Open Sea Neighborhoods
Sympagic
A sympagic environment is one where water exists mostly as a solid, ice, such as a polar ice cap or glacier. Solid sea ice is permeated with channels filled with salty brine. These briny channels and the sea ice itself have its ecology, referred to as "sympagic ecology"
Pelagic
The word "pelagic" is derived from Ancient Greek πέλαγος (pélagos) 'open sea'. The pelagic zone can be thought of in terms of an imaginary cylinder or water column that goes from the surface of the sea almost to the bottom. Conditions in the water column change with distance from the surface (depth): the pressure increases; the temperature and amount of light decreases; the salinity and amount of dissolved oxygen, as well as micronutrients such as iron, magnesium and calcium, all change. The pelagic zone refers to open and free waters in the body of the ocean that stretch between the ocean surface and the ocean bottom and are not too close to some boundary, like a shore or the seafloor or the surface. Marine life living in the pelagic zone can swim freely in any direction, unhindered by topographical constraints.
The Pelagic is divided into 5 layers:
Epipelagic – sunlight zone – 660 ft deep. Nearly all primary production in the ocean occurs here
Mesopelagic – twilight zone – 660 to 3300 ft. Many organisms that live in this zone are bioluminescent.
Bathypelagic – midnight zone – 3300 to 13000 ft. Pitch black. No plants. Occasional bioluminescent organisms. This is where sperm whale hunt giant squid.
Abyssopelagic – abyssal zone – 13000 to ocean floor. Many species at this depth are transparent and eyeless.
Hadopelagic/Hadalpelagic – hadal zone – any depth past 20,000 ft. This is usually a deep trench.