No reason to apply the word tetrachromatic though, like the guy does in the video. All birds are tetrachromatic, it's part of their better-than-human visual ability. It's not related to chimerism.

I have seen those a few times in a chicken's egg! I often wondered what would happen if the egg was actually fertile, and guessed that the same egg would produce two separate individuals. Not true, then? It would always produce one individual with double DNA?

Which brings me to the next question. Mono-zygote twins have identical DNA, right? If so, why the narrator in this video says that the halfsiders have two separate sets of DNA? Shouldn't it be one and the same even though it comes from two different individuals?

Usually a double-yolked egg would produce two different individuals, although it's rare for them to actually hatch and survive. Chimerism is a very rare anomaly.



With mono-zygote (identical) twins, one original individual split into two different individuals with the same DNA. A chimera is the opposite of this - two non-identical twins merged into one individual. The original individuals had different DNA, so the merged individual will have different DNA in different parts of the body depending on which twin that body part came from.

Thank you for explaining this. I thought that two yolks in the same shell would be like identical twins.
I also didn't know that mono-zygote twins are one original individual split into two... Fascinating stuff, my mother and my auntie are identical twins and the idea that they are "split" gives me goosebumps, because they really were two pieces of the same individual, never happy when apart from each other.

I know someone who bred her budgies and got a half sider ..........

Wow, that's very rare! Do you have any pictures?

Identical twins would be two birds in the same egg with just one yolk. They say identical twins never hatch successfully, I'm guessing because there's only enough nutrients in the egg for one baby not two. But double-yolk eggs are usually bigger than normal eggs, and sometimes there's enough of everything for both non-identical twin babies to hatch.

So its like a twin to twin thing?

Sorry, it was some one I knew awhile back.......... no pics.
It was half violet and blue.

Wow this has been really interesting..
thanks ladies Ive learnt a lot...