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

1. Physiological

2. Behavioural

Low levels of sweat

Low volume urine

Copes with up to 30% water loss – most animals die around 10%

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

Special red blood cells can swell up without bursting and shrink without camel dying

Camel can tolerate body temperature changes of more than three times of changes that would kill us

Fat in hump releases water when broken down

Special mechanism keeps brain cool

Camels – Can survive in desert for up to 14 days with no water

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

before returning back into the body.

Water RegulationWater Regulation• The kidneys regulate water, but this is The kidneys regulate water, but this is

controlled by the brain.controlled by the brain.

• The brain produces The brain produces ANTI-DIURETIC ANTI-DIURETIC HORMONEHORMONE (A.D.H.) (A.D.H.) which controls the which controls the volume of water reabsorbed by the kidney volume of water reabsorbed by the kidney nephrons.nephrons.

• Different volumes of ADH are produced to Different volumes of ADH are produced to suit the varying water conditions of the suit the varying water conditions of the body, ensuring water balance is maintained.body, ensuring water balance is maintained.

Bowman’s Capsule

No sweat glands

Long loop of henle and high ADH level which give very efficient water reabsorption

Low volume of urine produced

High water absorption in large intestine

Very dry faeces

Dry nasal passagesWater in exhaled air condenses here Don’t go looking for

water to drink (waste of energy)

Eat fatty seeds ( get lots of water when metabolised)

Spend day inactive in a humid burrow ( cooler so reduces water lost through breathing)

Forage at night ( cooler so no need to sweat)

Kangaroo Rat

Heat exchange in nasal passages

Air here is cooler so less water held in it.