camels

[dolphin99]

Why would a camel not be expected to have a 'heat exchange system' in its legs.

[Octavius]

The localisation of body fat within the camel�s hump aids in the dissipation of body heat, as does the distribution of the hair which is short on the lateral and ventral aspects of the body but long on the hump and over the dorsal surface. This has the effect of reducing absorption of radiant heat on the dorsal surface of the body whilst allowing the dissipation of body heat on all other aspects.

When water is available the camel utilises sweating rather than panting for evaporative cooling. This method is highly effective in cooling the animal because areas where sweat production occurs has limited subcutaneous fat and the coat in these areas is relatively short, allowing sweat to evaporate directly from the skin surface.

Even when dehydrated the camel is able to maintain plasma volume and thereby continue blood circulation to the skin for heat exchange. This ability to maintain plasma volume is achieved through the modification of plasma proteins and the balance of osmotic pressure through the retention of sodium ions.

Evaporative cooling is also aided by specialised blood vessels within the camel�s legs which allow counter current heat exchange during normal blood circulation. The long legs of the camel allows better ventilation when standing but also reduce the amount reflected heat absorbed from the ground surface during the day. The large keratinised pad on the chest has a similar effect as it reduces surface contact with the ground when the animal is recumbent.