I sell spiders, I've not got a license as I breed them, I used to breed and sell snakes without a license, but it's not really a business it's a byproduct of a hobby, or my pets and its small scale stuff
I'd guess if its a business you'd need the license, I'm expanding my breeding stock at the moment and am thinking of putting it through my company books and its something I've been pondering myself, it's more a welfare thing as far as I know, I've already got a 'dangerous wild animal license' and that's fairly onerous in proving everything's secure, mind I don't at present have anything that's on the schedule