Thursday, April 18, 2013

Discover an Underwater Ecosystem

By Natalie Ashers


Oceans cover more than two thirds of the earth's surface, and they are very deep! Fish and other animals make their homes in all different parts of the ocean, even on the bottom, or sea floor. The ocean is also filled with lots of plants, which provide food, homes, and protection for ocean animals. A person who studies ocean life is called a marine biologist.

In 1960, a descent was made to 10,916 m/35,813 ft in the Challenger Deep external of the Marianna trench-the deepest known point in the oceans, 10,924 m/35,838 ft deep at its maximum, near 11 22'N 142 36'E-about 200 miles southwest of Guam. The dive was made in the bathyscape Trieste external built by Auguste Piccard, his son Swiss explorer Jean Ernest-Jean Piccard and U.S. Navy Lieutenant Don Walsh. The descent took almost five hours and the two men spent barely twenty minutes on the ocean floor before undertaking the 3 hour 15 minute ascent.

Some creatures that live in the ocean use a special chemical reaction inside their bodies to create a glowing light. The light is called bioluminescence and happens when certain chemicals mix together, along with some oxygen from the water, in a particular part of the animal's body.

Sharks have several rows of sharp pointed teeth and powerful jaws to tear off big pieces of food, which they swallow whole. They don't even need to chew their food! Sometimes sharks lose teeth, but when they do, new ones grow in their place. Sharks have several rows of teeth. They eat bony fish, squid, marine mammals, and even sea turtles. They have an excellent sense of smell, which helps them find food. Many sharks eat near the surface of the water, but will also dive down deeper in search of food.

Marine mammals need to come to the water surface to breathe, which is why the deep-diving whales have blowholes on top of their heads, so they can surface to breathe while keeping most of their body underwater. Whales can stay underwater without breathing for an hour or more because they make very efficient use of their lungs, exchanging up to 90% of their lung volume with each breath, and also store unusually high amounts of oxygen in their blood and muscles when diving.




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