|Themes > Science > Earth Sciences > Oceanography > Ocean Regions > Blue Water > Characteristics|
By simply looking at the surface, sitting in a boat or standing on the shore, it's very difficult to see the amazing diversity of life that exists in the ocean.
The ocean is vast, covering a little more than 71 percent of Earth's surface. Of that, 65 percent is considered blue water (open ocean)--waters that lie beyond the coastal shallows (coastal ocean). The world of people, trees and birds is relatively flat, never extending too far above or below the ground. Oceans are different; they have an average depth of more than 2 miles and contain life nearly everywhere, even on the deepest bottoms!
Oceanic life is divided into two major categories: the benthic environment (the sea floor) and the pelagic environment (the ocean waters). The pelagic environment is further divided based on water depth.
The neritic zone is the
first 200 meters (656 feet) of ocean water, which includes the seashore
and most of the continental shelf. Most photosynthetic life (life that
uses light enery to convert carbon dioxide and water into food), such as
phytoplankton and floating sargassum, is found in this region. Zooplankton,
which is the floating creatures ranging from microscopic diatoms to small
fish and shrimp, also live here. Many species of whales, like the gigantic
blue and humpback whales, feed almost entirely on the tiny zooplankton.
These whales force seawater through baleen plates (combs of bony material
that form in the place of teeth) to filter out the tiny sea creatures. The
largest of all ocean dwellers, the whale shark, lives off plankton alone!
The oceanic zone extends
from 200 meters (656 feet) deep all the way down to the bottom of the
ocean, which can be thousands of meters deep.