I want a hermit crab?

I have a ten gallon tank, it currently has guppies in it, but they keep multiplying, and its getting too crowded, im going to get rid of all the females, and let the males eventually die off. It is also hard to clean, and guppies aren't my favorite fish. (we got them from a friend because he was moving and he couldnt take them) and I dont want them. So, after they eventually die off, I want to put hermit crabs in it. My mom doesnt like creepy crawlers, that have a bunch of legs, weird eyes, etc. so she said no. I love hermit crabs, and i actually find them kind of cute:] any ideas on convincing my mom?