Reading Handa's surprise to my three year old, he became interested in why the giraffe's tongue is black. He also asked what colour tongue do the other animals have.
Giraffe:
Antelope:
Okapi:
(ok so there isn't an okapi in Handa's surprise)
Does anyone know if there is any selection pressure that has caused a number of African mammals to have black tongues? (And how I'd explain it to a three year old!)