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Severe lack of vegetations, rainfall and infertile
ground are common for all deserts. When we talk about deserts we mostly
think about the terribly hot sea of sands with no life around. But
not all deserts are full of hot sands. There are cold deserts as well with
snow covered land stretching for hundreds of miles with no vegetations or
apparent sign of life, save a few stray patches of thorny plants.
Hot Deserts:
These are seen around the tropical
belts in Africa, Middle East, part of Indian subcontinent, southern
parts of North America, and parts of north Australia. With too
little rain to keep the covering plants alive makes life in deserts
real tough. Those who survive do so by resorting to some strange
adaptive techniques. While some deserts are sandy, some consist of
stones and rocks with stray pockets of sand. Some are plains; while
some are ridged by steep-sided rocks and mountains. Though most are
fiery hot at daytime and cools off after sunset, there are few where
icy north wind blows all through. Mostly short thorny trees and
bushes known as cactus, and hay like weeds sprout at some places in
the sand.
Animals and birds find food and cope with heat and drought in
various ways. All their bodies have a built in mechanism to procure
and retain the moisture needed for survival from the harsh
surroundings. Deserts are infested with a wide variety of insects, lizards, snakes
and small creatures.
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Among the smallies are tiny crustaceans, like woodlice with humped
backs that shade their bodies from the sun.
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When rain fills hollows,
tiny tadpole-like Triops as also some frogs hatch from eggs laid long ago. They lay
eggs. But their life span stretches about two weeks after which the
pools dry up and they too die. Only their eggs survive to be
self hatched in the sand.
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The desert butterflies and moths also pass
the dry season as pupae and are woken up by the rains. They grow up,
lay eggs and die. Everything is complete by the time the plants dry
up fully. Desert locusts are huge grasshoppers. They sometimes fly
in dense clouds seeking leaves to eat.
Certain beetles survive 17 years of drought by consuming only dry
plants and dung.
Among other insects come the scorpions and spiders. Scorpions spend
hot days in crevices or holes dug under stones, among tree roots or
by dry dry streams of rivers. They seize insects that stray in. At
night these hunters emerge for making a kill for their meal.
The sun spiders or camel spiders also seize insects with their
pincers. They have huge jaws but lack the poison with which most
spiders kill their prey.
The bold wolf spiders hunt in the open. Keen-eyed jumping spiders
detect and creep up on their prey from a distance. Then pounce on
them like cats.
The desert reptiles feed on the insects and spiders. The reptiles'
waterproof skins retain body moisture and bodies release little
water as waste. But they prefer hunting at night, or at dawn and
dusk. Because long exposure in the hot tropical sun could kill the
reptiles. Most lizards including the collared lizard prey on
insects. The chuckwall wedges and spiny tailed lizards feed on
plants. These have no poison. But the orange and black Gila monster
relies for defense on poisonous fangs and bright warning colors.
Slithering over hot sand is a problem for snakes. Some flow along in
looping movement, lifting part of their body into the air. Thus
while moving they do not sink in the sand and keeps part of its body
off the hot ground. The horned viper and sidewinder rattlesnake move
in this way. Both quickly burrow into cool sand when the sun becomes
too hot. Among others, rattlesnakes, vipers and some cobras flourish
in deserts. The speckled, multicolored coral snakes eat other snakes
and lizards.
Desert tortoises are seen in the American desert. By the time the
sun rides high, tortoises have retreated to cool, dark holes in the
ground. And come out only when sun sinks.
Most small mammals are rat-sized rodents and include the
similar-looking jerboas of Africa and kangaroo rats of North
America. Asleep underground, ground squirrels survive hot desert
summers.
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Most desert rodents including kangaroo-rats, pack rats,
pocket mice and white footed mice eat seeds or other dry foods. But
African sand rats munch salty succulent plants.
Hunting the rodents
are carnivores such as foxes, jackals, coyotes and skunks. The
African fennec foxes get all the moisture they need from juices in
their victims' bodies. |
Big ears serve as radiators that help to
prevent the foxes overheating. The jackrabbit's giant ears also help
in the same way.
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Among the larger mammals, camels are called the 'ship of the desert'
for their ability to go without water for weeks together. The hump
on the back stores the extra fat so they may do without food and
water for a long time. They lose little water as urine and start
sweating only when the temperature exceeds 40 C. Their eyes are
heavily lidded so as to protect them from the blinding storms. The
feet are heavily padded to stand the hot sand. All these have
equipped the camel to travel long through the desert.
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Wild asses, too, can live a long time without water. Oryxes usually
get what water they need from plants and dew. Their long thin limbs
help them to radiate spare heat from the body.
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desert animals
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