You get a plate or take-out container and make your selection either blindly or informed, by asking nicely and trying to remember if there's a chapter on animal parts in your phrasebook.
The animal carried by a passenger, together with its container and food, is not included in the free baggage allowance.
旅客携带的小动物及其容器和食物,不包括在其免费行李额之内。
3
But the rules say nothing about the size of the animal or the container, and as you can see from this picture, some people are quick to exploit that fact in order to avoid a fine.