What is the characteristics of deep sea?

* Darkness: The deep sea is extremely dark, with no sunlight reaching below 1,000 meters. This means that organisms that live in the deep sea must either rely on bioluminescence to produce their own light or find other ways to adapt to the darkness.

* Low Temperature: The water in the deep sea is cold, with the temperature below 4 degrees Celsius throughout most of the deep sea. This means that organisms that live in the deep sea must be adapted to tolerate cold temperatures.

* High Pressure: The pressure in the deep sea is enormous, with the pressure increasing by an average of 0.1 atmosphere for every 10 meters of depth. This means that organisms that live in the deep sea must be adapted to withstand high pressure.

* Low Oxygen: The oxygen concentration in the deep sea is low, with the oxygen concentration decreasing with depth. This means that organisms that live in the deep sea must be adapted to tolerate low oxygen concentrations.

* No Plants: There are no plants in the deep sea because there is no sunlight for photosynthesis. This means that all organisms that live in the deep sea must rely on dead organic matter that sinks down from the surface.

* Unique Fauna: The deep sea is home to a unique and diverse array of organisms that have adapted to the extreme conditions of the deep sea. These organisms include deep-sea fish, octopuses, squids, jellyfish, worms, and crustaceans.