Clown fish and shrimp, variation in size and why, also why do clown fish wobble?

More or less all clown fish of both sexes are the same size.
Just the male normally is the one that gets eatern while defending and is replaced.
Quite often with commercial collectors, when you get a large one that is on its own you find a small one under 25 mill to put with the large one as they do not have a locked in sex yet and a pair will come from that.
The exact same thing with banded shrimp and other non lysmata shrimp.
The wobble is to show submition to avoid harm, just like a puppy pointing its tail and shaking.