Another question for Dr. Fry...

[Simon Sansom]

Okay, with all of this talk about venomous colubrids lately, I'd like to ask -
What, if any, benefit does the snake derive from having these toxins? For example, is the venom of an Asian rat snake actually of any use in capturing prey? Everything evolves for a purpose, correct? If these toxins are even only present in relatively small amounts, why even have them at all?

... Or am I missing a key point here?

Thanks,

Simon