The last ice age peaked about 20,000 years ago. However, many shells available commercially are taken from living animals and, as a result, the animals are left to die. Larger animals that swim on their own, such as fish and dolphins, are called nekton.
Subduction zone: Seashells left behind by dead animals can usually be taken with no harm. Experts suspect that the changes in Pfiesteria may have been caused by fertilizer and sewage runoff from hog and chicken farms in the area.
These salts also make seawater heavier than fresh water. However, they have long, poisonous tentacles they use to kill their prey. Phytoplankton are a form of algae so tiny they cannot be seen with the naked eye. Diseases such as cholera, hepatitis, and typhoid, can survive and accumulate in certain sea animals.
Continental Margin Continental shelf The continental slope Submarine canyons The continental rise Resources The continental margin is that portion of the ocean that separates the continents from the deep ocean floor. This results in an area of extreme pressure called a subduction zone.
Although the continental shelf is easier to explore than deeper areas of the ocean, there is still much to learn. The continental slopes are the most dramatic cliffs on the face of Earth. Sea snakes either come to shore to breed and lay their eggs on land or bear live young at sea, depending upon the species.
The Persian Gulf lies over a shelf that averages 164 feet below the surface. What is the width of Florida at its widest point? The continental shelf begins at the shoreline.
Seals are common along the continental shelves where they may plunge as deep as 3,300 feet 1,000 meters in search of fish. Bahrain, a tiny island in the gulf, has been the source of pearl oysters for 2,000 years.