Flora and Fauna of the USA
Flora and Fauna of the USA.
To begin the conversation about animals and pland word of North
America is better to start with explanation of climate conditions and
gografical situation of the region, in order to clear understanding of such a
wide diversity of spices.
USA encompasses about 21.5 million km², between latitudes 26°
and 85° N, and longitudes 15° W and 173° E, and it stretches from the Florida
Keys northward to Ellesmere Island, and from Greenland westward to Attu Island
in the Aleutian Archipelago. Widest in the north, the continent narrows sharply
at the Gulf of Mexico. South of the United States border with Mexico, it tapers
gradually to the Isthmus of Panama. It is surrounded by three oceans---the
Arctic, Pacific, and Atlantic, respectively to the north, west, and east---and
by the Gulf of Mexico to the south. It is separated from northeast Asia by the
Pacific Ocean, and by the epicontinental Bering Sea, the Chukchi Sea, and the
connecting Bering Strait. The Greenland and Norwegian seas, as well as the
North Atlantic Ocean, separate North America from Europe and link the Atlantic
to the Arctic Ocean; the Denmark Strait divides Greenland from Iceland. The
Strait of Florida divides North America from the West Indies (Cuba).
Climate, physiography, and geology play major roles in determining
the distributions of present-day soil classes, vegetation types, floras, and
faunas. Biogeographers agree that climate is the primary factor in the control
of these distributions. Climate determines the erosional and soil-forming
processes that occur, and the life forms that are able to survive at a given
locale, all of which may be affected secondarily by the types of bedrock and
surficial deposits encountered in the area. In turn, relief influences climatic
patterns through elevation above sea level and its effects on wind patterns and
rainfall.
Geoclimatic changes that occurred throughout Earth history have
affected the distribution of biotas through time. Climate has changed under
cosmic influences, such as the Milankovitch cycles. The climate has also been
affected by the relative position of the drifting continents, because drift
implies latitudinal shifts, changes in the distribution of landmasses relative
to oceans and oceanic currents, and modifications in the position of mountain ranges
relative to airflow patterns. For instance, the Tertiary opening of the
Atlantic onto the Arctic Ocean, and the establishment of the circumantarctic
current with the opening of the Drake Passage between South America and
Antarctica, played a significant role in subsequent climatic cooling.
The deep oceanic conveyor belt (a bottom sea current that links
all the oceans) was presumably modified by changes in continental distribution
and may have affected climate. W.F. Ruddiman and J.E. Kutzbach (1991) proposed
that the 3-km uplift of the high plateaus in Tibet and in western North America
in the Pliocene-Pleistocene were instrumental in provoking the late Tertiary
trend of climatic cooling. Finally, the pathways by which biotas have been able
to spread between continents were also affected by the existence of bridges.
Such dynamic factors influenced the evolution of life on the North American
continent.
First we take a look about the plant word and we begine by
examining the history of North America vegetation. A discussion of the history
of the vegetation of North America most logically begins with the events of the
late Upper Cretaceous epoch, 70--60 Ma (million years ago). By then, the
angiosperms and other major present-day groups were clearly established as
dominant in the world's terrestrial flora. The continents were closer together
than they are at present, and indeed, Eurasia and North America were still
conjoined across the northern Atlantic. The plate tectonic forces that have
placed the continents in their present configurations, however, were already in
motion.
Our knowledge of the botanical events of the past rests on an
interpretation of the fossil record, which for vascular plants occurs in two
forms. Macrofossils are structures such as leaves, stems, fruits, seeds, wood,
and flowers, whereas plant microfossils representing terrestrial or freshwater
aquatic macrophytic vegetation include pollen grains, spores, and phytoliths
(crystals formed within living plants). Paleobotany (including specialized
approaches such as dendrochronology and analysis of pack-rat middens) has come
to imply the study of plant macrofossils, and paleopalynology designates
studies concerned with plant microfossils.
