pelago-, pelag- +

1. A reference to the region of deep water which excludes the ocean floor; floating in the ocean depths. Living in the oceanic water column at depths of between 4,000 and 6,000 meters [13,120 feet to 19,680 feet], seaward of the shelf-slope break: "The marine biologists used specialized mechanical diving equipment to explore the abyssopelagic depths of the sea."
2. Of or relating to organisms or phenomena in mid-water, but still at great depths: "At the abyssopelagic depths of the sea, many of the creatures are blind."

A reference to organisms occurring, or living, at various ocean depths or in the pelagic zones; in response to influences other than temperature.

Indo-Australian Archipelago: The combined region formed by the Malay Peninsula, northern Australia, and the numerous islands of Indonesia, the Philippines, and Melanesia.

1. The Aegean Sea, between Greece and Asia Minor.
2. Any sea, or sheet of water, in which there are numerous islands; a group of islands.
3. A large group of islands; such as, the Philippine archipelago.
4. A sea, such as the Aegean, containing a large number of scattered islands.

Epipelagic (the stratum of the oceanic zone where enough light is present for photosynthesis to occur); used in reference to planktonic organisms living continually at the sea surface.

1. The biogeographic realm of the ocean, or living in the depths of the ocean; especially, between about 1000 and 4000 meters (3,280 and 13,120 feet).
2. A reference to creatures living in the bathyal region of an ocean.
3. Found in the depths of the sea.

A layer of the oceanic zone lying below the mesopelagic zone and above the abyssopelagic zone, at depths generally between about 1000 and 4000 meters (3,280 to 13,120 feet).

The bathypelagic zone receives no sunlight and water pressure is considerable. The abundance and diversity of marine life decreases with depth through this and the lower zones.

Spanning the deepest to the highest levels, or areas, of oceans, seas, lakes, etc.

1. A reference to, belonging to, or being marine organisms living at great depths throughout most of the year; however, during the winter they move to the surface.
2. Pertaining to certain deep-sea organisms which inhabit surface-water only during the winter.
3. Referring to or designating certain bathypelagic (biogeographic region of the the ocean bottom) organisms that appear at the surface of the ocean only in the winter.

1. Relating to or living in the upper zone of the ocean, from the surface to a depth of about 200 meters (656 feet).
2. Of or relating to the part of the oceanic zone, or stratum. into which enough sunlight enters for photosynthesis to take place.

Organisms in open ocean water away from the sea bed.

The bottom-most layer of the oceanic zone, lying below the abyssopelagic zone at depths greater than about 6000 meters (19,680 feet).

A reference to the deep water in ocean trenches. The name is derived from Hades, the classical Greek underworld. This zone is 90% unknown and very few species are known to live here (in the open areas); however, many organisms live in hydrothermal vents in this and other zones.

Salty sea.

Organisms that remain pelagic throughout life.

1. A reference to organisms that are only temporary members of the pelagic community.
2. The pelagic larval stages of certain benthic marine organisms that are only temporary members of the plankton community.