With Animal Crossing: New Leaf, it's all in the little details. You can blow a dandelion, for example... or, you can watch a tarantula and a scorpion duke it out.
Amazingly, when you donate both a tarantula and a scorpion to your museum, this happens. Who wins? Since this is Animal Crossing, it's a tie. Maybe you don't find that surprising, but I kind of do, since both these creatures can mess you up in-game if you're not careful.
Still, it's cool to see how stuff acts in the museum. As I understand it, if you donate a piranha, it'll chase you and try to eat you. Of course!
And if you're curious... this is a real life tarantula versus scorpion. The tarantula totally wins.