Giraffe tongue coloration

[Mascarell]

I've read in many books the following theories.

1.- The more epidermis present on the tongue, follows more capillar irrigation needs, and so that blue color. All to prevent the spines on acacia trees. (resumed)

2.- Protection from the sun, as they spend a lot of time browsing. (resumed)

3.- Dermal layers of dead tissue to make the lips and tongue stronguer to support the spines on acacia trees. (resumed)

Is there any true? Do you have any answer or theory to that?

I've seen that Okapi (Okapi johnstonii) do have the same coloration in the tongue, so... probably the spines of the acacia will not be the strongest theory.

Thanks to all!!
Alex Mascarell