Experience has shown that most elements comprising a fossil
assemblage are broadly consistent in terms of habitat preference, or they can
be sorted into subsets reflecting habitat diversity (viz., elevational
gradients). This organization gives rise to the concept of paleocommunities
from which it is possible to deduce past climates, paleophysiography, and
biogeographic patterns. Such reconstructions are based on a direct comparison
and presumed general equivalency of most members of a fossil flora with modern
analogs (composition of the flora), on the observation that present-day plants
with certain morphological attributes (e.g., leaf physiognomy) are found in
certain habitats, and on the assumption that most fossil plants with similar
morphological attributes occurred in comparable habitats. For example, modern
plant assemblages containing many large-leaved, entire-margined species with
drip-tips typically occur in humid tropical habitats; therefore, a fossil flora
with many similar leaf types is taken to indicate a humid tropical
paleoenvironment. The composition of a fossil flora, based on the combined
inventories provided by macro- and microfossil remains, leaf physiognomy, and
dendrochronology, are all valuable methods for studying vegetational history
and reconstructing the environments that influenced the development of North
American vegetation through time.
The modern history of systematic botany and floristics in North
America began when the first Europeans landed on these shores and began to
collect objects of curiosity. It is imperative to use the term
"modern," for long before colonization of the New World by Europeans,
the Native Americans, who had arrived millennia earlier, had developed their
own systems of classification, means of identification, and associated
nomenclature. Unlike that of their European counterparts, their knowledge was
transferred by the spoken rather than the printed word and was mostly lost as
their civilizations fell to the invaders. To a great degree, it was not until
the twentieth century that Native Americans were recognized as knowledgeable
about their plants. By then, European thought dominated botany, and the Native
American's botanical understanding was passed on only in an occasional native
name retained in a Latinized form.
It was not until Columbus's second voyage, in 1493, that New World
plants and animals were taken across the Atlantic. For the European scientific
community, the unfamiliar specimens were a source both of great intellectual
curiosity and of philosophical concern. The curiosities were clearly different
from their Old World counterparts, and in some instances they were entirely
novel. The likes and near-likes could be associated, but the distinctly
different were philosophically troublesome.
The Spanish of the early sixteenth century were the first to describe
the flora of the New World. Gonzalo Fernández de Oviedo y Valdes
(1478--1557) visited several of the Caribbean islands and portions of Central
America, trying to fit the tropical vegetation he observed into a
classification scheme that recognized only six species of trees with persistent
green leaves. Oviedo had become acquainted with native New World plants of
equal or even greater value than those introduced to the New World by the
Spanish, and he urged their use. He was ignored.
Nicolas Bautista Monardes (1493--1578) never saw the New World.
His interests were the new medicines and new remedies he felt certain existed.
He classified plants according to their medicinal properties, and for the
American ones he often retained the native names. He accepted treatments
recommended by the Amerinds, but as a firm believer in the Doctrine of
Signatures, he occasionally modified them.
The missionary Jose d'Acosta (1539--1600) spent 20 years in Peru,
returning to Spain in 1588 to publish various works on the New World. He urged
scholars to regard the majority of living things in the New World as unique and
not to assign them established European names. He described numerous native
economic and medicinal plants and commented on the diversity of potatoes, tomatoes,
and chili peppers he had found in the market; he also mentioned cacao and coca.
During this period, intellectual thought often was dominated by
religious dogma. Scholarly investigations in the natural sciences began
primarily in northwestern Europe. The first naturalists often had to flee the
upheavals of the Protestant Reformation and, as a result, many traveled widely
and learned from others. In this way, a more unified system of classification
and nomenclature began to develop.
Herbals, those great tomes illustrated with woodcuts, were the
primary botanical publications of the age. At first they were little more than
restatements of Dioscorides or other classical authors, but as the herbals were
developed over the next two centuries, new species and remedies were
incorporated, including the wonders of the New World. Of equal importance was
the development of botanic gardens, first established in Pisa in 1543. These
soon became centers of scientific importance because not only could plants of
faraway places be seen, but their medicinal properties could be determined
also.
The following discussion begins with the floras of the
Maastrichtian stage of the Upper Cretaceous, 70--65 Ma, and progresses forward
in time through the Tertiary to 2 Ma, the end of the Pliocene epoch, i.e., to
the advent of the Pleistocene, the "Ice Ages." Within each section,
the fossil floras are discussed in a sequence that begins with the southeastern
corner of the continent and proceeds westward and around the continent in a
clockwise fashion.
In describing paleoevents, degrees of latitude and longitude,
unless otherwise noted, are given in terms of present-day locations of the
poles and continents, even though the North American continent has moved
slightly relative to the poles during the Tertiary and to the present.
