What is the ocean?

Extent of the marine environment.

1. Oceans cover 71% of the earth’s surface, or 143,000,000 square miles.
2. The average depth of the oceans is 4000 meters. The deepest point is the
Marianas Trench, 10,000 meters, or 38,000 feet, or 7 1/2 miles deep.
3. The oceans contain a lot of water: 1.4 billion cubic kilometers of water, or
3.62 x 10²⁰ gallons of water.
4. When depth and volume are considered, the marine biosphere is more than 300
times the extent of the terrestrial and fresh water realms.
5. Yet, as far as is known, there are much fewer species of organisms in the oceans
as compared to land, although every phylum (major group) is represented in
the oceans. undoubtedly, the total number of species is profoundly influenced
by the proliferation in the terrestrial environment of two major groups of
organisms: the flowering/rooted plants and the insects.

What is the ocean?

a. Made up of water that has a bunch of dissolved salts in it.
b. Covers a lot of surface area
1). Pacific Ocean, largest, covers 64 million square miles
2). Atlantic Ocean, second largest, covers 32 million square miles.
3). Indian Ocean, nearly as large as the Atlantic, covers 28 million square miles
4). Arctic Ocean, is the smallest and shalllowest ocean, covering 4.7 million
square miles
5). Antarctic ocean, which can be considered extensions of the Indian, Pacific,
and Atlantic oceans, surrounding Antarctica, covers 13.5 million square
miles
6). Caribbean Sea covers 1.7 million square miles
7). Mediterranean Sea covers 1.2 million square miles
8). North Sea is tiny, covering only 220,000 square miles
9). Red Sea, separating northern Africa from Saudi Arabia, covers 170,000
square miles
10). Persian Gulf, separating Saudi Arabia from Iran, covers 90,000 sq mi

c. Deep, with lots of relief over parts of the bottom
1). Avg. depth is 12,470 feet, or 3.8 kilometers, or 2.3 miles
2). 8% of the oceans (6% of the earth's surface) covers shallow waters
(less than 200 meters deep) which provides the bulk of oil, fishing, and
mineral mining and where pollution is a major concern
3). The remainder of the oceans is deeper than 200 meters, with the deepest
parts of the ocean being found in the Pacific: the Marianas Trench is 36,163 feet deep at the deepest part (11,022 meters or nearly 7 miles); Mauna Kea, on the island of Hawaii, rises 33,450 feet from the surrounding ocean floor (10,200 meters) as compared to Mount Everest, which reaches 29,020 feet (8,848 meters) above sea level, being the highest point on land and the Grand Canyon, one of the deepest canyons on land, is 5,300 feet deep (1,615 meters).
4). If all the land on earth were leveled, sea water would cover the earth to a
depth of 1.6 miles or 2.7 kilometers.
5). Just goes to show how much water is contained in the oceans: another way
of viewing this is that there is more than 60 billion gallons of sea water for every person on earth.

d. Provides a habitat for plants and animals that live in that broad expanse
1). 98% in volume of the biosphere in the oceans (land volume is only a few
meters below the surface and not much above the tree canopies) available for habitation
2). Most of the organisms (all of the plants) live within the shallow waters
above 200 meters, but most of the volume is much deeper than that

Classification into zones.

1. In order to facilitate the study of organisms and their distributions, many attempts have been made to divide up the oceans into zones.

2. There are 2 primary divisions: the benthic zone (all of the ocean floor) and the pelagic zone (whole mass of water).

3. The boundaries of some of these zones are well-defined in some instances, but most often, there is a great deal of overlap. The various classification systems have attempted to draw boundaries where there is the most distinctive biotic changes and often, these zones have been named for the dominant species found in the zone.

4. Pelagic = open sea, or oceanic, usually in waters where the depths are greater than 200 meters; near-shore or neritic, where the depths are shallower than 200 meters.

5. benthos = organisms living in association with the bottom:
a. epiflora or epifauna = those plants (flora) or animals (fauna) which live at the surface of the substrate or bottom such as benthic diatoms, coralline red algae, sponges, lobsters, abalone.

b. infauna = animals which live in the bottom, such as clams, garden eels, sand crabs, worms. There are no plants which live in the bottom; plants need light.

6. Plankton= floating, with poor swimming ability; nekton = good swimming ability.

7. Although the classification into zones that are based on temperatures are easily defined in the terrestrial environment, generally following latitudinal lines, the existence of the expansive oceanic currents in the major oceans “tilt” the temperature zones so that the warmer waters extend northward in the western parts of the North Pacific and North Atlantic and southward in the western parts of the South Pacific, South Atlantic, and Indian oceans. At the same time, the cooler waters extend southward in the eastern parts of the North Pacific and North Atlantic and northward in the eastern parts of the South Pacific, South Atlantic, and Indian oceans. The distribution of biota corresponds to these shifts, as per the tropical elements seen off the coasts of Florida and southern Japan versus the cold temperate species off western Europe and North America.

8. Zoogeographers and phytogeographers were not able to correlate the distributions of many oceanic species accurately with a strict description of temperature alone; thus, they turned to other parameters in attempting to circumscribe entities of water in the open oceans in describing the distributions of marine plants and/or animals.

a. The most successful to date has been the use of “water masses” which are defined on the basis of temperature and salinity versus depth profiles. Thus, t-s curves taken at different stations and different depths within the same “area” all fall within an envelope of curves; hence, an Equatorial water mass, a North Central water mass, a Sub-arctic water mass.

b. Another useful parameter has been the dissolved oxygen content of the water. in areas of low oxygen concentrations, fish species have increased the gill filament surface areas to more efficiently uptake the little oxygen that is present whereas in areas of high oxygen concentrations, related species have decreased the gill filament surface areas and have “fused” the gill filaments into a membrane, probably for more effective food-gathering.