Ol’ Blue Eyes

Editor@gomag.co.za

were a little grossed out by the thought of them eating a family member…

Wildlife expert

LD VAN ESSEN says:

The behaviour exhibited here is called osteophagy and it’s a way for the animals to supplement their calcium and phosphate intake. It’s common among herbivores, especially giraffes. The giraffes don’t chew the bone and they don’t swallow it either – they gnaw on it and ingest the scrapings. To us humans, the thought of giraffes gnawing on a relative’s bones might be offputting, but they see the bones as a resource and have no emotional attachment.

Even though bone gnawing benefits the herbivores, it comes at a price: tooth decay and broken teeth.

LUCY STEPHENS from Edenvale writes: My husband Andrew and I came across a herd of zebras on the Albasini Road near the Kruger’s Phabeni gate. Quite a few of the adult animals, as well as the foals, had blue eyes. One or two had one brown eye and one blue eye. This did not seem to hinder the zebras in any way. Is this genetic or do the animals have a sort of deficiency?

Wildlife expert LD VAN ESSEN says: Zebras and other mammals with blue eyes have less melanin pigment in the eye, specifically the stroma layer of cells in the iris. When the eye has less pigment, it reflects light differently and appears blue. In other words, the colour is caused by the structure of the eye, not by blue pigment.

When an animals’ eyes are different colours, it is known as heterochromia. The condition can be hereditary or caused by an injury, but it usually has no effect on the animal’s ability to see. Since many of the zebras in this herd have this condition, I would say it’s genetic.