Giraffe - The Facts
The giraffe's patches and body heat control
The giraffe's patches are first and foremost for camouflage. But underneath eacth patch is a really sophisticated blood system. Around each patch there is quite a 'large' blood vessel and that blood vessel gives off smaller branches into the middle of the patch (see below).
What a giraffe is able to do is to send blood through these little branches into the middle of the patch and heat is given off through that system. Each one acts as a thermal window to release body heat.
The figure on the left below shows the giraffe’s patches and the other on the right shows the intensity of heat radiation where these patches are concentrated on the giraffe’s body.
The larger the neck, the greater the surface area for giving off this heat and the overall long thin body increases surface area dramatically. Evolution of a body shape that stays cool under the African sun could well be one of the reasons for the giraffe's extraordinary neck.