The flora of North America includes a large number of conspicuous
plants that are called "weeds." The concept of weed is not precisely
defined, for it has both a sociological and a biological component. From the
sociological perspective, a weed is simply a plant that is growing where
someone wishes it were not, and therefore, a weed may be regarded casually as a
"plant-out-of-place." By that definition, a rose growing in a wheat
field would be a weed; a rose in a garden would not. Some plants, however, have
the genetic endowment to inhabit and thrive in places of continual disturbance,
most especially in areas that are repeatedly affected by the activities of
humankind. These plants are biologically "weedy," and they are
sometimes termed colonizing or invasive plants. These biological weeds are the
focus of next paragraph.
Weeds have a measurable effect on the affairs of society, and
therefore they have attracted much attention. Weeds occur in all growth forms
and in many lifestyles. The majority of weeds are flowering plants, and a high
proportion of them share some or all of the following characteristics: short
life cycle, rapid growth rate, high level of energy allocated to reproduction,
efficient dispersal mechanisms, high population growth rate, wide distribution,
seeds with long life spans, and flexible use of environmental resources. He
noted that a plant with but few of these attributes is less likely to be
successful as a weed than is a plant with all or most of them; therefore, the
variation ranges from casual, local weeds to aggressive, widespread weeds.
Botanists assume that species have a "place of origin,"
where at some time the species are differentiated from the ancestral entities.
As time passes, a newly formed species migrates into new areas and/or expands
its range, through the routine mechanisms of seed dispersal, seedling
establishment, and other factors. Undoubtedly, some botanical traffic has
occurred between North America and other continents since antiquity, but
clearly colonization following Columbus's voyages to America initiated a
significant number of invasions. Some of the historical aspects of plant
migration at the hands of humankind are reviewed by V.Muhlenbach (1979).
Foreign or alien species are usually regarded as those that have
been brought to North America by human activities in post-Columbian times,
while native species either originated in North America or had arrived by
various means in pre-Columbian times. Although botanists frequently use the
term "introduced" for these foreign or alien species, in this chapter
the term has a more restricted meaning and refers to those species deliberately
brought by people into a new region, where the plants grow without cultivation.
How many species have been transported from their putative places of nativity
to North America in post-Columbian times is, of course, unknown. The historical
documentation for these plant movements is often not well known or not yet
researched, and many times what is known is based on circumstance and
inference.
Here are en examples of native American plants. A large Sycamore
tree, Platanus racemosa, played
an early role in the establishment of Los Angeles. The central Gabrielino
village of Yangna was located near a 60 ft. high, 200 ft. wide sycamore which
was used for meetings amongst the Gabrielino leaders and was known as the
"council tree". The Spanish settlement that later became the pueblo
of Los Angeles was located next to Yangna, in sight of this stately tree. The
settlement was washed away in the Great Flood of 1815, but the sycamore
survived. It later died in 1892 and was cut down. A ring count revealed that
the tree was 400 years old. It had started its life about the time Columbus
first landed in America. Cottonwoods were very common trees along rivers and
arroyos in California and the southwest. As cities and farmers have lowered
water tables, these riparian trees have disappeared from many banks along
arroyos in California, Nevada, and Arizona. The Fremont Cottonwood, Populus fremonti, was discovered in 1844
near Pyramid Lake by Major John Charles Fremont and Kit Carson. They used its
riparian nature to help locate water. Willows are also a common riparian tree
in the southwest. Some are actually assisted by floods. The rushing water bends
some branches down into a sand bar where they sprout new roots and plants. The
Willow, Salix, leaves were used
by Native Californians for medicine. The small branches were used for baskets,
and the large branches for wood. Cattail, Typha
domingensis. California Indians used the roots and pollen for food,
the roots for medicine, and the stalks for bedding and house construction
material The Coastal Live Oak, Quercus
agrifolia. An organization was created to promote its protection
and replanting. Spiny Clotbur, Xanthium
spinosum , uses its spines to transport the seeds long distance
with the help of animals who brush against it. Gourds found in the Sepulveda Basin.
During major winter storms these plants may be under the floodwaters that are
held back by the dam.
Common Sunflower, Helianthus
annuus.Native Californians used the seeds for food and the roots
for medicine. 
Duckweed, and two Bluets, if you
can see them. Bluets are common along the river. Reeds and grasses were used by
native americans for baskets, cordage, and food from the seeds. Jimson Weed was
used by Native Americans as a ritual drug. It can be poisonous to humans and
animals.
