The Mariana Trench is home to a surprising variety of life , from microscopic organisms to strange fish and gelatinous creatures specially adapted to crushing pressure, total darkness, and cold.

Where the Trench Is and What It’s Like

  • The Mariana Trench is the deepest known ocean trench, with its lowest point (Challenger Deep) reaching about 11,000 meters below sea level in the western Pacific Ocean.
  • Down there, pressure is more than 1,000 times that at the surface, temperatures hover just above freezing, and no sunlight penetrates, so life relies on sinking organic material and chemosynthesis instead of photosynthesis.

Types of Life That Live There

  • Microbes (bacteria and archaea) thrive in the sediments and water, feeding on organic detritus and chemicals like methane and hydrogen, forming the base of the food web.
  • Larger animals include crustaceans, worms, sea cucumbers, and specialized fishes that can withstand extreme pressure and low food availability.

Notable Creatures of the Mariana Trench

  • Dumbo octopus (Grimpoteuthis spp.) lives in trench depths, using ear‑like fins to “fly” through the water and eating small invertebrates in the water column.
  • The Mariana snailfish (Pseudoliparis swirei) is the deepest fish recorded, observed around 8,000 meters deep, with a soft, gelatinous body and translucent skin that help it cope with pressure.
  • A strange, unnamed jellyfish with long and short tentacles has been filmed at about 3,700 meters, likely using still, motionless ambush behavior to capture prey.

Weird Giants and Single Cells

  • Supergiant amphipods (Hirondellea gigas), shrimp‑like crustaceans, live in the trench and have exoskeletons reinforced with aluminum as well as calcium, an adaptation to extreme pressure.
  • Giant single‑celled organisms called xenophyophores (a type of monothalamea) have been found at depths over 10,000 meters; each “cell” can be the size of a mango and provides habitat for other tiny organisms.

What We Still Don’t Know

  • Only a tiny fraction of the trench has been explored; many species are known from just a few camera sightings or single samples, so scientists expect many more undiscovered organisms.
  • Ongoing deep‑sea expeditions using remotely operated and autonomous vehicles continue to reveal new species and surprising adaptations, making “what lives in the Mariana Trench” a moving target as new discoveries are reported.

TL;DR: The Mariana Trench hosts microbes, giant single cells, crustaceans, sea cucumbers, dumbo octopuses, snailfish, and mysterious jellylike creatures, all highly specialized to darkness, cold, and extreme pressure.