I am presuming your book is still not yet published. Publishing is synonymous to getting that copyright for protecting your book which is why it is highly important to publish it.

Protection can go a long way. But I've written something about the significance of getting a copyright. I hope this helps. :)

Copyright or not, your literary work belongs to you. No one gets anything without asking and nothing has ever been free in this literary world of ours. The author, artist and publisher must be sophisticated enough in their negotiations to provide for virtually all contingencies including but not limited to what happens to the copyright under certain circumstances.

Good luck!

Source: http://tr.im/uHhG