep-sea jellyfish, such as the Atolla jellyfish, produce bioluminescent flashes to startle predators. Giant isopods, resembling oversized pill bugs, scavenge the seafloor at depths of 500 to 2,000 metres. Finally, the anglerfish uses a bioluminescent lure to attract prey in the pitch-black waters.

Deepest ecosystem ever recorded

In July 2026, The Times of India reported that scientists discovered the deepest animal ecosystem ever found, thriving nearly 10 kilometres beneath the Pacific Ocean. The ecosystem was found in a deep trench, with organisms living in complete darkness and under extreme pressure.

Researchers described the discovery as 'enormous and alive'. The exact species found have not been fully identified yet, but they are believed to include new types of amphipods, polychaete worms, and other invertebrates adapted to the hadal zone.

Officials have not yet confirmed the full extent of the ecosystem. Further expeditions are planned to study how these creatures survive without sunlight and what they can teach us about life in extreme environments on Earth and beyond.

What to watch: Scientists are now investigating whether similar ecosystems exist in other deep ocean trenches worldwide.