Image# M054 - Rhea Eggs
Rhea eggs can be 'candled' to see if they are fertile 7-10 days after being laid. This means that they are held over a strong light in a dark room. The light colour in the shell is the air sac. The chick in this egg has not yet 'internally pipped'. This means that its beak has not yet broken into the air sac, which happens as it struggles to breathe. Once the chick runs out of air, it breaks through the shell and hatches.