Most people now the ocean only in an intertidal zone, were the water meets the land, and the epipelagic zone, the upper sunlight zone of the open ocean. Though these zones contain the abundance of the ocean life, because sunlight makes photosynthesis available (sea plants), but these places do not contain even a tenth of the life “down under”.

Photosynthesis occurs only down to about 100-200 m, and sunlight disappears at 1000 m. Altogether the ocean is 11.000 m deep in the Mariana Trench!

To get an idea of how vast the ocean’s depths are, consider it 79% of the earth’s biosphere!

Thanks to image capturing and sampling technologies, marine biologists can explore the deepest points of the ocean. Deep sea research is vital because it is such a big part of the biosphere. Despite its depth and distance, it is still our backyard in comparison to outer space. And yet we have more information about the surface of Mars and the Moon, than the deep sea!

The oceans are divided in two road realms: the pelagic and the benthic.

Pelagic refers to the open water in which swimming and floating organisms live. Organisms living there are called pelagos, like the reef fish (Yellow Tang, Damselfish, Sea Horses etc.), or the demersal fish (Bluespotted Ribbontail Ray, Flounder, The Great Hammerhead Shark etc.).

Depth and layers of the Ocean:

– Epipelagic (sunlit) Photic zone: From the surface, down to about 200 m. This is the part of the sea, were there is enough light for photosynthesis.

– Mesopelagic (twilight) Mezopelagic zone: The name comes from the Greek méson (middle) From 200 m to about 1.000 m. Examples of animals who live here: Swordfish, Squid, Wolffish, and some species of Cuttlefish.

– Bathypelagic (midnight) Bathyal zone: The name comes from the Greek bathys (deep) From 1.000 m to 4.000 m. The name stem is from the Greek bathys (deep). At this depth the ocean is pitch black, there are no living plants. Most animal living here survives by consuming detritus (non living particulate organic material, like decomposers, fungi and bacteria, sometimes even dead skin) falling from the zones above, which is known as “marine snow”.

Fish like the Marine Hatchetfish live here.

– Abyssopelagic (lower midnight) Abyssal zone: From 4000 m to above the ocean floor. The name comes from the greek ábyssos (bottomless). Very few creatures survive in such cold temperature, very high pressure, and complete darkness. Animal like the Basket Star, the Sea Spider and the Sea Pig live here.

BASKET STAR

SEA SPIDER

– Hadopelagic Hadal zone: The name comes from the Greek Haides (Hades), the classical Greek underworld. Very few creatures are known here.

The ocean looks something like this:

So, I hope this helped you know the oceans better, next time, I will write posts about animals living in the Deep Dark.

So long!