РефератыИностранный языкCoCoral Reef Essay Research Paper The modern

Coral Reef Essay Research Paper The modern

Coral Reef Essay, Research Paper


The modern understanding of coral reefs begins in Charles Darwin’s book, On the


Structure and Distribution of Coral Reefs. In this classic book written in 1842, he


distinguished three main types of reef: the fringing reef, the barrier reef, and the atoll.


The fringing reef occurs near the shoreline and basically follows the profile of the


shore. Its stony corals need a firm base on which to establish themselves, and they must


compete with many other sedementary organisms looking for a firm substrate on which to


settle. In off-shore waters, that substrate is usually provided by the limestone secreted by


earlier stony corals on rock (often volcanic). However, if there is a firm, rocky base


present, as in fringing reefs, sedentary rivals can settle in great numbers without waiting


for reef-building corals to lay the foundations (Stafford-Deitsch 20). Thus, the stony


corals do not have to be the major constituents of the reef. Sponges, soft corals, and


corraline algae are abundant throughout the fringing reef.


Some of the finest fringing reefs in the world are along the edges of the Red Sea,


where the conditions are premier for the growth of the reef. The water is enclosed by


desert. Therefore, there is barely any rainfall to wash either the sand or fresh water into


the sea. Also, there are very little clouds in the area allowing sunlight to reach the surface,


resulting in much warmer water than one might think to find at this latitude. The reefs in


the Red Sea are some of the richest and most diverse. If one were to swim over the crest


(the open-water edge), one might panic being that the reef drops drastically into unknown


depths. Thus, not allowing wave action to stir up much sediment which would damage


the reef being that the sediment settles below the reach of the waves. Little sediment at


the top of the reef causes water to be clear, maximizing the amount of sunlight that


reaches the reef (Stafford-Deitsch 21).


The second type of reef according to Darwin is the barrier reef. It is different than


the fringing reef in one main way: the area between the living coral of a fringing reef and


the shore is the reef flat, but the area between the barrier reef and the shore is a lagoon


(Stafford-Deitsch 21). The lagoon is a relatively shallow area of water, only a few meters


in depth. However, its width can be enormous as in

Australia’s Great Barrier Reef, some


forty miles wide.


The final type of reef distinguished by Darwin was the Atoll. It is a more-or-less


circular crest of coral with a lagoon located at its center, only about a few kilometers in


diameter. They are usually far from human influence and very deep, making them ideal for


diving. There might be areas on an atoll reef where sand is exposed to the air. The reef


acts like a trap for sand and with the occasional storm, and persistent currents, banks of


exposed sand and small sand islands can be formed.


Coral is formed in an astonishing way. The animals that form coral belong to the


same animal group as the hydras, jellyfish, and sea anemones. Most individual coral


animals, polyps, are less than one inch in diameter, but a small percentage of them measure


one foot. A coral polyp has a cylinder-shaped body with a mouth surrounded by tentacles


at one end, and the other end is used to attach itself to the hard surfaces at the sea bottom.


Most coral polyps live in colonies. The stony corals attach themselves to each other with


a flat sheet of tissue that connects to the middle of each body. Half of the coral polyp


extends above the sheet and half below. The polyps build their limestone skeletons by


taking calcium out of the seawater. They than deposit calcium carbonate (limestone)


around the lower half of the body. As new polyps grow, the limestone formation becomes


larger and larger.


The polyps feed primarily on tiny swimming organisms like the larvae of many


kinds of shellfish. Reef corals cannot live without algae. They use some food


manufactured by algae that live in the polyps’ own tissue. These algae produce chemicals


that help the coral animals secrete their limestone skeletons. Coral reefs grow only in


water with enough light for photosynthesis to occur in the algae.


Coral polyps reproduce either form eggs or by budding. Small, knoblike growths


called buds appear on the body of an adult polyp, or on the connecting sheet from tome to


time. These buds grow larger, separate form the parent, and begin to deposit their own


limestone in the colony making it grow. New colonies of coral polyps form when the


adult polyps of an old colony produce eggs. These eggs grow into tiny organisms that


swim away. The animal than settles to the sea bottom and begins to form new colonies by


budding.

Сохранить в соц. сетях:
Обсуждение:
comments powered by Disqus

Название реферата: Coral Reef Essay Research Paper The modern

Слов:885
Символов:5574
Размер:10.89 Кб.