Our next pages we will devote to the world of animals of USA.
Which animals are really special for the North America? One of the is coyot.
The ghosts of the woods. The ever present monolog. The infamous cries of the
coyote sparks tremors of terror in rural dwellers. Few Westerners regard the
Canis Latrans as anything more than a savage nuisances. But even its enemies
concede its durability. It thrives in the face of all attempts to trap, poison,
or blast it into oblivion. The settling of the Great Plains is expanding its
range eastward to the Atlantic, partly because of extirpation of the wolf. New
Englanders call it the "coy dog" or brush wolf. But it's still the
same mythical coyote of lore and legend. The mane "coyote" comes from
the Aztec word "coyotl." Its Latin name means "barking
dog." Adults, 2 feet high at the shoulders, are 3.6 to 4.5 feet long and
weigh 20 to 50 pounds. The tough and wiry appearance of the coyote is
misleading to its keen senses and quick wit. The coyote adapts readily to
almost any habitat. And it is fast--up to 30 miles an hour in a dead run.
Coyotes hunt alone or team with others to scrounge a meal. They will eat
anything--from rabbits, rodents, and carrion (most of their diet), to
watermelons and insects. Coyotes mate for life, and the female bears five or
six pups each spring, and both parents share in their upbringing.
The other is jaguarundi.Hued like the desert dusk, the long
low-slung jaguarundi can stalk unseen in the half-light. Twilight and dusk are
its most successful hunting times. This small-headed southern felid, in body
composition, resemble the weasels about as much as it does fellow cats. Tail
down, it moves sinuously through the brush with scarcely a ripple of leaf or
twig to betray its presence. One pounce, and a bird in the brush is a bird
consumed. Though an agile climber, this species spends less time in the trees
then the ocelot. Preferring to hunt on the ground, it needs no leaf or limb pattern
on its black or russet coat. Dark plain fur serves as more than adequate
camouflage when hunting fish and small mammals. The jaguarundi is one of the
least known cats on the continent, its life history and population not yet well
documented, and now may be too late. Already a rare animal, it becomes even
more rare as its habitat--wild thickets and lowland forests--is sheared for
ranching and farm use. Mating time for this cat seems to vary with location.
The litter of two to three kittens is born after a gestation period determined
from captive animals to be 72 to 75 days. Like most other cats, kittens in the
wild are probably cared for solely by their mother. Full grown, the jaguarundi
stands up to 14 inches at the shoulders. Its tail accounts for nearly half its
length of 35 to 55 inches. A large individual may weigh as much as 20 pounds.
The same cat spice as a jaguarundi is ocelot. Marbled to blend
into their sun and shadow world, Ocelots wear beautifully marked coats of
brown, black and cream. Unfortunately, the marked coats make them a marked cat.
They, like many other spotted cats of the south, were heavily hunted. The
United States has protected this cat by passing the Endangered Species Act and
making importation of their fur illegal. Some Latin American countries also
officially protect these rare cats. Living in forests and brush land, Ocelots
usually sleep during the day, hidden in foliage, and at night hunt medium-sized
prey: rabbits, birds, monkeys, pacas, agoutis, iguanas, fish and frogs. A male
and female sometimes hunt together. An excellent climber, the Ocelot will often
take to the trees when pursued. Ernest Seton, however, wrote "He can run
like a fox, blind hop, back-track, and double-cross his trail." Mexicans
who hunted Ocelots not only took the pelts, but also consumed the meat and
blood. In legend, eating Ocelot flesh brought great strength and health. This
legend may have derived from the fact that if you were lucky enough to capture
and eat an Ocelot, you were already in extraordinary health.
In cooler parts of their range Ocelots tend to bare their young in
spring; in tropical areas births occur randomly. A cave or hollow tree is the
ideal den. Information on this elusive species is limited. An average litter is
probably two or three. An Ocelot is 36 to 54 inches long, including a tail of
11 to 16 inches to form 1/3 of its total length.
From the Ursidae family everybody know grizzly.
"Grizzly" means "grayish" and also "inspiring
horror." Both meanings apply. The grizzly's thick, coarse fur varies in
color - off-white, tan, yellow, brown, black. In the Rockies the typical hue is
dark brown with a grizzly frosting on the back, source of the nickname
"silvertip." It is also called the brown bear. Naturalist George Ord
put the second meaning of grizzly into a scientific name (horribilis) after
reading of Lewis and Clark's adventures with this "tremendous looking
animal."
