There's a great phrase I like to say when someone asks if they boa is a BCC or BCI. "If you have to ask, it's a BCI".
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Without a doubt, BCI. Pure BCI? Who knows. Impossible to tell without knowing the parent's and their ancestry.
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The difference between the two are as clear as night and day once you have looked at a whole bunch of photos of each ssp. Color, size, saddle counts being the more obvious differentiation. But one thing than many people often overlook is the morphological "look" between constrictor and imperator. Head shape (as well as size) and body shape are very much different between them. BCI tend to have a more roundish body where as BCC have a rectangular shape to them.
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Fun stuff.