Sunday, April 28, 2013

Underwater Ecosystems and their Importance

By Alex Tribes


There are thousands of species of marine life, from tiny zooplankton to enormous whales. Each is adapted to the specific habitat it occupies. Fish can drink salt water, and eliminate the salt through their gills. Seabirds also drink salt water, and the excess salt is eliminated via the nasal, or "salt glands" into the nasal cavity, and then is shaken, or sneezed out by the bird. Whales don't drink salt water, instead getting the water they need from the organisms they eat.

Microscopic plants and animals called plankton are very important in the ocean because they become food for a lot of animals. They drift along with the currents in the water and are eaten by fish, scallops, anemones, and others. Krill are small creatures that look like shrimp. They eat plankton and are eaten by larger animals, such as whales and birds.

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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