For years Ursus horribilis was classed as a North American
species; today it is considered a race of the circumpolar brown bear, U.
arctos. Most authorities classify our grizzlies and mainland bears as one
subspecies, U. a. horribilis. Another race, U. a. middendorffi, called the
Kodiak bear, inhabits Kodiak and two nearby islands in the Gulf of Alaska.
Grizzlies average about twice the weight of the black bear, weighing 600 to 800
pounds (272 to 363 kg) as adult males. But size may not offer a good clue to
the identity of a lone bear spotted on a distant trail. Where does the bear
loom tallest? At the shoulders? The hump of muscle there identifies the
grizzly. Farther back, toward the rump? Then it's a black bear. Grizzlies mate
in late spring. Cubs, usually two weighing about 14 ounces (397 g), are born in
the winter den; they stay with mother some 18 months. She becomes sexually active
as contact within the family group declines and she leaves the cubs. Or she -
or her mate - may even run them off. Roots, leaves, and berries form the bulk
of the diet, but grizzlies also relish meat: squirrel, elk, moose, deer -
whether freshly killed or carrion. They feed in garbage dumps and pay the price
of eating humans' sugary food: tooth decay. At times they prey on cattle. They
avoid humans - but not always, and with tragic results for both. The grizzly
has been eliminated from parts of Canada, Mexico, and the United States. It
bestrides the flag of California but is gone from there. South of Canada is has
some protection as a threatened species. Even so, it is often shot as a threat
to people and livestock. With habitat loss and the growing human presence in
the northern Rockies, grizzly survival even is national parks depends upon
research and wise management. Yet the grizzly remains a force, a symbol of
untrammeled nature: "He is a dignity and power," wrote outdoors man
Andy Russell, "matched by no other in the...wilderness."
We should not also forget that USA has a very big coastal line.
That means that we must eximine the marine life also, because it is one of the
part with a ll American life consist of. So…One of the most famous animals is sea
otter. Lolling on a kelp bed along the Pacific Coast, shielded from frigid
water by luxurious fur, the sea otter seems to lead an easy life. Its ancestors
once lived on land. After taking to the sea eons ago, they did not develop a
blubbery layer beneath the skin, as whales did. The otter depends for
protection from the cold on the blanket of air trapped in its densely packed
fur, a fur so fine is almost doomed the species. Said Captain James Cook after
acquiring some pelts from Nootka Indians in 1778: "The fur of these
animals . . . is certainly softer and finer than that of any other we know of
." Sea otters were already being killed for their pelts by Europeans,
Asians, and North Americans. Cook, China-bound, took furs with him. The demand
and the slaughter grew. The fur trade nearly wiped out the species. In 1911 the
United States, Great Britain, Russia, and Japan agreed to stop the killing. The
near-shore animal has made a substantial comeback in the Aleutian Islands and
off the California coast south of Monterey. It shows promise where it has been
transplanted. The sea otter, 4 to 6 feet long (122 to 183 cm), usually weighs
33 to 66 pounds (15 to 30 kg), but may reach 100 pounds (45 kg). The male is
the largest North American mustelid. Females are about 20 percent smaller.
Adults first breed at about four years, courting and mating in the water. A
single pup - rarely two - is born six to eight months later. With no margin for
error in a litter of one, the newborn is better developed than most mustelid
pups, arriving eyes-open with a mouthful of milk teeth. For a year the pup will
nurse, nap, and be groomed. Its mother will carry it on her chest while she
swims on her back. Males usually live apart. Grooming is not a mere nicety. If
the otter’s coat - containing some 800,000,000 fibers - gets soiled or matted,
the trapped air is lost and with it buoyancy and insulation. Oil spills and
other pollution - and competition with commercial fishermen for some of its
favorite foods - are among the problems that still menace the otter.
