Tuesday, November 20, 2007

Desert ecosystem










The desert ecosystem is one full of interesting questions. How can anything survive in a place with hardly any water? Why is it so dry to begin with? . But first, let's explain what a desert really is.
You can find at least one desert on every continent except Europe and Antarctica. Each desert is different in some way, but they all have one thing in common. In order for an area of land to be considered a desert, it must receive less than 10 inches of water a year.
How come deserts get such little water? There are few
clouds in these regions, and we all know that without clouds, there can't be rain or any other precipitation! But clouds also serve another purpose - they block out some of the Sun. The desert gets mighty hot during the day because the Sun beats down on the sand. At night, the desert gets very cold, because there aren't clouds around to keep the heat from escaping to the atmosphere.
There are plenty of differences between the deserts of the world. Some deserts are made of very fine, red sand, others consists of sand mixed with pebbles and rocks. The desert sand started out as rock, but years of
weathering by wind and water has created dunes in the deserts. These sands are mostly minerals, and sometimes oil can be found hidden deep within the rocks.
So, what kinds of plants and animals survive in these vast drylands? Are deserts of any use to humans? like :
plants, insects and arachnids, reptiles, birds, mammals andcamels .















Plants



Surprisingly, there are many species of plants that survive in the desert. Most of them are succulents, which means they store water. Others have seeds that lay in the sand until rain comes. Regardless, these plants find a way to get water and protect themselves from the heat.
The most famous desert plant is the cactus. There are many species of cacti. The saguaro cactus is the tall, pole shaped cactus you see on television. The saguaro can grow up to 40 feet tall. It can hold several tons of water inside its soft tissue. Like all cacti, the saguaro has a thick, waxy layer that protects it from the
Sun.
Other succulents include the desert rose and the living rock. This strange plant looks like a spiny rock. It's disguise protects it from predators. The welwitschia is a weird looking plant. It has two long leaves and a big root. This plant is actually a type of tree and it can live for thousands of years.
There are many other kinds of desert plants. Even in the worst conditions, these plants continue to thrive.






Insects and Arachinds






You can find insects almost anywhere in the world. So it should be of no surprise that there are plenty of insects in the desert. One of the most common and destructive pests is the locust. A locust is a special type of grasshopper. They travel from place to place, eating all the plants they find. Locusts can destroy many crops in a single day.
Not all desert insects are bad, though. The yucca moth is very important to the yucca plant, because it helps pollinate it. The darkling beetle has a hard, white, wing case that reflects the
Sun's energy. This allows the bug to look for food during the day.
There are also several species of ants in the desert. The harvester ants gather seeds and store them for use during the dry season. And the honeypot ants have a very weird habit. Some members of the colony eat large amounts of sugar, so much that their adomens get too large for them to move! The rest of the colony feeds off this sugar.
There are also arachnids in the desert. Spiders are the most notable arachnids, but scorpions also belong in this group. Some species of scorpions have poison in their sharp tails. They sting their predators and their prey with the piercing tip.






Reptiles






Reptiles are some of the most interesting creatures of the desert. Reptiles can withstand the extreme temperatures because they can control their body temperatures very easily. There are two main types of desert reptiles: snakes and lizards.
Many species of rattlesnakes can be found in the desert. Rattlesnakes have a noisy rattle they use to warn enemies to stay away. If the predator isn't careful, the rattlesnake will inject venom with its sharp fangs. Other desert snakes include the cobra, kingsnake and the hognose.
Lizards are probably the most bizarre looking animals in the desert. While some change colors and have sharp scales for defense, others change their appearance to look more threatening.
One such creature is the frilled lizard. When enemies are near, the lizard opens its mouth, unveiling a wide frill. This makes the lizard look bigger and scarier. The shingleback has a tail with the same shape as its head. When a predator bites at the tail, the shingleback turns around and bites back!
There are only two venomous lizards in the world, and one of them is the gila monster. It has a very painful bite! If you see one, it's best to get away!






Birds






Like the other creatures of the desert, birds come up with interesting ways to survive in the harsh climate. The sandgrouse has special feathers that soak up water. It can then carry the water to its young trapped in the nest.
Other birds, like the gila woodpecker, depend on the
giant saguaro as its home. This woodpecker hollows out a hole in the cactus for a nest. The cool, damp inside is safe for the babies.
The roadrunner is probably the most well known desert bird, thanks to the cartoon. Roadrunners are so named because they prefer to run rather than fly. Ostriches also prefer to use their feet. Even the young depend on walking to find food and water.
The galah is one of the prettiest desert birds. It is one of the few species that return to the same nest year after year. Galahs are interesting birds, in that the number of eggs they lay depends on the climate.






Mammals






There are several species of mammals in the desert. They range in size from a few inches to several feet in length. Like other desert wildlife, mammals have to find ways to stay cool and drink plenty of water.
Many desert mammals dig holes in the ground and stay there during the hot days. They return to the surface at night to feed. Hamsters, rats and their relatives live in holes. Not only do the burrows keep the animals cool, they are also a great place to store food.
Of course, not all animals live in holes in the ground. The kangaroo and spiny anteater both live in the Australian desert region. Spiny anteaters are unusual mammals because they lay eggs.
The desert is also full of wild horses, foxes and jackals, which are part of the canine family. And we can't forget the cats. Lions are found all over the deserts of southern Africa.






Camels



Camels could be included in the mammal section, but they are such an important part of the desert we devoted a whole page to them! Camels are the cars of the desert. They are the main transportation for people that live in the desert.
There are two types of camels: bactrian and dromedary. The main difference between the two is the number of humps. Dromedaries have one hump, and bactrian have two. Both kinds are used by people, but only bactrians are found in the wild.
Camels are used because they need very little water. Camels can withstand very high temperatures without sweating. They also store fat in their humps for food. If a bactrian camel travels a long distance without eating, its hump will actually get smaller!








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