If you get a job and go to work and do whatever it is you do, and then get a paycheck... you have to pay the IRS money. In the US we have income tax and you are supposed to pay it on any and all income, regardless of where/how you get that income. There are a few things that are exempt, but I still believe you are supposed to report the income, and then explain why it is exempt.
So, yes, you should be reporting and paying income tax on any snake sales.