Surprisingly it exist not only sea otter in America , but also
river otter. The engaging river otter cavorts in and out of water through most
of the United States and Canada, appearing to enjoy life thoroughly. It can
live near people and seems to like showing off for an audience. The otters
sleek, streamlined body, with short legs and webbed feet, enables it to swim at
speeds reaching seven miles an hour. Adults are as long as 511 inches (130 cm),
including the fleshy, tapered tail that serves as a prop on land, a rudder or
oar in water. Otters mate in the water, usually in winter or early spring. Male
and female then go their separate ways. One to five pups are born nearly a year
later in a riverbank den the female prepares - perhaps after evicting a muskrat
or beaver. At about 12 weeks, the young venture out of the den. Soon they are
swimming and expertly hunting their favorite foods - fish, crayfish, frogs,
insects, and small mammals. This adept aquanaut can easily dive to 35 feet.
Flaps of skin close its nose and ears and its pulse rate slows, allowing it two
minutes underwater before it must pop up for air.
It must be dangerous but North America is also the home of
Scorpions. Scorpion poison is usually used in capturing food. With their claws,
scorpions capture insects and immobilize them with their venom. Sadly,
sometimes people get stung when scorpions defend themselves, or when disturbed
or annoyed. Similar to the spider's venom, scorpion venom injures the soft body
parts or nervous system of the prey. Many people think that a scorpion sting
causes death, but in truth, few species produce this reaction. As a matter of
fact, many people have been stung by scorpions and survived to relate their
story. In the US only Centruroides sculpturatus causes death, though other
sings may be compared to that of a bee sting. Number of deaths caused by
scorpions increase rapidly in countries of India, Pakistan, or other dry areas.
Because they weigh less than adults, most fatalities are that of young
children. Media exaggeration of this causes fear from the public. According to
fossils, the scorpions' appearance have changed little over 350 million years.
A fossil found in Scotland suggests that scorpions were twice as large then as
they are today. Gigantoscorpio (the fossil) is 16 inches long while the largest
alive today is 8 inches. Maybe the fossil is a remainder of an extinct scorpion
species. There are more than 700 different kinds of scorpions. Five families of
scorpions live in the United States. Buthidae makes up the largest of these
families, consisting of over 300 species. It also makes up many of the species
which are dangerous to man. Vejovidae is the most common family of scorpions
found in the US. An exoskeleton makes up the hard outer surface of the
scorpion, and sensitive hairs on this exoskeleton detect vibrations (just like
spiders). Molting occurs so that the scorpion may grow to its full size. Furst,
a new exoskeleton is produced underneath the old one, and the outer shell splits
off. Then, the new soft exoskeleton bends and stretches into the new size
before hardening. Like the spider, scorpions possess two main body parts; the
cephalothorax which is basically the thicker part connecting to six pairs of
appendages, and the abdomen which includes a tail with the sting protruding
from the end. Most species range from one half to eight inches. The first pair
of appendages include insignificant pincers. Large claws on the second pair
seize and crush prey while legs make up the last four pairs. Their head
consists of six to twelve eyes usually, and a breathing hole commonly located
on the abdomen. Reproduction differs between spiders and scorpions. Rather than
laying eggs, scorpions bear live young which cling to the mother for an amount
of days. In courting, scorpions start with a dance of "holding hands"
and walking around, every once in a while bringing mouth parts close for a
"kiss." Next, the two jerk their bodies without leg movement. After
this, the two tails curve over their backs to touch and even entwine with the
other's. This now resembles a fight. Here's what is actually happening. In 1956
a scientist discovered this process to be the male fertilizing the eggs.
Spermatophore, the small sperm packet, is glued to the ground by the male. He
then leads the female to it, and they walk back and forth till she finds it
with her genital opening. Often after this ritual the female will eat the
unlucky male. Scorpion eggs stay inside their mother from four months to a
year. When they come out, they are surrounded by a thin white sac, soon
breaking open to soft shelled babies which cling to their mother. She doesn't
feed them, but they take care or themselves after the first molt, several weeks
later. When stinging prey, the scorpion curves its tail over its head and
thrusts it into the victim in a whip like fashon. The sting wound causes a
burning sensation, and closes up directly after the stab to prevent any poison
loss. Area will become swollen and discolored resulting with a blister. Effects
worsen without treatment which is why receiving medical attention is important.
Hunting at night, spiders and insects make up their main diet. Also, being
exposed to ultra-violet, these are fluorescent, and easy to spot by night with
use of black light. On the end of the tail, the sting organ is made up of two
glands which hold the poison.
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
Для
подготовки данной работы были использованы материалы с сайта http://www.easyschool.ru/