Blue+Coral-extinct

By Elizabeth Poon 10C

==== The Rugosa are an extinct group of corals that were abundant in Middle Ordovician to Late Permian seas. Solitary rugosans are often referred to as "horn corals" because of their characteristic shape. However, some species of rugose corals could form large colonies. Other animals that live in sea includes sea urchin, sea otter and turtle ====

The following report shows that the ancestor of coral and adaptations that lead them to extinction.

 * Kingdom || Animalia ||
 * Phylum || Cnidaria ||
 * Class || Anthozoa ||
 * Subclass: || Zoantharia ||
 * Order: || Rugosa ||



__** Habitat: **__
==== Rugose/Rugosa corals are corals that live in the Mississippian period. In this period, this coral could be found in near abundant in Middle [|Ordovician] to Late [|Permian] seas. They rely on cool and shallow water. ==== ==== The study of western European rugose coral habitats from the base of the Tournaisian stage to the Serpukhovian stage allows the recognition of four basic habitat types, which can be divided into a total of 11 subtypes. Colonial rugose corals are widely encountered in Mississippian bioherms where they are dwellers, form capping beds support framework building along with other organisms and form coral framework. ==== ==== Horn corals were one of the Rugosa Coral and were abundant during the Mississippian During this time, Utah was almost completely covered by a shallow sea. Abundant horn coral fossils can be found in the Confusion Range in Millard County. ====

__** Structural Adaptation 1 **__
A common characteristic of rugose corals, from which they get their name, is the wrinkled appearance of their outer surface. (Rugose comes from the Latin word for wrinkled.) Rugose corals may be either solitary or colonial. Because solitary rugose corals are commonly shaped like a horn, these fossils are sometimes called horn corals. died out in the [|major extinction] that occurred at the end of the [|Permian Period,] roughly 250 million years ago. This extinction marked the end of the [|Paleozoic Era.] The corals that inhabited the post-Paleozoic seas differ significantly from the earlier corals. Because of this, many specialists argue that these later corals may not be closely related to the Paleozoic corals.

__** Behavioral adaptation 1: **__
The earlies grades of organizing the corallite appeared during the Middle Ordovician. They had only simple septa, tabulae and walls. Calyx is the coral polyp that lived on top of a tabula in a depression. A layer of thicken calcite (marginal stereozone) then developed around the periphery of the corallite. This would enable the Rugosa coral to strengthen function for defensing.

__** Behavioral adaptation 3 **__
The emergence of colonial forms, adaptive radiation and exploitation of both solitary and colonial reef habitats are in the period of early Silurian. During this period, dissepiments (small horizontal internal blister-like plates) appeared in several lineages. These dissepiments strengthens the function of Rugosa coral and make incremental growth of corallite possible, so there is no need to lift the whole polyp to create an entire new tabula. Nevertheless the Rugose corals remained subsidiary components of reefs relative to tabulate corals and stromatoporoids.

__** Behavioral adaptation 3 **__
Another behavioral adaption is that the Rugosa coral was adaptive to radiation. Coral faunas were seriously affected by the late Devonian mass-extinction events. During the early period of [|Carboniferous], a new adaptive radiation occurred in both solitary and colonial forms of corals. At this time a number of types developed a column through the middle of the corallite (through a thickening of the end of the counter septum) called the columella. It is assumed this would also aid in strengthening and growth of the structure. In addition the microstructure of the skeletons became quite complex. The Rugose corals of this period were therefore the most advanced types that evolved.

__** Physiological adaptation 1 **__
Rugosa corals possessed stinging cells to capture prey and food. They also had tentacles to help them catch food and prey. Some corals eat zooplankton (tiny drifting animals) or small fishes. Others consume organic debris. Many reef- building corals derive their nutrition from zooxanthellae [|.] Coral polyps are generally nocturnal feeders. At night, they extend their tentacles to capture food with the aid of nematocysts.



**__ Selection pressure __**
Why did the rugosa corals go extinct? The main reason is because rising of sea levels. After the Ice Age, the melting of glaciers and ice cause the sea level to rapidly rise. Rugosa corals live in shallow water with a cool temperature. As time goes by, the sea is being polluted by humans thus increasing the temperature of water and the corals are affected with diseases. Many people said that Rugosa corals are carnivores but until now, there is still no evidence that is able to prove that.

** Threats to reefs: **
A wide variety of human activity has damaged almost all of the world's coral reefs. Human damage also weakens the reefs' ability to recover from natural disasters. As human communities dependent upon the reefs for food, income, medicine, and coastal protection, the natural habitat of the coral is destroyed and therefore affecting the Rugosa’s living environment. Ocean pollution poisons coral polyps. Pollution takes on many forms including oil slicks, pesticides and other chemicals, heavy metals, and garbage.

References:
Clarkson, E. N. K., 1979, Invertebrate Palaeontology and Evolution, 3rd Edition: London, Chapman and Hall, 434 p. Fortey, Richard, 1999, Life--A Natural History of the First Four Billion Years of Life on Earth: New York, http://www.fossilmuseum.net/Tree_of_Life/PhylumCnidaria/classanthozoa.htm Hill, Dorothy, 1981, Coelenterata, Anthozoa, Subclasses Rugosa and Tabulata; in, Treatise on Invertebrate Paleontology, Coelenterata, Supplement 1 (Rugosa and Tabulata), Part F, v. 1-2, Teichert, C., ed.: Boulder, Colorado and Lawrence, Kansas, Geological Society of America and The University of Kansas, 762 p. Johnson, Kirk B., and Stuckey, Richard K., 1995, Prehistoric Journey--A History of Life on Earth: Boulder, Colorado, Denver Museum of Natural History and Roberts Rinehart Publishers, 144 p.  Moore, Raymond C., Lalicker, Cecil G., and Fischer, Alfred G., 1952, Invertebrate Fossils: New York, McGraw-Hill Book Co., 766 p.  Nudds, J. R. 1979. Coloniality in the Lithostrotionidae (Rugosa). In Biology and Systematics of Colonial Organisms (G. Larwood & B. R. Rosen, eds.) pp. 173-192. Academic Press: London.University of Newcastle, Department of Geology, 1998, Rugose and Tabulate Corals: Stanley, George D., Jr., and Fautin, Daphne G., 2001, The Origins of Modern Corals: Science, v. 291, p. 1913-14. University of California Museum of Paleontology, 1994, Introduction to the Tabulata: www.ucmp.berkeley.edu/cnidaria/tabulata.html (4/12/00).