Desert Mammals Land animals lose water This problem is greater for animals living in hot, dry areas such as deserts as there is little water to replace the lost water Such animals are adapted in a number of ways to survive in such conditions. These adaptations are either Physiological Behavioural

Camels – Can survive in desert for up to 14 days with no water Special mechanism keeps brain cool Fat in hump releases water when broken down Camel can tolerate body temperature changes of more than three times of changes that would kill us Low levels of sweat Copes with up to 30% water loss – most animals die around 10% Low volume urine Special red blood cells can swell up without bursting and shrink without camel dying Can drink up to 30% of its body weight when it finds water – 200L in 3 minutes Can store large amount of water in gut

Storing heat A dehydrated camel will increase its body temperature in an effort to prevent water loss through evaporation. The camel can tolerate the high temperatures, and consequently it stores the heat during the day which causes drastic body temperature fluctuations. Instead of letting the heat evaporate during the day and thus using water, the camel stores the heat until when the cool night allows for the stored heat in the camel to be released by conduction and diffusion

Brain Cooling Blood runs around the nasal passages and cools down Brain cooling is an essential thermoregulatory adaptation in heat stressed animals. The gazelle's body temperature greatly increases when running at high speeds for an extended period of time, however this built up heat stress within the body does not affect  the most sensitive part, the brain, due to brain cooling. Blood runs around the nasal passages and cools down before returning back into the body.

Water Regulation The kidneys regulate water, but this is controlled by the brain. The brain produces ANTI-DIURETIC HORMONE (A.D.H.) which controls the volume of water reabsorbed by the kidney nephrons. Different volumes of ADH are produced to suit the varying water conditions of the body, ensuring water balance is maintained.

Bowman’s Capsule

Kangaroo Rat Forage at night ( cooler so no need to sweat) Spend day inactive in a humid burrow ( cooler so reduces water lost through breathing) Forage at night ( cooler so no need to sweat) Long loop of henle and high ADH level which give very efficient water reabsorption No sweat glands Low volume of urine produced Dry nasal passages Water in exhaled air condenses here Don’t go looking for water to drink (waste of energy) Heat exchange in nasal passages High water absorption in large intestine Air here is cooler so less water held in it. Eat fatty seeds ( get lots of water when metabolised) Very dry faeces Kangaroo Rat