Penultimate makes an excellent point. Maybe you could bring the snek in once a month, on a schedule, and interested parties can set aside time to get some 1:1 interaction with the animal.
This is a great idea - my only suggestion would be to exchange "colors" for "gene-variant patterns and colors", since these are 9th graders (14 yr olds?)... they're old enough get the full explanation, I hope. ;)
I don't know if you cover Punnett Squares in your class, OP, but BPs would be a great way to do it, pics and all! Way more interesting than pea-plants with white and purple flowers, IMO. :| Memories, memories...