I am 30, the OP is 27 and the Mom doesn't see a 27 year old, she sees a child. Believe it or not I chose the word "child" carefully. The question is of course loaded. The question is, does the mother want to cut her adult offspring out of her life over a snake. There is nothing quite like the love a mother has for her child. So the plan is to use that. You want Mom to realize that no matter how much she hates the snakes, she loves her child more. Now in reality her child is 27 years old and is far from a child and that's why the ball is in Mom's court. She needs to know that she can no longer control her child and that now she has to choose to accept and support the OP's choices or damage the most important relationship in her life.
In the end the message that everyone needs to understand is that you can not change other people. You can change yourself, and you help someone through the process of change, but you can not force your will on another and expect anything good to come from it.
So Mom needs to change and adapt or suffer and child needs to change and adapt or suffer.
I like set theory so here it is. 3 outcomes
1. stratus_020202 keeps the snakes and mom doesn't accept that.
stratus_020202and mom
2. stratus_020202 gets rid of the snakes and mom is thrilled.
stratus_020202and mom
3. stratus_020202 keeps the snakes and mom accept that.
stratus_020202and mom
Keeping the snakes should be stratus_020202's choice, because its the only one that has the potential to make stratus_020202 happy. Mom then has to choice between outcome 1 or 3. Lets hope she chooses awkward acceptance over sad and angry. Its sounds like Mom is already coming around to a reluctant acceptances.