The document summarizes various adaptations that allow animals to survive in arid desert environments. It discusses physiological adaptations like water and fat storage, coloration, size and shape. It also describes behavioral adaptations such as aestivation, seasonal migration and activity patterns. Key animal examples mentioned include camels, kangaroo rats and fennec foxes. The adaptations allow desert animals to avoid dehydration and regulate water balance while enduring high temperatures and lack of water.

1. Arid Environments E3176 Erçin Öncel E3331 Vassilis Bitsikas E3175 Aslıhan Çoban School of Sciences Department of Biology Do Minho University Animal Physiology 14.01.2010

2. Water Balance in Animals Gain Oxidation water Water in food Drink water Loss Evaporation from skin Evaporation from lungs Water in faeces Water in urine

3. Water Balance in Animals Evaporation from skin For mammals, evaporative heat loss includes sweating. Evaporation from lungs Water loss through the respiratory tract averages. Exp panting. Water in feces Normal gastrointestinal loss of water in feces is generally quite small. Water in urine Urea is very toxic compound in the body which is converted from ammonia by some enyzme. It needs to take it away from body. Some water spends during this process couse of that, It easily soluble in water and has a moderately low toxicity Loss;

4. Water Balance in Animals Drink water Animals can gain water directly drinking water Water in food Animals can gain water due to foods especially, fruits and vegetables Oxidation water The water resulting from the oxidation of nutrients such as protein, carbonhydrates and fats. Gain;

5. Deserts A desert is a very dry place. It either receives an average annual rainfall of less than 250 mm or has more water that is lost than falls as rain. A desert can be freezing cold or burning hot. Most of a desert is made up of sand or snow, sand dunes or snowdrifts, and cacti or very small plants. It is a biome, one where there is little rainfall.

6. Types of Deserts We can separate the deserts according to rainfall and temperature

7. Deserts in the World

8. ESCAPE FROM THE DESERT ENVIRONMENT How important the exploitation of favourable micro-climates is within the desert ecosystem How desert organisms avoid the harshness of the desert climate

9. AESTIVATION SEOSANAL MIGRATION

10. AESTIVATION Estivatition, also known as ‘summer sleep’, is a state of animal dormancy somewhat similar to hibernation Estivatition: Sleep during hottest parts of each year( July and August )

11. GROUND SQUIRRELS GENUS: Citellus They sleep for about seven months a year in burrows when the air temperature gets above 98 degrees Fahrenheit

12. SPADEFOOT TOADS GENUS: Scaphiopus They spend most of the time during the dry season buried in the ground in estivation

13. AFRICAN BULLFROG Pyxicephalus adspersus It makes a dry, watertight cocoon for itself, which prevents the evaporation of body fluids; without a cocoon looses it loses Approximately half of the water that a frog

14. Seasonal Migration The periodic movement of a population from one region or climate to another in accordance with the yearly cycle of weather and temperature changes.

15. THE NAMAQUA SANDGROUSE Phainopepla nitens This species winters in the deserts of the South-Western United States and with the advent of hot summer conditions, moves to the more mesic environments surrounding the desert areas.

16. Physiological and behavioural adaptations

17. Tolerance of the Arid Environment Morphological Adaptations WATER STORAGE ECTOPIC STORAGE OF FAT ANIMAL COLOUR SHAPE AND SIZE

18. WATER STORAGE Both plants and animals employ water storage as a mechanism of defence against prolonged droughts in the desert. Henderson and Loveridge have examined the role of hypo-osmotic urine in the water economy of Chersina angulata.

19. Desert Tortoises They established that when these animals were exposed to starvation and desiccation,there was a progressive reduction in urine volume and concluded that ‘Bladder urine’ was potentially an important source of water for this species

20. Ectopic Storage Of Fat Fat storage in animals would be especially important to allow survival during prolonged periods of drought and shortages of food energy

21. Large desert- adapted mammals show a similar form of adaptation : Antelopes Camels Humbed do zebu cattle Fat-tailed sheep

22. Animal Colour Cryptic Coloration is particularly well developed in many desert animals. Lizards, snakes, grasshoppers and the precocious chicks of some ground-nesting birds.

23. The desert tenebrionid; Cryptoglossa verrucosa changes from a jet-black to light blue when the relative humidity decreases.

