18436-1 (Flora and Fauna of the USA), страница 3

Really very famous and very special for America is alligator. Alligators are an ancient group of reptiles consisting of only two species of the thirty in the order crocodylia. They differ from crocodiles by their teeth in pattern and arrangement, and also somewhat in the shape of their snouts. The alligators lower teeth point upward into pockets in the upper jaw so when they close their mouth only the upper teeth are left showing. The crocodile has both the upper and lower teeth showing, intermeshed. Their fourth tooth back is enlarged so that it may even end up above the upper jaw. The alligator is found only in the area of the upper Yangtse of China and in south eastern United States. It is believed that it may have once have ranged worldwide but was eventually forced out by the crocodile who are more aggressive. The alligators actually live longer than crocodiles but the crocs eat more which may have added to the problem. Alligators withstand cold better than crocodiles. In 65¡F water an alligator will still surface to breathe but a crocodile will sink and drown. For this reason the crocodiles live only in the most extreme south portion of Florida in the United States, while alligators extend their habitat north to the Carolinas, and west to Texas. Crocodiles are the most numerous of all the crocodilians. They take up space in most tropical regions, but the alligator family has a cousin that might help the alligator clan take back its former territory: the caiman. Caimans are even smaller than crocodiles and quite a few live in South America. These buggers have an apatite and temperment similar to the crocodile, and they are slowly taking the place of the crocodile. Unfortunately, the population of all in the crocodilian order has been majorly depleted by man. From 1880 to 1894 two and a quarter million alligators were slaughtered for their skins. Most states in which the alligator resides have laws protecting them but poachers continue to kill them and sell the hides to northern stats at an alarming rate. The Chinese alligator is protected by the government of China, but whether the population is increasing is unknown. Baby alligators were gathered by the thousands and sold in pet stores all over the Unites States so states had to begin controlling their export. Though baby alligator selling has been halted, their cousin the caiman has been sold in even greater numbers, forcing South American countries to place these species under protection and control. Crocodilians of all kinds make bad pets. Regular house hold temperatures are too low for their guts to work properly. This causes the babies' jaws to be deformed, have a humped back, or die after a few months. Even zoo's have a hard time raising the little critters on the right diet. Grown, the beasties are unpredictable. Alligators will eat anything that moves close enough to get grabbed and will get fit in their mouth. These carnivores prefer to swallow smaller things whole. They will eat large things if they have to, and shake them to dismember them.

And of course well known salamander. Salamanders are timid amphibians that look somewhat like lizards without scales. Most salamanders are small, half a foot or less, but the giant salamander of china and Japan can get 5 feet long, and the hellbender of the United States reaches 3 feet. Most salamanders lay their eggs in water but then live on land in rotten logs, caves, or under rocks. Mudpuppies and some other species are the exception to the rule and live their entire life in the water. On the other end, a few species never enter the water at all. Most salamanders have slimy dark skin and are difficult to see in their natural surroundings, but some species are brightly colored. Some brightly colored species let out a milky white fluid that is poisonous to some animals through their skin if they are handled roughly. Salamanders have long tails to help them swim. Most have four legs, but some that live in the water have only the two front ones. A good sense of smell and a long sticky tongue helps salamanders to catch worms and insects. After young salamanders have hatched they are called larvae. They look a little like frog tadpoles, but they have feathery gills on their head. It may take them anywhere from 42 days to 5 years to become adults. Just before they become adults they lose their gills. As adults the salamanders will breathe with lungs through the mouth and skin.

It is really impossible to describe all the divercity of wildlife in America in few pages. There are a lot of encyclopedias, monographies and researches about them and there is still remain a lot of unexplored. The best way to see and study flora and fauna of USA is to come there, join a group of the best friends, take a tent, a bicycal and enough food and go to the unexplored, remoted places in order to see with your own eyes all the diversity and beauty of animals and plants of North American continent.

Список литературы

Climate and Physiography of North America, Luc Brouillet R. David Whetstone , N.Y, 1995

Botany for the next mellenium, Christine Miot , Harward, 1998

Wildlife of the USA and its territories, John K. Francis, New Orleans, LA, 1987

Descriptive fauna of USA and ajacent islands, Lioger H.A., Harward University, 1994

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