Monday, April 29, 2013

Discover an Underwater Ecosystem

By Alex Bradey


Technology brought the study of marine biology to new heights during the twentieth century. In 1934 William Beebe external (1877-1962) and Otis Barton external descended 923 m/3,028 ft below the surface off the coast of Bermuda in a bathysphere external designed and funded by Barton. This depth record was not broken until 1948 when Barton made a bathysphere dive to 1,372 m/4,500 ft. During the interim, Beebe was able to observe deep sea life in its own environment rather than in a specimen jar. Although he was criticized for failing to publish results in professional journals, his vivid descriptions of the bathysphere dives in the books he published inspired some of today's greatest oceanographers and marine biologists.

Many marine mammals live in very cold water. They have blubber to insulate their bodies and keep them warm in the cold ocean waters. Blubber is a really thick layer of fat between the animal's skin and inside organs. It is very effective at keeping an animal warm. The gray whale's layer of blubber is about 10 inches thick!

Sharks look a lot like marine mammals, but they are actually fish! Unlike most fish though, sharks do not have bones. Their skeletons are made up of cartilage instead of bones. Cartilage is the same stuff that makes your ears and the tip of your nose have their shape and be a little bit flexible. Even though they don't have bones, sharks do have lots of other similarities to bony fish. They are cold-blooded and breathe through gills instead of through lungs. Sharks have gills on each side of their heads. As they swim, water passes over the gills and oxygen flows in from the water.

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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