24. Shape and Size Body size and shape are most important considerations in evaluating the adaptation of desert animals.

25. Oryx This species,because of its large size, has a high thermal inertia and will be able to store a large amount of heat in its body tissues during the day without resorting to the evaporation of precious water for cooling purposes.

26. tough, dry, heavily keratinized skin shelled, amniotic egg Adaptations that unshackled reptiles from the aquatic environment. No more dependence on aquatic or very moist terrestrial environments.

27. Arthropod cuticle Lipid-like deposits provide waterproof properties and minimise water losses by reducing the cuticular transpiration

28. Specialized spiracle structure that minimises water loss

29. Behavioural thermoregulation

30. A ctivity of the antelope ground squirrel Ammospermophilus leucurus during a typical day in the Nevada desert Ammospermophilus is an evader but a degree of endurance is indicated too.

31. Adaptive heterothermy The ability of an endothermic animal to allow its body temperature to fluctuate in response to some form of environmental stress. Saving significant amounts of energy and water. Maximum fluctuation during 1 day: 6,2 ° C

32. Osmoregulation Period of dehydration: day 4 - 12

33. Negative f eedback control of the secretion of antidiuretic hormone, ADH

34. T wo types of nephron, distinguished by the length of their loops of Henle Most mammalian kidneys contain a mixture of the two types but some species have only one or the other

35. Cortical nephrons have short-reach loops that just penetrate the boundary between the inner and outer zones of the medulla. Juxtamedullary nephrons have long-reach loops that penetrate deep into the medulla. The longer the loop of Henle relative to the overall depth of the cortex, the higher is the osmolarity of the fluid in the bend. The kidney thereby retains as much water as possible, minimising loss of water during water shortage. Most loops of Henle in desert rodents are of the juxtamedullary type and could therefore be viewed as a desert adaptation

36. Uric acid is highly insoluble and easily precipitates from solution, allowing its removal in almost solid form. Excertion The key feature that seems to determine choice of nitrogenous waste is availability of water in the environment.

37. Tolerance to Dehydration Desert amphibians can tolerate 40-50% losses of body water A camel can lose 30% of its body water and retain it back in 10 minutes. For other large mammals a 12-14% weight loss is lethal. [capacious rumen (fore-stomach) protect them from osmotic stress] Store water

38. What is the physiological differences Between desert and arctic fox? Its legs, ears and muzzle are long to dissipate heat, and it has a high surface area The coat is often a cream color and fluffy, which deflects heat during the day and keeps them warm at night Its legs, ears and muzzle are short to dissipate heat its tail like a muffler when cold. The fox has a low surface area Its fur changes color with the seasons: in the winter it is white to blend in with snow, while in the summer months it changes to brown.

39. Adaptations of Desert Animals Dromedary Camel ( Camelus dromedarius ) A camel can last three months without water, a special adaptation for desert living. Camels store fat in the hump, not water. The fat can be metabolized for energy. Unlike most mammals, a healthy camel's body temperature fluctuates throughout the day from 34°C to 41.7°C (93°F-107°F.) This allows the camel to conserve water by not sweating as the environmental temperature rises. Camels have nostrils that can open and close, protecting the respiratory tract from blowing sand.

40. Adaptations of Desert Animals Kangaroo Rat ( Dipodomys deserti ) They have large hind feet that keep them from sinking into the sand. Kangaroo rats dig burrows to protect themselves from predators and heat. Kangaroo Rats are nocturnal (avoiding the heat during the day.) Large ears help dissipate heat. Kangaroo rats may obtain their water from the food they eat.

41. Adaptations of Desert Animals Fennec Fox ( Vulpes zerda ) Their large ears, which are usually 4 to 6 inches long, help dissipate excess body heat on hot days in the desert. Their burrowing and nocturnal lifestyle helps restrict water loss. Their thick fur helps insulate them from the cold desert nights. Their sandy coloration helps to reflect heat, and also provides excellent camouflage

42. Conclusions The key to the survival in hot, dry environments consists in avoiding climatic extremes as far as possible, by a combination of seeking refuge from the most adverse conditions, morphological adaptations, behaviour and specialized physiology. Whereas thermal reactions are primarily behavioural, adaptational responses to aridity are mostly physiological. Exploitation of desert habitats involves a vast complex of adaptive compromises between set of factors.

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