Survival of dromedary
camel in harsh and hostile environment (hot weather conditions) is the salient
feature of this unique animal. It has adapted mechanisms that allow it to withstand
prolonged water deprivation, high temperature, especially in the absence of
readily available water, and survive when feed resources are scarce or of poor
quality. Heat tolerance is in part due to its’ ability to minimize water loss. The
camel retort to hot arid conditions by reducing urine production, absorbed
urine, sweating economically, by an increase body temperature and by the
‘storage’ of CO2 and glucose in the muscles. Camels can survive up to 14 days
without water and can tolerate water losses of up to 30%. A camel may drink
more than a third of its body weight as it rehydrates.
In terms of actual water
intake, camel drinks 200 to 220 L in 3-10 minutes. In other animals rehydration
at these levels would lead to over hydration and possible death. The camel is
able to do this as large amounts of water can be stored for up to 24 hours in
the gut to avoid a rapid dilution of the blood. The camel’s kidneys play a
major role in the process of conserving water, having strong capacity of water
reabsorption and excretion of very concentrated urine
The camel’s blood plays
a principal role in adaptive mechanisms to high heat burden and dehydration as
its composition and volume remains relatively constant and hemoglobin function
remains normal. The erythrocytes of the camel are oval shaped and non-nucleated
which resist osmotic variation without rupturing; these cells can swell to twice
their initial volume following rehydration. Another unique feature of the
erythrocytes is their long life span when the camel is dehydrated. The life
span of the erythrocytes of hydrated camels is 90 to 120 days. When camels were
chronically dehydrated during summer (40oC mean during day; 20oC mean at night)
the life span of erythrocytes was extended to 150 days. Erythrocyte turnover is
water and energy expensive. Therefore extending the life span of erythrocytes reduces
energy and water expenditure
A fully hydrated camel
has a diurnal body temperature range of 36 to 38oC. However when dehydrated and
exposed to high environmental heat load body temperature may fluctuate by 6 to
7oC, from approximately 34 to 41o C. The increase in body temperature of camels
exposed to high heat load, especially following a 2o C reduction below the
normal minimum, is advantageous because it allows a considerable amount of heat
to be stored during the day and dissipated at night (by radiation) without the
expenditure of water. Furthermore, as body temperature increases the
temperature gradient between the camel and the external environment is reduced,
and again water use is reduced. The camel has a bi-phasic air flow pattern,
i.e. the inspiratory and expiratory flow rates through the nasal turbinate are
similar. The bi-phasic breathing pattern also reduces water use.
Conclusion
The camel is a unique
desert creature and it employees a number of adaptive strategies that allow it
to survive harsh and hostile conditions of its habitat. Camel, because of its
special physiology and adaptive mechanism, not only survive in hostile
conditions but also produce precious milk for its herder. Camel is a tool of
food security and livelihood for camel herders in difficult environments. Camel
can be used as a tool of food security in the climate change context and water
scarcity. It is the utmost need of time to conserve camel genetic resources
through utilization of its precious and unique products, especially its milk
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