Direct answer
The deep sea contains fishes, squid, octopuses, jellies, comb jellies, crustaceans, worms, sea cucumbers, corals, sponges, microbes, and many other groups. Different communities occupy open water, seafloor plains, trenches, vents, seeps, and animal falls.
The deep sea is many habitats, not one empty place
Open water below 200 meters covers an enormous volume, while the seafloor includes continental slopes, canyons, abyssal plains, seamounts and trenches.
Hydrothermal vents, cold seeps and whale falls create concentrated islands of food and chemical energy within the broader food-poor deep ocean.
Twilight-zone animals
Lanternfishes, bristlemouths, dragonfishes, squid, krill, siphonophores, jellies and zooplankton are common members of the mesopelagic community.
Many rise toward the surface at night and return to depth before daylight.
Midnight and abyssal animals
Anglerfishes, rattails, deep-sea squid, octopuses, sea cucumbers, amphipods, sponges, corals and gelatinous animals occupy the dark water column and seafloor.
Many depend on marine snow, scavenging, predation or chemosynthetic food webs.
Hadal trench animals
Trench communities include amphipods, sea cucumbers, worms, microbes and specialized snailfishes in the shallower portion of the hadal zone.
Fish appear to have a physiological depth limit near 8,400 meters, while invertebrates and microbes continue deeper.
At a glance
| Habitat | Representative life | Primary food pathway |
|---|---|---|
| Twilight water column | Lanternfish, squid, jellies | Surface production and migration |
| Midnight water column | Anglerfish, dragonfish, siphonophores | Predation and sinking particles |
| Abyssal seafloor | Sea cucumbers, worms, sponges | Marine snow and carcasses |
| Vents and seeps | Tubeworms, mussels, microbes | Chemosynthesis |
| Hadal trenches | Amphipods, snailfish, microbes | Accumulated organic matter and local chemistry |
Frequently asked questions
Do sharks live in the deep sea?
Yes. Several shark species use deep water, although sharks are not present at the greatest trench depths.
Are there plants in the deep sea?
Photosynthetic plants cannot grow where sunlight is absent. Deep ecosystems rely on food sinking from above or on chemosynthesis.
What is the most common deep-sea fish?
Bristlemouths are often described as extraordinarily abundant and may be the most numerous vertebrates on Earth.
How many deep-sea species are undiscovered?
No reliable exact count exists. New species and previously unseen behaviors continue to be documented.
Evidence
Sources reviewed
- Animals of the DeepMonterey Bay Aquarium Research Institute · checked 2026-07-30
- The Deep SeaSmithsonian Ocean · checked 2026-07-30
- Twilight zoneWoods Hole Oceanographic Institution · checked 2026-07-30
- Midnight zoneWoods Hole Oceanographic Institution · checked 2026-07-30
- Hadal zoneWoods Hole Oceanographic Institution · checked 2026-07-30
- What is the deepest-living fish?NOAA Ocean Exploration · checked 2026-07-30